Synnefo Administrator’s Guide

This is the complete Synnefo Administrator’s Guide.

General Synnefo Architecture

The following figure shows a detailed view of the whole Synnefo architecture and how it interacts with multiple Ganeti clusters. We hope that after reading the Administrator’s Guide you will be able to understand every component and all the interactions between them.


Required system users and groups (synnefo, archipelago)

Since v0.16, Synnefo requires an Archipelago installation for the Pithos backend. Archipelago on the other hand, supports both NFS and RADOS as storage backends. This leads us to various components that have specific access rights.

Synnefo ships its own configuration files under /etc/synnefo. In order those files not to be compromised, they are owned by root:synnefo with group read access (mode 640). Since Gunicorn, which serves Synnefo by default, needs read access to the configuration files and we don’t want it to run as root, it must run with group synnefo.


If you want to add your own configuration file, do not forget to declare the appropriate encoding by adding the line ## -*- coding: utf-8 -*- at the beggining of the file.

Cyclades and Pithos talk to Archipelago over some named pipes under /dev/shm/posixfd. This directory is created by Archipelago, owned by the user/group that Archipelago runs as, and at the same time it must be accessible by Gunicorn. Therefore we let Gunicorn run as synnefo user and Archipelago as archipelago:synnefo (by default it rus as archipelago:archipelago). Beware that the synnefo user and group is created by snf-common package.

Archipelago must have a storage backend to physically store blocks, maps and locks. This can be either an NFS or a RADOS cluster.

NFS backing store

In case of NFS, Archipelago must have permissions to write on the exported dirs. We choose to have /srv/archip exported with blocks, maps, and locks subdirectories. They are owned by archipelago:synnefo and have g+ws access permissions. So Archipelago will be able to read/write in these directories. We could have the whole NFS isolated from Synnefo (owned by archipelago:archipelago with 640 access permissions) but we choose not to (e.g. some future extension could require access to the backing store directly from Synnefo).

Due to NFS restrictions, all Archipelago nodes must have common uid for the archipelago user and common gid for the synnefo group. So before any Synnefo installation, we create them here in advance. We assume that ids 200 and 300 are available across all nodes.

# addgroup --system --gid 200 synnefo
# adduser --system --uid 200 --gid 200 --no-create-home \
    --gecos Synnefo synnefo

# addgroup --system --gid 300 archipelago
# adduser --system --uid 300 --gid 300 --no-create-home \
    --gecos Archipelago archipelago

Normally the snf-common and archipelago packages are responsible for creating the required system users and groups.

Identity Service (Astakos)

Authentication methods

Astakos supports multiple authentication methods:

  • local username/password
  • LDAP / Active Directory
  • SAML 2.0 (Shibboleth) federated logins
  • Google
  • Twitter
  • LinkedIn

Shibboleth Authentication

Astakos can delegate user authentication to a Shibboleth federation.

To setup shibboleth, install package:

apt-get install libapache2-mod-shib2

Change appropriately the configuration files in /etc/shibboleth.

Add in /etc/apache2/sites-available/synnefo-ssl:

ShibConfig /etc/shibboleth/shibboleth2.xml
Alias      /shibboleth-sp /usr/share/shibboleth

<Location /ui/login/shibboleth>
  AuthType shibboleth
  ShibRequireSession On
  ShibUseHeaders On
  require valid-user

and before the line containing:

ProxyPass        / http://localhost:8080/ retry=0


ProxyPass /Shibboleth.sso !

Then, enable the shibboleth module:

a2enmod shib2

After passing through the apache module, the following tokens should be available at the destination:

eppn # eduPersonPrincipalName

Astakos keeps a map of shibboleth users using the value of the REMOTE_USER header, passed by the mod_shib2 module. This happens in order to be able to identify the astakos account the shibboleth user is associated to, every time the user logs in from an affiliate shibboleth IdP.

The shibboleth attribute which gets mapped to the REMOTE_USER header can be changed in /etc/shibboleth/shibboleth2.xml configuration file.

<!-- The ApplicationDefaults element is where most of Shibboleth's SAML bits are defined. -->
    <ApplicationDefaults entityID=""
     REMOTE_USER="eppn persistent-id targeted-id">


Changing mod_shib2 REMOTE_USER to map to different shibboleth attributes will probably invalidate any existing shibboleth enabled users in astakos database. Those users won’t be able to login to their existing accounts.

Finally, add ‘shibboleth’ in ASTAKOS_IM_MODULES list. The variable resides inside the file /etc/synnefo/20-snf-astakos-app-settings.conf

Twitter Authentication

To enable twitter authentication while signed in under a Twitter account, visit

Click Create an application.

Fill the necessary information and for callback URL give:

Edit /etc/synnefo/20-snf-astakos-app-settings.conf and set the corresponding variables ASTAKOS_TWITTER_TOKEN and ASTAKOS_TWITTER_SECRET to reflect your newly created pair. Finally, add ‘twitter’ in ASTAKOS_IM_MODULES list.

Google Authentication

To enable google authentication while signed in under a Google account, visit

Under API Access select Create another client ID, select Web application, expand more options in Your site or hostname section and in Authorized Redirect URIs add:

Edit /etc/synnefo/20-snf-astakos-app-settings.conf and set the corresponding variables ASTAKOS_GOOGLE_CLIENT_ID and ASTAKOS_GOOGLE_SECRET to reflect your newly created pair. Finally, add ‘google’ in ASTAKOS_IM_MODULES list.

Working with Astakos

User registration

When a new user signs up, he/she is not directly marked as active. You can see his/her state by running (on the machine that runs the Astakos app):

$ snf-manage user-list

More detailed user status is provided in the status field of the user-show command:

$ snf-manage user-show <user-id>

id                  : 6
uuid                : 78661411-5eed-412f-a9ea-2de24f542c2e
status              : Accepted/Active (accepted policy: manual)
email               :

Based on the astakos-app configuration, there are several ways for a user to get verified and activated in order to be able to login. We discuss the user verification and activation flow in the following section.

User activation flow

A user can register for an account using the astakos signup form. Once the form is submited successfully a user entry is created in astakos database. That entry is passed through the astakos activation backend which handles whether the user should be automatically verified and activated.

Email verification

The verification process takes place in order to ensure that the user owns the email provided during the signup process. By default, after each successful signup astakos notifies user with an verification url via email.

At this stage:

  • subsequent registrations invalidate and delete the previous registrations of the same email address.
  • in case user misses the initial notification, additional emails can be send either via the url which is prompted to the user if he tries to login, or by the administrator using the snf-manage user-activation-send <userid> command.
  • administrator may also enforce a user to get verified using the snf-manage user-modify --verify <userid> command.
Account activation

Once the user gets verified, it is time for Astakos to decide whether or not to proceed through user activation process. If ASTAKOS_MODERATION_ENABLED setting is set to False (default value) user gets activated automatically.

In case the moderation is enabled Astakos may still automatically activate the user in the following cases:

  • User email matches any of the regular expressions defined in ASTAKOS_RE_USER_EMAIL_PATTERNS (defaults to [])
  • User used a signup method (e.g. shibboleth) for which automatic activation is enabled (see authentication methods policies).

If all of the above fail to trigger automatic activation, an email is sent to the persons listed in ACCOUNT_NOTIFICATIONS_RECIPIENTS setting, notifying that there is a new user pending for moderation and that it’s up to the administrator to decide if the user should be activated. The UI also shows a corresponding ‘pending moderation’ message to the user. The administrator can activate a user using the snf-manage user-modify command:

# command to activate a pending user
$ snf-manage user-modify --accept <userid>

# command to reject a pending user
$ snf-manage user-modify --reject --reject-reason="spammer" <userid>

Once the activation process finishes, a greeting message is sent to the user email address and a notification for the activation to the persons listed in ACCOUNT_NOTIFICATIONS_RECIPIENTS setting. Once activated the user is able to login and access the Synnefo services.

Additional authentication methods

Astakos supports third party logins from external identity providers. This can be usefull since it allows users to use their existing credentials to login to astakos service.

Currently astakos supports the following identity providers:

To enable any of the above modules (by default only local accounts are allowed) you have to install oauth2 package. To do so run:

apt-get install python-oauth2

Then retrieve and set the required provider settings and append the module name in ASTAKOS_IM_MODULES.

# settings from

# let users signup and login using their google account
ASTAKOS_IM_MODULES = ['local', 'google']
Authentication method policies

Astakos allows you to override the default policies for each enabled provider separately by adding the approriate settings in your .conf files in the following format:


Available policies are:

  • CREATE Users can signup using that provider (default: True)
  • REMOVE/ADD Users can remove/add login method from their profile (default: True)
  • AUTOMODERATE Automatically activate users that signup using that provider (default: False)
  • LOGIN Whether or not users can use the provider to login (default: True).

e.g. to enable automatic activation for your academic users, while keeping locally signed up users under moderation you can apply the following settings.


User login

During the logging procedure, the user is authenticated by the respective identity provider.

If ASTAKOS_RECAPTCHA_ENABLED is set and the user fails several times (ASTAKOS_RATELIMIT_RETRIES_ALLOWED setting) to provide the correct credentials for a local account, he/she is then prompted to solve a captcha challenge.

Upon success, the system renews the token (if it has expired), logins the user and sets the cookie, before redirecting the user to the next parameter value.

Projects and quota

Synnefo supports granting resources and controling their quota through the mechanism of projects. A project is considered as a pool of finite resources. Every actual resources allocated by a user (e.g. a Cyclades VM or a Pithos container) is also assigned to a project where the user is a member to. For each resource a project specifies the maximum amount that can be assigned to it and the maximum amount that a single member can assign to it.

Default quota

Upon user creation, a special purpose user-specific project is automatically created in order to hold the quota provided by the system. These system projects are identified with the same UUID as the user.

To inspect the quota that future users will receive by default through their base projects, check column system_default in:

# snf-manage resource-list

You can modify the default system quota limit for all future users with:

# snf-manage resource-modify <resource_name> --system-default <value>

You can also control the default quota a new project offers to its members if a limit is not specified in the project application (project default). In particular, if a resource is not meant to be visible to the end user, then it’s best to set its project default to infinite.

# snf-manage resource-modify cyclades.total_ram --project-default inf
Grant extra quota through projects

A user can apply for a new project through the web interface or the API. Once it is approved by the administrators, the applicant can join the project and let other users in too.

A project member can make use of the quota granted by the project by specifying this particular project when creating a new quotable entity.

Note that quota are not accumulative: in order to allocate a 100GB disk, one must be in a project that grants at least 100GB; it is not possible to add up quota from different projects. Note also that if allocating an entity requires multiple resources (e.g. cpu and ram for a Cyclades VM) these must be all assigned to a single project.

Reclaiming resources

When a project is deactivated or a user is removed from a project, the quota that have been granted to the user are revoked. If the user still owns resources assigned to the project, the user quota appear overlimit on that project. The services are responsible to inspect the overquota state of users and reclaim their resources. For instance, cyclades provides the management command enforce-resources-cyclades to reclaim VMs, volumes, and floating IPs.

When a user is deactivated, their system project, owned projects and project memberships are suspended. Subsequently, the user’s resources can be reclaimed as explained above.

Control projects

To list pending project applications in astakos:

# snf-manage project-list --pending

Note the last column, the application id. To approve it:

# <app id> from the last column of project-list
# snf-manage project-control --approve <app id>

To deny an application:

# snf-manage project-control --deny <app id>

Before taking an action, on can inspect project status, settings and quota limits with:

# snf-manage project-show <project-uuid>

For an initialized project, option --quota also reports the resource usage.

Users designated as project admins can approve or deny an application through the web interface. In 20-snf-astakos-app-settings.conf set:

# UUIDs of users that can approve or deny project applications from the web.
Set quota limits

One can change the quota limits of an initialized project with:

# snf-manage project-modify <project-uuid> --limit <resource_name> <member_limit> <project_limit>

One can set system quota for all accepted users (that is, set limits for system projects), with possible exceptions, with:

# snf-manage project-modify --all-system-projects --exclude <uuid1>,<uuid2> --limit ...

Quota for a given resource are reported for all projects that the user is member in with:

# snf-manage user-show <user-uuid> --quota

With option --projects, owned projects and memberships are also reported.

Astakos advanced operations

Adding “Terms of Use”

Astakos supports versioned terms-of-use. First of all you need to create an html file that will contain your terms. For example, create the file /usr/share/synnefo/sample-terms.html, which contains the following:

<h1>My cloud service terms</h1>

These are the example terms for my cloud service

Then, add those terms-of-use with the snf-manage command:

$ snf-manage term-add /usr/share/synnefo/sample-terms.html

Your terms have been successfully added and you will see the corresponding link appearing in the Astakos web pages’ footer.

During the account registration, if there are approval terms, the user is presented with an “I agree with the Terms” checkbox that needs to get checked in order to proceed.

In case there are new approval terms that the user has not signed yet, the signed_terms_required view decorator redirects to the approval_terms view, so the user will be presented with the new terms the next time he/she logins.

Enabling reCAPTCHA

Astakos supports the reCAPTCHA feature. If enabled, it protects the Astakos forms from bots. To enable the feature, go to and create your own reCAPTCHA key pair. Then edit /etc/synnefo/20-snf-astakos-app-settings.conf and set the corresponding variables to reflect your newly created key pair. Finally, set the ASTAKOS_RECAPTCHA_ENABLED variable to True:

ASTAKOS_RECAPTCHA_PUBLIC_KEY = 'example_recaptcha_public_key!@#$%^&*('
ASTAKOS_RECAPTCHA_PRIVATE_KEY = 'example_recaptcha_private_key!@#$%^&*('


Restart the service on the Astakos node(s) and you are ready:

# /etc/init.d/gunicorn restart

Checkout your new Sign up page. If you see the reCAPTCHA box, you have setup everything correctly.

Astakos internals


Alice requests a specific resource from a cloud service e.g.: Pithos. In the request she supplies the X-Auth-Token to identify whether she is eligible to perform the specific task. The service contacts Astakos through its /account/v1.0/authenticate api call providing the specific X-Auth-Token. Astakos checkes whether the token belongs to an active user and it has not expired and returns a dictionary containing user related information. Finally the service uses the uniq field included in the dictionary as the account string to identify the user accessible resources.

Django Auth methods and Backends

Astakos incorporates Django user authentication system and extends its User model.

Since username field of django User model has a limitation of 30 characters, AstakosUser is uniquely identified by the email instead. Therefore, is served to authenticate a user using email if the first argument is actually an email, otherwise tries the username.

A new AstakosUser instance is assigned with a uui as username and also with a auth_token used by the cloud services to authenticate the user. is also specified in order to authenticate the user using the email and the token fields.

Logged on users can perform a number of actions:

  • access and edit their profile via: /im/profile.
  • change their password via: /im/password
  • send feedback for grnet services via: /im/send_feedback
  • logout (and delete cookie) via: /im/logout

Internal Astakos requests are handled using cookie-based Django user sessions.

External systems should forward to the /login URI. The server, depending on its configuration will redirect to the appropriate login page. When done with logging in, the service’s login URI should redirect to the URI provided with next, adding user and token parameters, which contain the email and token fields respectively.

The login URI accepts the following parameters:

Request Parameter Name Value
next The URI to redirect to when the process is finished
renew Force token renewal (no value parameter)
force Force logout current user (no value parameter)

External systems inside the ASTAKOS_COOKIE_DOMAIN scope can acquire the user information by the cookie identified by ASTAKOS_COOKIE_NAME setting (set during the login procedure).

Finally, backend systems having acquired a token can use the ‘authenticate-api-label’ API call from a private network or through HTTPS.

File/Object Storage Service (Pithos+)

Pithos+ is the Synnefo component that implements a storage service and exposes the associated OpenStack REST APIs with custom extensions.

Pithos+ advanced operations

Enable separate domain for serving user content

Since Synnefo v0.15, there is a possibility to serve untrusted user content in an isolated domain.

Enabling this feature consists of the following steps:

  1. Declare new domain in apache server

    In order to enable the apache server to serve several domains it is required to setup several virtual hosts. Therefore, for adding the new domain e.g. “”, append the following in /etc/apache2/sites-available/synnefo-ssl:

    <VirtualHost _default_:443>
        Alias /static "/usr/share/synnefo/static"
        #  SetEnv no-gzip
        #  SetEnv dont-vary
       AllowEncodedSlashes On
       RequestHeader set X-Forwarded-Protocol "https"
    <Proxy * >
        Order allow,deny
        Allow from all
        SetEnv                proxy-sendchunked
        SSLProxyEngine        off
        ProxyErrorOverride    off
        ProxyPass        /static !
        ProxyPass        / http://localhost:8080/ retry=0
        ProxyPassReverse / http://localhost:8080/
        RewriteEngine On
        RewriteCond %{THE_REQUEST} ^.*(\\r|\\n|%0A|%0D).* [NC]
        RewriteRule ^(.*)$ - [F,L]
        SSLEngine on
        SSLCertificateFile    /etc/ssl/certs/ssl-cert-snakeoil.pem
        SSLCertificateKeyFile /etc/ssl/private/ssl-cert-snakeoil.key


    Consider also to purchase and install a certificate for the new domain.

    Finally, restart the apache server:

    pithos-host$ /etc/init.d/apache2 restart
  2. Register Pithos+ as an OAuth2 client in Astakos

    Starting from Synnefo version 0.15, in order to view the content of a protected resource, Pithos+ (on behalf of the user) has to be granted authorization for the specific resource by Astakos.

    During the authorization grant procedure, Pithos+ has to authenticate itself with Astakos since the latter has to prevent serving requests by unknown/unauthorized clients.

    Therefore, in the installation guide you were guided to register Pithos+ as an OAuth2 client in Astakos.


    You can see the registered clients by running:: astakos-host$ snf-manage oauth2-client-list -o identifier,redirect_urls,is_trusted

    However, requests originated from the new domain will be rejected since Astakos is ignorant about the new domain.

    Therefore, you need to register a new client pointing to the unsafe domain. To do so, use the following command:

    astakos-host$ snf-manage oauth2-client-add pithos-unsafe-domain --secret=<secret> --is-trusted --url


    You can also unregister the client pointing to the safe domain, since it will no longer be useful. To do so, run the following:

    astakos-host$ snf-manage oauth2-client-remove pithos-view
  3. Update Pithos+ configuration

    Respectively, the PITHOS_OAUTH2_CLIENT_CREDENTIALS setting should be updated to contain the credentials of the client registered in the previous step.

    Furthermore, you need to restrict all the requests for user content to be served exclusively by the unsafe domain.

    To enable this, set the PITHOS_UNSAFE_DOMAIN setting to the value of the new domain e.g. “”

    Finally, restart the gunicorn server:

    pithos-host$ /etc/init.d/gunicorn restart

Pithos storage backend

Starting from Synnefo version 0.16, we introduce Archipelago as the new storage backend. Archipelago will act as a storage abstraction layer between Pithos and NFS, RADOS or any other storage backend driver that Archipelago supports. For more information about backend drivers please check Archipelago documentation.

Since this version care must be taken when restarting Archipelago on a Pithos worker node. Pithos acts as an Archipelago peer and must be stopped first before trying to restart Archipelago for any reason.

If you need to restart Archipelago on a running Pithos worker follow the procedure below:

pithos-host$ /etc/init.d/gunicorn stop
pithos-host$ /etc/init.d/archipelago restart
pithos-host$ /etc/init.d/gunicorn start

Compute/Network/Image Service (Cyclades)


Cyclades is the Synnefo component that implements Compute, Network and Image services and exposes the associated OpenStack REST APIs. By running Cyclades you can provide a cloud that can handle thousands of virtual servers and networks.

Cyclades does not include any virtualization software and knows nothing about the low-level VM management operations, e.g. the handling of VM creation or migrations among physical nodes. Instead, Cyclades is the component that handles multiple Ganeti backends and exposes the REST APIs. The administrator can expand the infrastructure dynamically either by adding more Ganeti nodes or by adding new Ganeti clusters. Cyclades issue VM control commands to Ganeti via Ganeti’s remote API and receive asynchronous notifications from Ganeti backends whenever the state of a VM changes, due to Synnefo- or administrator-initiated commands.

Cyclades is the action orchestrator and the API layer on top of multiple Ganeti clusters. By this decoupled design, Ganeti cluster are self-contained and the administrator has complete control on them without Cyclades knowing about it. For example a VM migration to a different physical node is transparent to Cyclades.

Working with Cyclades

Flavors and Volume Types

When creating a VM, the user must specify the flavor of the virtual server. Flavors are the virtual hardware templates, and provide a description about the number of CPUs, the amount of RAM, and the size of the disk of the VM. Besides the size of the disk, Cyclades flavors describe the storage backend that will be used for the virtual server.

Flavors are created by the administrator and the user can select one of the available flavors. After VM creation, the user can resize his VM, by adding/removing CPU and RAM.

Cyclades support different storage backends that are described by the volume type of the flavor. Each volume type contains a disk template attribute which is mapped to Ganeti’s instance disk template. Currently the available disk templates are the following:

  • file: regulars file
  • sharedfile: regular files on a shared directory, e.g. NFS
  • plain: logical volumes
  • drbd: drbd on top of lvm volumes
  • rbd: rbd volumes residing inside a RADOS cluster
  • ext: disks provided by an external shared storage.
    • ext_archipelago: External shared storage provided by Archipelago.

Volume types are created by the administrator using the snf-manage volume-type-create command and providing the disk template and a human-friendly name:

$ snf-manage volume-type-create --disk-template=drbd --name=DRBD

Flavors are created by the administrator using snf-manage flavor-create command. The command takes as argument number of CPUs, amount of RAM, the size of the disks and the volume type IDs and creates the flavors that belong to the cartesian product of the specified arguments. For example, the following command will create two flavors of 40G disk size of volume type with ID 1, 4G RAM and 2 or 4 CPUs.

$ snf-manage flavor-create 2,4 4096 40 1

To see the available flavors, run snf-manage flavor-list command. The administrator can delete a flavor by using flavor-modify command:

$ snf-manage flavor-modify --deleted=True <flavor_id>

Finally, the administrator can set if new servers can be created from a flavor or not, by setting the allow_create attribute:

$ snf-manage flavor-modify --allow-create=False <flavor_id>

Flavors that are marked with allow_create=False cannot be used by users to create new servers. However, they can still be used to resize existing VMs.


When creating a VM the user must also specify the image of the virtual server. Images are the static templates from which VM instances are initiated. Cyclades uses Pithos to store system and user-provided images, taking advantage of all Pithos features, like deduplication and syncing protocol. An image is a file stored to Pithos with additional metadata that are describing the image, e.g. the OS family or the root partition. To create a new image, the administrator or the user has to upload it a file to Pithos, and then register it as an Image with Cyclades. Then the user can use this image to spawn new VMs from it.

Images can be private, public or shared between users, exactly like Pithos files. Since user-provided public images can be untrusted, the administrator can denote which users are trusted by adding them to the UI_SYSTEM_IMAGES_OWNERS setting in the /etc/synnefo/20-snf-cyclades-app-ui.conf file. Images of those users are properly displayed in the UI.

When creating a new VM, Cyclades pass the location of the image and it’s metadata to Ganeti. After Ganeti creates the instance’s disk, snf-image will copy the image to the new disk and perform the image customization phase. During the phase, snf-image sends notifications to Cyclades about the progress of the image deployment and customization. Customization includes resizing the root file system, file injection (e.g. SSH keys) and setting a custom hostname. For better understanding of snf-image read the corresponding documentation.

For passing sensitive data about the image to Ganeti, like the VMs password, Cyclades keeps all sensitive data in memory caches (memcache) and never allows them to hit the disk. The data are exposed to snf-image via an one-time URL that is exposed from the vmapi application. So, instead of passing sensitive data to snf-image via Ganeti, Cyclades pass an one-time configuration URL that contains a random UUID. After snf-image gets the sensitive data, the URL is invalidated so no one else can access them.

The administrator can register images, exactly like users, using a system user (a user that is defined in the UI_SYSTEM_IMAGES_OWNERS setting). For example, the following command will register the pithos://u53r-un1qu3-1d/images/debian_base-6.0-7-x86_64.diskdump as an image to Cyclades:

$ kamaki image register --name="Debian Base" \
       --location=pithos://u53r-un1qu3-1d/images/debian_base-6.0-7-x86_64.diskdump \
       --public \
       --disk-format=diskdump \
       --property OSFAMILY=linux --property ROOT_PARTITION=1 \
       --property description="Debian Squeeze Base System" \
       --property size=451 --property kernel=2.6.32 --property GUI="No GUI" \
       --property sortorder=1 --property USERS=root --property OS=debian

Deletion of an image is done via kamaki image unregister command, which will delete the Cyclades Images but will leave the Pithos file as is (unregister).

Apart from using kamaki to see and handle the available images, the administrator can use snf-manage image-list and snf-manage image-show commands to list and inspect the available public images. Also, the –user option can be used the see the images of a specific user.

Custom image listing sections

Since Synnefo 0.16.2, the installation wizard supports custom image listing sections. Images with the LISTING_SECTION image property set, and whose owner uuid is listed in the UI_IMAGE_LISTING_USERS Cyclades setting (in /etc/synnefo/20-snf-cyclades-app-ui.conf) will be displayed in a separate section in the installation wizard. The name of the new section will be the value of the LISTING_SECTION image property.

Virtual Servers

As mentioned, Cyclades uses Ganeti for management of VMs. The administrator can handle Cyclades VMs just like any other Ganeti instance, via gnt-instance commands. All Ganeti instances that belong to Synnefo, are separated from others, by a prefix in their names. This prefix is defined in BACKEND_PREFIX_ID setting in /etc/synnefo/20-snf-cyclades-app-backend.conf.

Apart from handling Cyclades VM at the Ganeti level, the administrator can also use the snf-manage server-* commands. These command cover the most common tasks that are relative with VM handling. Below we describe some of them, but for more information you can use the –help option of all snf-manage server-* commands. These command cover the most

The snf-manage server-create command can be used to create a new VM for some user. This command can be useful when the administrator wants to test Cyclades functionality without starting the API service, e.g. after an upgrade. Also, by using –backend-id option, the VM will be created in the specified backend, bypassing automatic VM allocation.

$ snf-manage server-create --flavor=1 --image=fc0f6858-f962-42ce-bf9a-1345f89b3d5e \
   --user=7cf4d078-67bf-424d-8ff2-8669eb4841ea --backend-id=2 \
   --password='example_passw0rd' --name='test_vm'

The above command will create a new VM for user 7cf4d078-67bf-424d-8ff2-8669eb4841ea in the Ganeti backend with ID 2. By default this command will issue a Ganeti job to create the VM (OP_INSTANCE_CREATE) and return. As in other commands, the –wait=True option can be used in order to wait for the successful completion of the job.

snf-manage server-list command can be used to list all the available servers. The command supports some useful options, like listing servers of a user, listing servers that exist in a Ganeti backend and listing deleted servers. Also, as in most of *-list commands, the –filter-by option can be used to filter the results. For example, the following command will only display the started servers of a specific flavor:

$ snf-manage server-list --filter-by="operstate=STARTED,flavor=<flavor_id>"

Another very useful command is the server-inspect command which will display all available information about the state of the server in DB and the state of the server in the Ganeti backend. The output will give you an easy overview about the state of the VM which can be useful for debugging.

Also the administrator can suspend a user’s VM, using the server-modify command:

$ snf-manage server-modify --suspended=True <server_id>

The user is forbidden to do any action on an administratively suspended VM, which is useful for abuse cases.

Ganeti backends

Since v0.11, Synnefo is able to manage multiple Ganeti clusters (backends) making it capable to scale linearly to tens of thousands of VMs. Backends can be dynamically added or removed via snf-manage commands.

Each newly created VM is allocated to a Ganeti backend by the Cyclades backend allocator. The VM is “pinned” to this backend, and can not change through its lifetime. The backend allocator decides in which backend to spawn the VM based on the available resources of each backend, trying to balance the load between them. Also, Networks are created to all Ganeti backends, in order to ensure that VMs residing on different backends can be connected to the same networks.

A backend can be marked as drained in order to be excluded from automatic servers allocation and not receive new servers. Also, a backend can be marked as offline to denote that the backend is not healthy (e.g. broken master) and avoid the penalty of connection timeouts.

Finally, Cyclades is able to manage Ganeti backends with different enabled hypervisors (kvm, xen), and different enabled disk templates.

Listing existing backends

To list all the Ganeti backends known to Synnefo, we run:

$ snf-manage backend-list
Adding a new Ganeti backend

Backends are dynamically added under the control of Synnefo with snf-manage backend-add command. In this section it is assumed that a Ganeti cluster, named is already up and running and configured to be able to host Synnefo VMs.

To add this Ganeti cluster, we run:

$ snf-manage backend-add --user="synnefo_user" --pass="synnefo_pass"

where clustername is the Cluster hostname of the Ganeti cluster, and user and pass are the credentials for the Ganeti RAPI user. All backend attributes can be also changed dynamically using the snf-manage backend-modify command.

snf-manage backend-add will also create all existing public networks to the new backend. You can verify that the backend is added, by running snf-manage backend-list.

Note that no VMs will be spawned to this backend, since by default it is in a drained state after addition in order to manually verify the state of the backend.

So, after making sure everything works as expected, make the new backend active by un-setting the drained flag. You can do this by running:

$ snf-manage backend-modify --drained=False <backend_id>
Allocation of VMs in Ganeti backends

As already mentioned, the Cyclades backend allocator is responsible for allocating new VMs to backends. This allocator does not choose the exact Ganeti node that will host the VM but just the Ganeti backend. The exact node is chosen by the Ganeti cluster’s allocator (hail).

The decision about which backend will host a VM is based on the available resources. The allocator computes a score for each backend, that shows its load factor, and the one with the minimum score is chosen. The admin can exclude backends from the allocation phase by marking them as drained by running:

$ snf-manage backend-modify --drained=True <backend_id>

The backend resources are periodically updated, at a period defined by the BACKEND_REFRESH_MIN setting, or by running snf-manage backend-update-status command. It is advised to have a cron job running this command at a smaller interval than BACKEND_REFRESH_MIN in order to remove the load of refreshing the backends stats from the VM creation phase.

Finally, the admin can decide to have a user’s VMs being allocated to a specific backend, with the BACKEND_PER_USER setting. This is a mapping between users and backends. If the user is found in BACKEND_PER_USER, then Synnefo allocates all his/hers VMs to the specific backend in the variable, even if is marked as drained (useful for testing).

Allocation based on disk-templates

Besides the available resources of each Ganeti backend, the allocator takes into consideration the disk template of the instance when trying to allocate it to a Ganeti backend. Specifically, the allocator checks if the flavor of the instance belongs to the available disk templates of each Ganeti backend.

A Ganeti cluster has a list of enabled disk templates (–enabled-disk-templates) and a list of allowed disk templates for new instances (–ipolicy-disk-templates). See the gnt-cluster manpage for more details about these options.

When Synnefo allocates an instance, it checks whether the disk template of the new instance belongs both in the enabled and ipolicy disk templates. You can see the list of the available disk-templates by running snf-manage backend-list. This list should be updated automatically after changing these options in Ganeti and it can also be updated by running snf-manage backend-update-status.

So the administrator, can route instances on different backends based on their flavor disk template, by modifying the enabled or ipolicy disk templates of each backend. Also, the administrator can route instances between different nodes of the same Ganeti backend, by modifying the same options at the nodegroup level (see gnt-group manpage for mor details).

Allocation based on custom allocator

In order to determine which ganeti cluster is best for allocating a virtual machine, the allocator uses two methods:

  • filter_backends
  • allocate

The filter_backends method is used to filter the backends that the allocator shouldn’t even consider. It takes two arguements:

  1. A list of the available backends. A backend is available if it is not drained or offline. Each backend is a django object and an instance of the Backend model.
  2. A map with 3 keys:
    • ram: The size of the memory we want to allocate on the backend.
    • disk: The size of the disk we want to allocate on the backend.
    • cpu: The size of the CPU we want to allocate on the backend.

The allocate method returns the backend that will be used to allocate the virtual machine. It takes two arguements:

  1. A list of the available backends. A backend is available if it is not drained or offline. Each backend is a django object and is an instance of the Backend model.

  2. A map with 3 keys:

    • ram: The size of the memory we want to allocate on the backend.
    • disk: The size of the disk we want to allocate on the backend.
    • cpu: The size of the CPU we want to allocate on the backend.

So the administrator can create his own allocation algorithm by creating a class that inherits the AllocatorBase located at synnefo.logic.allocators.base, and implements the above methods.

If the administrator wants synnefo to use his allocation algorithm he just has to change the BACKEND_ALLOCATOR_MODULE setting to the path of his allocator class.

Removing an existing Ganeti backend

In order to remove an existing backend from Synnefo, you must first make sure that there are not active servers in the backend, and then run:

$ snf-manage backend-remove <backend_id>

Virtual Networks

Cyclades also implements the Network service and exposes the Quantum Openstack API. Cyclades supports full IPv4 and IPv6 connectivity to the public internet for it’s VMs. Also, Cyclades provides L2 and L3 virtual private networks, giving the user freedom to create arbitraty network topologies of interconnected VMs.

Public networking is desployment specific and must be customized based on the specific needs of the system administrator. Private virtual networks can be provided by different network technologies which are exposed as different network flavors. For better understanding of networking please refer to the Network section.

A Cyclades virtual network is an isolated Layer-2 broadcast domain. A network can also have an associated IPv4 and IPv6 subnet representing the Layer-3 characteristics of the network. Each subnet represents an IP address block that is used in order to assign addresses to VMs.

To connect a VM to a network, a port must be created, which represent a virtual port on a network switch. VMs are connected to networks by attaching a virtual interface to a port.

Cyclades also supports floating IPs, which are public IPv4 addresses that can dynamically(hotplug-able) be added and removed to VMs. Floating IPs are a quotable resource that is allocated to each user. Unlike other cloud platforms, floating IPs are not implemented using 1-1 NAT to a ports private IP. Instead, floating IPs are directly assigned to virtual interfaces of VMs.

Exactly like VMS, networks can be handled as Ganeti networks via gnt-network commands. All Ganeti networks that belong to Synnefo are named with the prefix ${BACKEND_PREFIX_ID}-net-. Also, there are a number of snf-manage commands that can be used to handle networks, subnets, ports and floating IPs. Below we will present a use case scenario using some of these commands. For better understanding of these commands, refer to their help messages.

Create a virtual private network for user 7cf4d078-67bf-424d-8ff2-8669eb4841ea using the PHYSICAL_VLAN flavor, which means that the network will be uniquely assigned a physical VLAN. The network is assigned an IPv4 subnet, described by it’s CIDR and gateway. Also, the –dhcp=True option is used, to make nfdhcpd response to DHCP queries from VMs.

$ snf-manage network-create --user=7cf4d078-67bf-424d-8ff2-8669eb4841ea --name=prv_net-1 \
   --subnet= --gateway= --dhcp=True --flavor=PHYSICAL_VLAN

Inspect the state of the network in Cyclades DB and in all the Ganeti backends:

$ snf-manage network-inspect <network_id>

Inspect the state of the network’s subnet, containg an overview of the subnet’s IPv4 address allocation pool:

$ snf-manage subnet-inspect <subnet_id>

Connect a VM to the created private network. The port will automatically be assigned an IPv4 address from one of the network’s available IPs. This command will result in sending an OP_INSTANCE_MODIFY Ganeti command and attaching a NIC to the specified Ganeti instance.

$ snf-manage port-create --network=<network_id> --server=<server_id>

Inspect the state of the the port in Cyclades DB and in the Ganeti backend:

$ snf-manage port-inspect <port_id>

Disconnect the VM from the network and delete the network:

$ snf-manage port-remove <port_id>
$ snf-manage network-remove <network_id>
Enabling DHCP

When connecting a VM to a network, Cyclades will automatically assign an IPv4 address from the IPv4 or/and IPv6 subnets of the network. If the network has no subnets, then it will not be assigned any IP address.

If the network has DHCP enabled, then nfdhcpd daemon, which must be running on all Ganeti nodes, will respond to DHCP queries from VMs and assign to them the IP address that was allocated by Cyclades. DCHP can be enabled/disabled using the –dhcp option of network-create command.

Public network connectivity

Since v0.14, users are able to dynamically connect and disconnect their VMs from public networks. In order to do that, they have to use a floating IP. Floating IPs are basically public IPv4 addresses that can be dynamically attached and detached from VMs. The user creates a floating IP address from a network that has set the floating_ip_pool attribute. The floating IP is accounted to the user, who can then connect his VMs to public networks by creating ports that they are using this floating IP. Performing this work-flow from snf-manage would look like this:

$ snf-manage network-list --filter-by="floating_ip_pool=True"
id      name  user.uuid   state  public  subnet.ipv4  gateway.ipv4  drained  floating_ip_pool
 1  Internet       None  ACTIVE    True    False              True

$ snf-manage floating-ip-create --user=7cf4d078-67bf-424d-8ff2-8669eb4841ea --network=1

$ snf-manage floating-ip-list --user=7cf4d078-67bf-424d-8ff2-8669eb4841ea
id   address       network                             user.uuid  server
38             1  7cf4d078-67bf-424d-8ff2-8669eb4841ea      42

$ snf-manage port-create --user=7cf4d078-67bf-424d-8ff2-8669eb4841ea --network=1 \
                         --ipv4-address= --floating-ip=38

$ snf-manage port-list --user=7cf4d078-67bf-424d-8ff2-8669eb4841ea
id                            user.uuid        mac_address  network  server_id  fixed_ips   state
163 7cf4d078-67bf-424d-8ff2-8669eb4841ea  aa:00:00:45:13:98       1         77  ACTIVE

$ snf-manage port-remove 163
$ snf-manage floating-ip-remove 38

Users do not have permission to connect and disconnect VMs from public networks without using a floating IP address. However, the administrator have the ability to perform this tasks, using port-create and port-remove commands.

Network connectivity for newly created servers

When creating a virtual server, the user can specify the networks that the newly created server will be connected to. Beyond this, the administrator can define a list of networks that every new server will be forced to connect to. For example, you can enforce all VMs to be connected to a public network containing a metadata server. The networks must be specified in the CYCLADES_FORCED_SERVER_NETWORKS that exists in the /etc/synnefo/20-snf-cyclades-app-api.conf. For the networks in this setting, no access control or quota policy are enforced!

Finally, the administrator can define a list of networks that new servers will be connected, if the user has not specified networks in the request to create the server. Access control and quota policy are enforced, just as if the user had specified these networks. The list of these networks is defined in the CYCLADES_DEFAULT_SERVER_NETWORKS that exists in the /etc/synnefo/20-snf-cyclades-app-api.conf. This setting should only be used if Cyclades are being accessed by external clients that are unaware of the Neutron API extensions in the Compute API.

Each member of the above mentioned settings can be:

  • a network UUID
  • a tuple of network UUIDs: the server will be connected to only one of these networks, e.g. one that has a free IPv4 address
  • SNF:ANY_PUBLIC_IPV4: the server will be connected to any network with an IPv4 subnet defined
  • SNF:ANY_PUBLIC_IPV6: the server will be connected to any network with only an IPv6 subnet defined.
  • SNF:ANY_PUBLIC: the server will be connected to any public network.
Public IP accounting

There are many use cases, e.g. abuse ports, where you need to find which user or which server had a public IP address. For this reason, Cyclades keeps track usage of public IPv4/IPv6 addresses. Specifically, it keeps the date and time that each public IP address was allocated and released from a virtual server. This information can be found using ip-list command:

$ snf-manage ip-list

Show usage of a specific address:
$ snf-manage ip-list --address=

Show public IPs of a specific server:
$ snf-manage ip-list --server=<server_id>
Managing Network Resources

Proper operation of the Cyclades Network Service depends on the unique assignment of specific resources to each type of virtual network. Specifically, these resources are:

  • IP addresses. Cyclades creates a Pool of IPs for each Network, and assigns a unique IP address to each VM, thus connecting it to this Network. You can see the IP pool of each network by running snf-manage subnet-inspect <subnet_ID>. IP pools are automatically created and managed by Cyclades, depending on the subnet of the Network.
  • Bridges corresponding to physical VLANs, which are required for networks of type PRIVATE_PHYSICAL_VLAN.
  • One Bridge corresponding to one physical VLAN which is required for networks of type PRIVATE_MAC_PREFIX.
IPv4 addresses

An allocation pool of IPv4 addresses is automatically created for every network with an IPv4 subnet. By default, the allocation pool contains the range of IP addresses that are included in the subnet, except from the gateway and the broadcast address of the network. The range of IP addresses can be restricted using the –allocation-pool option of snf-manage network-create command. The admin can externally reserve IP addresses to exclude them from automatic allocation with the –add-reserved-ips option of snf-manage network-modify command. For example the following command will reserve two IP addresses from network with ID 42:

snf-manage network-modify --add-reserved-ips=, 42


Externally reserving IP addresses is also available at the Ganeti. However, when using Cyclades with multiple Ganeti backends, the handling of IP pools must be performed from Cyclades!


As already mentioned Cyclades use a pool of Bridges that must correspond to Physical VLAN at the Ganeti level. A bridge from the pool is assigned to each network of flavor PHYSICAL_VLAN. Creation of this pool is done using snf-manage pool-create command. For example the following command will create a pool containing the bridges from prv1 to prv21.

# snf-manage pool-create --type=bridge --base=prv --size=20

You can verify the creation of the pool, and check its contents by running:

# snf-manage pool-list
# snf-manage pool-show --type=bridge 1

Finally you can use the pool-modify management command in order to externally reserve the values from pool, extend or shrink the pool if possible.

MAC Prefixes

Cyclades also use a pool of MAC prefixes to assign to networks of flavor MAC_FILTERED. The handling of this pool is done exactly as with pool of bridges, except that the type option must be set to mac-prefix:

# snf-manage pool-create --type=mac-prefix --base=aa:00:0 --size=65536

The above command will create a pool of MAC prefixes from aa:00:1 to b9:ff:f. The MAC prefix pool is responsible for providing only unicast and locally administered MAC addresses, so many of these prefixes will be externally reserved, to exclude from allocation.


The handling of quotas for Cyclades resources is powered by Astakos quota mechanism. During registration of Cyclades service to Astakos, the Cyclades resources are also imported to Astakos for accounting and presentation.

Upon a request that will result in a resource creation or removal, Cyclades will communicate with Astakos to ensure that user quotas are within limits and update the corresponding usage. If a limit is reached, the request will be denied with an overLimit(413) fault.

The resources that are exported by Cyclades are the following:

  • cyclades.vm: Number of virtual machines
  • cyclades.total_cpu: Number of virtual machine processors
  • cyclades.cpu: Number of virtual machine processors of running VMs
  • cyclades.total_ram: Virtual machine memory size
  • cyclades.ram: Virtual machine memory size of running VMs
  • cyclades.disk: Virtual machine disk size
  • cyclades.floating_ip: Number of floating IP addresses
  • Number of private virtual networks

Enforcing quotas

User quota can get overlimit, for example when a user is removed from a project granting Cyclades resources. However, no action is automatically taken to restrict users to their new limits. There is a special tool for quota enforcement:

# snf-manage enforce-resources-cyclades

This command will check and report which users are overlimit on their Cyclades quota; it will also suggest actions to be taken in order to enforce quota limits, dependent on the overlimit resource:

  • cyclades.vm: Delete VMs
  • cyclades.total_cpu: Delete VMs
  • cyclades.cpu: Shutdown VMs
  • cyclades.total_ram: Delete VMs
  • cyclades.ram: Shutdown VMs
  • cyclades.disk: Delete volumes (may also trigger VM deletion)
  • cyclades.floating_ip: Detach and delete IPs

VMs to be deleted/shutdown are chosen first by state in the following order: ERROR, BUILD, STOPPED, STARTED or RESIZE and then by decreasing ID. When needing to remove IPs, we first choose IPs that are free, then those attached to VMs, using the same VM ordering.

You need to specify the resources to be checked, using the option --resources. A safe first attempt would be to specify cyclades.cpu,cyclades.ram, that is, to check the less dangerous resources, those that do not result in deleting any VM, volume, or IP.

If you want to handle overlimit quota in a safer way for resources that would normally trigger a deletion, you can use the option --soft-resources. Enforcing e.g. cyclades.vm in a “soft” way will shutdown the VMs rather than deleting them. This is useful as an initial warning for a user who is overquota; but notice that the user may restart their shutdown VMs, if the resources that control starting VMs allows them to do so.

With option --list-resources you can inspect the available resources along with the related standard and soft enforce actions. It is also possible to specify users and projects to be checked or excluded.

Actual enforcement is done with option --fix. In order to control the load that quota enforcement may cause on Cyclades, one can limit the number of operations per backend. For example,

# snf-manage enforce-resources-cyclades --fix --max-operations 10

will apply only the first 10 listed actions per backend. One can repeat the operation, until nothing is left to be done.

To control load a timeout can also be set for shutting down VMs (using option --shutdown-timeout <sec>). This may be needed to avoid expensive operations triggered by shutdown, such as Windows updates.

The command outputs the list of applied actions and reports whether each action succeeded or not. Failure is reported if for any reason cyclades failed to process the job and submit it to the backend.

Shared Resources

Since version 0.17, it is possible to share resources among the members of the project that the resource belongs to.

The owner of the resource can choose to grant full access to all users that are members of the project that the resource is charged to. Users will be able to see the resource and use it exactly as if they were the owners of the resource. For example, users will be able to restart or destroy a shared virtual server.

The sharing mechanism suppports fine-grained granularity at the resource level, which means that you can share a resource (e.g. virtual server) without sharing related resources (e.g. volumes, floating IPs, etc.). This results to what we call “ghost resources”, which are resources that are visible to a user only because they are somehow related with a shared resource, and the user has no access to them. For example, after sharing a volume that is attached to some server, project members will be able to see the server that the volume is attached to, but they will not have any access to the server.

This is an optional feature which is by default disabled. To enable the sharing functionality, the administrator must set the CYCLADES_SHARED_RESOURCES_ENABLE setting in /etc/synnefo/20-snf-cyclades-app-api.conf to True. After this, users will be able to grant/remove access from resources from the project reassign view in the web UI.

Cyclades advanced operations

Reconciliation mechanism

Cyclades - Ganeti reconciliation

On certain occasions, such as a Ganeti or RabbitMQ failure, the state of Cyclades database may differ from the real state of VMs and networks in the Ganeti backends. The reconciliation process is designed to synchronize the state of the Cyclades DB with Ganeti. There are two management commands for reconciling VMs and Networks that will detect stale, orphans and out-of-sync VMs and networks. To fix detected inconsistencies, use the –fix-all option.

$ snf-manage reconcile-servers
$ snf-manage reconcile-servers --fix-all

$ snf-manage reconcile-networks
$ snf-manage reconcile-networks --fix-all

Please see snf-manage reconcile-servers --help and snf-manage reconcile--networks --help for all the details.

Cyclades - Astakos reconciliation

As already mentioned, Cyclades communicates with Astakos for resource accounting and quota enforcement. In rare cases, e.g. unexpected failures, the two services may get unsynchronized. For this reason there are the reconcile-commissions-cyclades and reconcile-resources-cyclades command that will synchronize the state of the two services. The first command will detect any pending commissions, while the second command will detect that the usage that is reported by Astakos is correct. To fix detected inconsistencies, use the –fix option.

$ snf-manage reconcile-commissions-cyclades
$ snf-manage reconcile-commissions-cyclades --fix

$ snf-manage reconcile-resources-cyclades
$ snf-manage reconcile-resources-cyclades --fix
Cyclades resources reconciliation

Reconciliation of pools will check the consistency of available pools by checking that the values from each pool are not used more than once, and also that the only reserved values in a pool are the ones used. Pool reconciliation will check pools of bridges, MAC prefixes, and IPv4 addresses for all networks. To fix detected inconsistencies, use the –fix option.

$ snf-manage reconcile-pools
$ snf-manage reconcile-pools --fix

snf-vncauthproxy configuration

Since snf-vncauthproxy-1.6 and snf-cyclades-app-0.16, it is possible to run snf-vncauthproxy on a separate node and have multiple snf-vncauthproxy instances / nodes, to serve clients.

The CYCLADES_VNCAUTHPROXY_OPTS setting has become a list of dictionaries, each of which defines one snf-vncauthproxy instance. Each vncauthproxy should be properly configured to accept control connections by the Cylades host (via the --listen-address CLI parameter of snf-vncauthproxy) and VNC connections from clients (via the --proxy-listen-address CLI parameter.

For a two-node vncauthproxy setup, the CYCLADES_VNCAUTHPROXY_OPTS would look like:

    'auth_user': 'synnefo',
    'auth_password': 'secret_password',
    'server_address': '',
    'server_port': 24999,
    'enable_ssl': True,
    'ca_cert': '/path/to/cacert',
    'strict': True,
    'auth_user': 'synnefo',
    'auth_password': 'secret_password',
    'server_address': '',
    'server_port': 24999,
    'enable_ssl': False,
    'ca_cert': '/path/to/cacert',
    'strict': True,

The server_address is the host / IP which Cyclades will use for the control connection, in order to set up the forwarding.

The vncauthproxy DAEMON_OPTS option in /etc/default/vncauthproxy would look like:


The --proxy-listen-address is the host / IP which clients (Web browsers / VNC clients) will use to connect to snf-vncauthproxy.

In case that snf-vncauthproxy doesn’t run on the same node as the Cyclades node, it is highly recommended to enable SSL on the control socket, using strict verification of the server certificate. The only caveat, for the time being, is that the same certificate, provided to snf-vncauthproxy, is used for both the control and the client connections. If the control and client host (--listen-address and --proxy-listen-address parameters, respectively) differ, you should make sure to generate a certificate covering both (using the one as common name / CN, and specifying the other as a subject alternative name).

VM stats collecting

snf-cyclades-gtools comes with a collectd plugin to collect CPU and network stats for Ganeti VMs and an example collectd configuration. snf-stats-app is a Django (snf-webproject) app that serves the VM stats graphs by reading the VM stats (from RRD files) and serves graphs.

The snf-stats-app was originally written by GRNET NOC as a WSGI Python app and was ported to a Synnefo (snf-webproject) app.

snf-stats-app configuration

The snf-stats-app node should have collectd installed. The collectd configuration should enable the network plugin, assuming the server role, and the RRD plugin / backend, to store the incoming stats. Your /etc/collectd/collectd.conf should look like:

FQDNLookup true
LoadPlugin syslog
<Plugin syslog>
    LogLevel info

LoadPlugin network
LoadPlugin rrdtool
<Plugin network>
    TimeToLive 128
    <Listen "" "25826">
        SecurityLevel "Sign"
        AuthFile "/etc/collectd/passwd"

    ReportStats false
    MaxPacketSize 65535

<Plugin rrdtool>
    DataDir "/var/lib/collectd/rrd"
    CacheTimeout 120
    CacheFlush 900
    WritesPerSecond 30
    RandomTimeout 0

Include "/etc/collectd/filters.conf"
Include "/etc/collectd/thresholds.conf"

An example collectd config file is provided in /usr/share/doc/snf-stats-app/examples/stats-colletcd.conf.

The recommended deployment is to run snf-stats-app using gunicorn with an Apache2 or nginx reverse proxy (using the same configuration as the other Synnefo services / apps). An example gunicorn config file is provided in /usr/share/doc/snf-stats-app/examples/stats.gunicorn.

Make sure to edit the settings under /etc/synnefo/20-snf-stats-app-settings.conf to match your deployment. More specifically, you should change the STATS_BASE_URL setting (refer to previous documentation on the BASE_URL settings used by the other Synnefo services / apps) and the RRD_PREFIX and GRAPH_PREFIX settings.

You should also set the STATS_SECRET_KEY to a random string and make sure it’s the same at the CYCLADES_STATS_SECRET_KEY on the Cyclades host (see below).

RRD_PREFIX is the directory where collectd stores the RRD files. The default setting matches the default RRD directory for the collectd RRDtool plugin. In a more complex setup, the collectd daemon could run on a separate host and export the RRD directory to the snf-stats-app node via e.g. NFS.

GRAPH_PREFIX is the directory where collectd stores the resulting stats graphs. You should create it manually, in case it doesn’t exist.

# mkdir /var/cache/snf-stats-app/
# chown www-data:wwwdata /var/cache/snf-stats-app/

The snf-stats-app will typically run as the www-data user. In that case, make sure that the www-data user should have read access to the RRD_PREFIX directory and read / write access to the GRAPH_PREFIX directory.

snf-stats-app, based on the STATS_BASE_URL setting will export the following URL ‘endpoints`:

  • CPU stats bar: STATS_BASE_URL/v1.0/cpu-bar/<encrypted VM hostname>
  • Network stats bar: STATS_BASE_URL/v1.0/net-bar/<encrypted VM hostname>
  • CPU stats daily graph: STATS_BASE_URL/v1.0/cpu-ts/<encrypted VM hostname>
  • Network stats daily graph: STATS_BASE_URL/v1.0/net-ts/<encrypted VM hostname>
  • CPU stats weekly graph: STATS_BASE_URL/v1.0/cpu-ts-w/<encrypted VM hostname>
  • Network stats weekly graph: STATS_BASE_URL/v1.0/net-ts-w/<encrypted VM hostname>

You can verify that these endpoints are exported by issuing:

# snf-manage show_urls
snf-cyclades-gtools configuration

To enable VM stats collecting, you will need to:

  • Install collectd on every Ganeti (VM-capable) node.

  • Enable the Ganeti stats plugin in your collectd configuration. This can be achieved by either copying the example collectd conf file that comes with snf-cyclades-gtools (/usr/share/doc/snf-cyclades-gtools/examples/ganeti-stats-collectd.conf) or by adding the following line to your existing (or default) collectd conf file:

    Include /etc/collectd/ganeti-stats.conf

    In the latter case, make sure to configure collectd to send the collected stats to your collectd server (via the network plugin). For more details on how to do this, check the collectd example config file provided by the package and the collectd documentation.

snf-cyclades-app configuration

At this point, stats collecting should be enabled and working. You can check that everything is ok by checking the contents of /var/lib/collectd/rrd/ directory (it will gradually get populated with directories containing RRD files / stats for every Synnefo instances).

You should also check that gunicorn and Apache2 are configured correctly by accessing the graph URLs for a VM (whose stats have been populated in /var/lib/collectd/rrd).

Cyclades uses the CYCLADES_STATS_SECRET_KEY setting in 20-snf-cyclades-app to encrypt the instance hostname in the stats graph URL. This settings should be set to a random value and match the STATS_SECRET_KEY on the Stats host.

Cyclades (snf-cyclades-app) fetches the stat graphs for VMs based on four settings in 20-snf-cyclades-app-api.conf. The settings are:

Make sure that you change this settings to match your STATS_BASE_URL (and generally the Apache2 / gunicorn deployment on your stats host).

Cyclades will pass these URLs to the Cyclades UI and the user’s browser will fetch them when needed.


The Helpdesk application provides the ability to view the virtual servers and networks of all users, along with the ability to perform some basic actions like administratively suspending a server. You can perform look-ups by user UUID or email, by server ID (vm-$id) or by an IPv4 address.

If you want to activate the helpdesk application you can set to True the HELPDESK_ENABLED setting. Access to helpdesk views (under $BASE_URL/helpdesk) is only allowed to users that belong to Astakos groups defined in the HELPDESK_PERMITTED_GROUPS setting, which by default contains the helpdesk group. For example, to allow <user_id> to access helpdesk view, you should run the following command in the Astakos node:

snf-manage group-add helpdesk
snf-manage user-modify --add-group=helpdesk <user_id>

Cyclades internals

Asynchronous communication with Ganeti backends

Synnefo uses Google Ganeti backends for VM cluster management. In order for Cyclades to be able to handle thousands of user requests, Cyclades and Ganeti communicate asynchronously. Briefly, requests are submitted to Ganeti through Ganeti’s RAPI/HTTP interface, and then asynchronous notifications about the progress of Ganeti jobs are being created and pushed upwards to Cyclades. The architecture and communication with a Ganeti backend is shown in the graph below:


The Cyclades API server is responsible for handling user requests. Read-only requests are directly served by looking up the Cyclades DB. If the request needs an action in the Ganeti backend, Cyclades submit jobs to the Ganeti master using the Ganeti RAPI interface.

While Ganeti executes the job, snf-ganeti-eventd, and snf-progress-monitor are monitoring the progress of the job and send corresponding messages to the RabbitMQ servers. These components are part of snf-cyclades-gtools and must be installed on all Ganeti nodes. Specially:

  • snf-ganeti-eventd sends messages about operations affecting the operating state of instances and networks. Works by monitoring the Ganeti job queue.
  • snf-progress_monitor sends messages about the progress of the Image deployment phase which is done by the Ganeti OS Definition snf-image.

Finally, snf-dispatcher consumes messages from the RabbitMQ queues, processes these messages and properly updates the state of the Cyclades DB. Subsequent requests to the Cyclades API, will retrieve the updated state from the DB.

Admin Dashboard (Admin)


Admin is the Synnefo component that provides to trusted users the ability to manage and view various different Synnefo entities such as users, VMs, projects etc. Additionally, it automatically generates charts and statistics using data from the Astakos/Cyclades stats.

Access and permissions

The Admin dashboard can be accessed by default from the ADMIN_BASE_URL URL. Since there is no login form, the user must login on Astakos first and then visit the above URL. Access will be granted only to users that belong to a predefined list of Astakos groups. By default, there are three group categories that are mapped 1-to-1 to Astakos groups:

  • ADMIN_READONLY_GROUP: ‘admin-readonly’
  • ADMIN_HELPDESK_GROUP: ‘helpdesk’
  • ADMIN_GROUP: ‘admin’

The group categories can be changed using the ADMIN_PERMITTED_GROUPS setting. In order to change the Astakos group that a category corresponds to, the administrator can specify the group that he/she wants in the ADMIN_READONLY_GROUP, ADMIN_HELPDESK_GROUP or ADMIN_GROUP settings.

Note that while any user that belongs to the ADMIN_PERMITTED_GROUPS has the same access to the administrator dashboard, the actions that are allowed for a group may differ. That’s because Admin implements a Role-Based Access Control (RBAC) policy, which can be changed from the ADMIN_RBAC setting. By default, users in the ADMIN_READONLY_GROUP cannot perform any actions. On the other hand, users in the ADMIN_GROUP can perform all actions. In the middle of the spectrum is the ADMIN_HELPDESK_GROUP, which by default performs a small subset of reversible actions.

Seting up Admin

Admin is bundled by default with a list of sane settings. The most important one, ADMIN_ENABLED, is set to True and defines whether Admin will be used or not.

The administrator simply has to create the necessary Astakos groups and add trusted users in them. The following example will create an admin group and will add a user in it:

snf-manage group-add admin
snf-manage user-modify --add-group=admin <user_id>

Finally, the administrator must edit the 20-snf-admin-app-general.conf settings file, uncomment the ADMIN_BASE_URL setting and assign the appropriate URL to it. In most cases, this URL will be the top-level URL of the Admin node, with the optional addition of an extra path (e.g. /admin) in order to distinguish it from different components.

That’s all that is required for a single-node setup. For a multi-node setup, please consult the following section:

Multi-node Setup

Admin by design does not use the Astakos/Cyclades API for any action. Instead, it requires direct access to the Astakos/Cyclades database as well as the settings of their nodes. As a result, when installing Admin in a node, the Astakos and Cyclades packages will also be installed.

In order to disable the Astakos/Cyclades API in the Admin node, the administrator can add the following line in 99-local.conf (you can create it if doesn’t exist):


Note that the above change does not interfere with the ADMIN_BASE_URL, which will be used normally.

Furthermore, if Astakos and Cyclades have separate databases, then they must be defined in the DATABASES setting of 10-snf-webproject-database.conf. An example setup is the following:

    'default': {
        'ENGINE': 'django.db.backends.postgresql_psycopg2',
        'NAME': 'snf_apps_cyclades',
        'HOST': <Cyclades host>,
    }, 'cyclades': {
        'ENGINE': 'django.db.backends.postgresql_psycopg2',
        'NAME': 'snf_apps_cyclades',
        'HOST': <Cyclades host>,
    }, 'astakos': {
        'ENGINE': 'django.db.backends.postgresql_psycopg2',
        'NAME': 'snf_apps_astakos',
        'HOST': <Astakos host>,

DATABASE_ROUTERS = ['snf_django.utils.routers.SynnefoRouter']

You may notice that there are three databases instead of two. That’s because Django requires that every DATABASES setting has a default database. In our case, we suggest that you use as default the Cyclades database.

You should also make sure not to enable database (psycopg) connection pooling (as described in the installation guide) by omitting (deleting or commenting out) all the relevant pooling options from the DB configuration (i.e. the synnefo_poolsize option).

Finally, you must not forget to add the DATABASE_ROUTERS setting in the above example that must always be used in multi-db setups.

Disabling Admin

The easiest way to disable the Admin Dashboard is to set the ADMIN_ENABLED setting to False.

Synnefo management commands (“snf-manage”)

Each Synnefo service, Astakos, Pithos and Cyclades is controlled by the administrator using the “snf-manage” admin tool. This tool is an extension of the Django command-line management utility. It is run on the host that runs each service and provides different types of commands depending on the services running on the host. If you are running more than one service on the same host “snf-manage” adds all the corresponding commands for each service dynamically, providing a unified admin environment.

To run “snf-manage” you just type:

# snf-manage <command> [arguments]

on the corresponding host that runs the service. For example, if you have all services running on different physical hosts you would do:

root@astakos-host # snf-manage <astakos-command> [argument]
root@pithos-host # snf-manage <pithos-command> [argument]
root@cyclades-host # snf-manage <cyclades-command> [argument]

If you have all services running on the same host you would do:

root@synnefo-host # snf-manage <{astakos,pithos,cyclades}-command> [argument]

Note that you cannot execute a service’s command on a host that is not running this service. For example, the following will return an error if Astakos and Cyclades are installed on different physical hosts:

root@astakos-host # snf-manage <cyclades-command> [argument]
Unknown command: 'cyclades-command'
Type 'snf-manage help' for usage.

This is the complete list of “snf-manage” commands for each service.

Astakos snf-manage commands

Name Description
fix-superusers Transform superusers created by syncdb into AstakosUser instances
cleanup-full Cleanup sessions and session catalog
commission-list List pending commissions
commission-show Show details for a pending commission
component-add Register a component
component-list List components
component-modify Modify component attributes
component-show Show component details
project-control Manage projects and applications
project-list List projects
project-show Show project details
quota-list List user quota
quota-verify Check the integrity of user quota
reconcile-resources-astakos Reconcile resource usage of Quotaholder with Astakos DB
resource-list List resources
resource-modify Modify a resource’s default base quota and boolean flags
service-export-astakos Export Astakos services and resources in JSON format
service-import Register services
service-list List services
service-show Show service details
term-add Add approval terms
user-activation-send Send user activation
user-add Add user
authpolicy-add Create a new authentication provider policy profile
authpolicy-list List existing authentication provider policy profiles
authpolicy-remove Remove an authentication provider policy
authpolicy-set Assign an existing authentication provider policy profile to a user or group
authpolicy-show Show authentication provider profile details
group-add Create a group with the given name
group-list List available groups
user-list List users
user-modify Modify user
user-show Show user details
oauth2-client-add Create an oauth2 client
oauth2-client-list List oauth2 clients
oauth2-client-remove Remove an oauth2 client along with its registered redirect urls

Pithos snf-manage commands

Name Description
reconcile-commissions-pithos Display unresolved commissions and trigger their recovery
service-export-pithos Export Pithos services and resources in JSON format
reconcile-resources-pithos Detect unsynchronized usage between Astakos and Pithos DB resources and synchronize them if specified so.
file-show Display object information

Cyclades snf-manage commands

Name Description
backend-add Add a new Ganeti backend
backend-list List backends
backend-modify Modify a backend
backend-update-status Update backend statistics for instance allocation
backend-remove Remove a Ganeti backend
enforce-resources-cyclades Check and fix quota violations for Cyclades resources
server-create Create a new server
server-show Show server details
server-list List servers
server-modify Modify a server
server-import Import an existing Ganeti VM into synnefo
server-inspect Inspect a server in DB and Ganeti
network-create Create a new network
network-list List networks
network-modify Modify a network
network-inspect Inspect network state in DB and Ganeti
network-remove Delete a network
flavor-create Create a new flavor
flavor-list List flavors
flavor-modify Modify a flavor
volume-type-create Create a new volume type
volume-type-list List volume types
volume-type-show Show volume type details
volume-type-modify Modify a volume type
image-list List images
image-show Show image details
pool-create Create a bridge or mac-prefix pool
pool-show Show pool details
pool-list List pools
pool-modify Modify a pool
pool-remove Delete a pool
port-create Create a port connecting a server to a network
port-inspect Inspect the state of a port in DB and Ganeti
port-list List ports
port-remove Delete a port
floating-ip-create Create a new floating IP
floating-ip-attach Attach a floating IP to a server
floating-ip-detach Detach a floating IP from a server
floating-ip-list List floating IPs
floating-ip-remove Delete a floating IP
queue-inspect Inspect the messages of a RabbitMQ queue
queue-retry Resend messages from Dead Letter queues to original exchanges
service-export-cyclades Export Cyclades services and resources in JSON format
subnet-create Create a subnet
subnet-inspect Inspect a subnet in DB
subnet-list List subnets
subnet-modify Modify a subnet
reconcile-servers Reconcile servers of Synnefo DB with state of Ganeti backend
reconcile-networks Reconcile networks of Synnefo DB with state of Ganeti backend
reconcile-pools Check consistency of pool resources
reconcile-commissions-cyclades Detect and resolve pending commissions to Quotaholder
reconcile-resources-cyclades Reconcile resource usage of Astakos with Cyclades DB.

Astakos helper scripts

Astakos includes two scripts to facilitate the installation procedure. Running:

snf-component-register [<component_name>]

automates the registration of the standard Synnefo components (Astakos, Cyclades, and Pithos) in Astakos database. It internally uses the script:

snf-service-export <component_name> <base_url>

which simulates the export of service and resource definitions of the standard Synnefo components.

Pithos managing accounts

Pithos provides a utility tool for managing accounts. To run you just type:

# pithos-manage-accounts <command> [arguments]

This is the list of the available commands:

Name Description
delete Remove an account from the Pithos DB
export-quota Export account quota in a file
list List existing/duplicate accounts
merge Move an account contents in another account
set-container-quota Set container quota for all or a specific account

The “kamaki” API client

To upload, register or modify an image you will need the kamaki tool. Before proceeding make sure that it is configured properly. Verify that url and token are set as needed:

$ kamaki config list

To change a setting use kamaki config set:

$ kamaki config set cloud.default.url
$ kamaki config set cloud.default.token ...

To test that everything works, try authenticating the current account with kamaki:

$ kamaki user authenticate

This will output user information.

Upload Image

By convention, images are stored in a container called images. Check if the container exists, by listing all containers in your account:

$ kamaki file list /images

If the container images does not exist, create it:

$ kamaki container create images

You are now ready to upload an image to container images. You can upload it with a Pithos client, or use kamaki directly:

$ kamaki file upload ubuntu.iso /images

You can use any Pithos client to verify that the image was uploaded correctly, or you can list the contents of the container with kamaki:

$ kamaki file list /images

The full Pithos URL for the previous example will be pithos://u53r-un1qu3-1d/images/ubuntu.iso where u53r-un1qu3-1d is the unique user id (uuid).

Register Image

To register an image you will need to use the full or the relative Pithos URL. To register as a public image the one from the previous example use:

$ kamaki image register --name=Ubuntu --location=/images/ubuntu.iso --public

The --public flag is important, if missing the registered image will not be listed by kamaki image list.

Use kamaki image register with no arguments to see a list of available options. A more complete example would be the following:

$ kamaki image register --name Ubuntu --location /images/ubuntu.iso \
         --public --disk-format diskdump --property kernel=3.1.2

To verify that the image was registered successfully use:

$ kamaki image list --name-like ubuntu



Since Synnefo v0.14, you are able to adapt the Astakos, Pithos and Cyclades Web UI to your company’s visual identity. This is possible using the snf-branding component, which is automatically installed on the nodes running the API servers for Astakos, Pithos and Cyclades.


This can be done by modifing the settings provided by the snf-branding component to match your service identity. The settings for the snf-branding application can be found inside the configuration file /etc/synnefo/15-snf-branding.conf on the nodes that have Astakos, Pithos and Cyclades installed.

By default, the global service name is “Synnefo” and the company name is “GRNET”. These names and their respective logos and URLs are used throughout the Astakos, Pithos and Cyclades UI.

Names and URLs:

The first group of branding customization refers to the service’s and company’s information.

You can overwrite the company and the service name and URL respectively by uncommenting and setting the following:

# setting used in Astakos Dashboard/Projects pages

# settings used in Astakos, Pithos, Cyclades footer only if

Copyright and footer options:

By default, no Copyright message is shown in the UI footer. If you want to make it visible in the footer of Astakos, Pithos and Cyclades UI, you can uncomment and set to True the BRANDING_SHOW_COPYRIGHT setting:


Copyright message defaults to ‘Copyright (c) 2011-<current_year> <BRANDING_COMPANY_NAME>.’ but you can overwrite it to a completely custom one by setting the following option:

BRANDING_COPYRIGHT_MESSAGE = 'Copyright (c) 2011-2013 GRNET'

If you want to include a custom message in the footer, you can uncomment and set the BRANDING_FOOTER_EXTRA_MESSAGE setting. You can use html markup. Your custom message will appear above Copyright message at the Compute templates and the Dashboard UI.



The Astakos, Pithos and Cyclades Web UI has some logos and images.

The branding-related images are presented in the following table:

Image Name/extension convention Usage
Favicon favicon.ico Favicon for all services
Dashboard logo dashboard_logo.png Visible in all Astakos UI pages
Cloudbar icon cloudbar_home.png Homepage icon for admin & cloudbar
Compute logo compute_logo.png Visible in all Cyclades UI pages
Console logo console_logo.png Visible in the Cyclades Console Window
Storage logo storage_logo.png Visible in all Pithos UI pages

There are two methods available for replacing all, or individual, branding-related images:

  1. Create a new directory inside /usr/share/synnefo/static/ (e.g. mybranding) and place there some or all of your images.

    If you want to replace all of your images, keep the name/extension conventions as indicated in the above table and change the BRANDING_IMAGE_MEDIA_URL setting accordingly:

    # using relative path
    BRANDING_IMAGE_MEDIA_URL= '/static/mybranding/images/'
    # or if you already host them in a separate domain (e.g. cdn)

    If you wish to replace individual images, do not uncomment BRANDING_IMAGE_MEDIA_URL, but instead provide a relative path, pointing to the file inside your directory for each BRANDING_<image>_URL that you wish to replace.

  2. Upload some or all of your images to a server and replace each BRANDING_<image>_URL with the absolute url of the image (i.e. BRANDING_DASHBOARD_URL = '').

    Note that the alternative text for each image tag inside html documents is alt=“BRANDING_SERVICE_NAME {Dashboard, Compute. Console, Storage}” respectively.


Retina optimized images:

Synnefo UI is optimized for Retina displays. As far as images are concerned, retina.js is used.

Retina.js checks each image on a page to see if there is a high-resolution version of that image on your server. If a high-resolution variant exists, the script will swap in that image in-place.

The script assumes you use Apple’s prescribed high-resolution modifier (@2x) to denote high-resolution image variants on your server.

For each of the images that you wish the script to replace, you must have a high-resolution variant in the same folder named correctly and it will be detected automatically. For example if your image is in <my_directory> and is named “my_image.jpg” the script will look in the same directory for an image named “my_image@2x.jpg”.

In case that you don’t want to use a high-resolution image, the normal-resolution image will be visible.

More branding

Although, it is not 100% branding-related, further verbal customization is feasible.


The output of all email *.txt files will be already customized to contain your company and service names but you can further alter their content if you feel it best fits your needs.

In order to overwrite one or more email-templates you need to place your modified <email-file>.txt files respecting the following structure:


Feel free to omit any of the above files you do not wish to overwrite.

Below is a list of all the emails sent by Synnefo to users along with a short description and a link to their content:

  • snf-astakos-app/astakos/im/templates/im/email.txt Base email template. Contains a contact email and a “thank you” message. (Link)
  • snf-astakos-app/astakos/im/templates/im/activation_email.txt Email sent to user that prompts him/her to click on a link provided to activate the account. Extends “email.txt” (Link)
  • snf-astakos-app/astakos/im/templates/im/invitation.txt Email sent to an invited user. He/she has to click on a link provided to activate the account. Extends “email.txt” (Link)
  • snf-astakos-app/astakos/im/templates/im/switch_accounts_email.txt Email sent to user upon his/her request to associate this email address with a shibboleth account. He/she has to click on a link provided to activate the association. Extends “email.txt” (Link)
  • snf-astakos-app/astakos/im/templates/im/welcome_email.txt Email sent to inform the user that his/ her account has been activated. Extends “email.txt” (Link)
  • snf-astakos-app/astakos/im/templates/registration/email_change_email.txt Email sent to user when he/she has requested new email address assignment. The user has to click on a link provided to validate this action. Extends “email.txt” (Link)
  • snf-astakos-app/astakos/im/templates/registration/password_email.txt Email sent for resetting password purpose. The user has to click on a link provided to validate this action. Extends “email.txt” (Link)
  • snf-astakos-app/astakos/im/templates/im/projects/project_approval_notification.txt Informs the project owner that his/her project has been approved. Extends “email.txt” (Link)
  • snf-astakos-app/astakos/im/templates/im/projects/project_denial_notification.txt Informs the project owner that his/her project application has been denied explaining the reasons. Extends “email.txt” (Link)
  • snf-astakos-app/astakos/im/templates/im/projects/project_membership_change_notification.txt An email is sent to a user containing information about his project membership (whether he has been accepted, rejected or removed). Extends “email.txt” (Link)
  • snf-astakos-app/astakos/im/templates/im/projects/project_membership_enroll_notification.txt Informs a user that he/she has been enrolled to a project. Extends “email.txt” (Link)
  • snf-astakos-app/astakos/im/templates/im/projects/project_membership_leave_request_notification.txt An email is sent to the project owner to make him aware of a user having requested to leave his project. Extends “email.txt” (Link)
  • snf-astakos-app/astakos/im/templates/im/projects/project_membership_request_notification.txt An email is sent to the project owner to make him/her aware of a user having requested to join his project. Extends “email.txt” (Link)
  • snf-astakos-app/astakos/im/templates/im/projects/project_suspension_notification.txt An email is sent to the project owner to make him/her aware of his/her project having been suspended. Extends “email.txt” (Link)
  • snf-astakos-app/astakos/im/templates/im/projects/project_termination_notification.txt An email is sent to the project owner to make him/her aware of his/her project having been terminated. Extends “email.txt” (Link)


Django templates language:

If you choose to overwrite these email templates, be mindful of the necessary information contained in django template variables that must not be omitted, such as the activation link for activating one’s account and many more. These variables are contained into {{}} inside the templates.

Astakos landing page

Astakos generates sensible default values used to display component- specific details in several places across views (dashboard, cloudbar etc.). One of these places is Astakos landing page where Synnefo components are featured.

In case those values doesn’t seem to suit your deployment, Astakos allows you to override any of them using ASTAKOS_COMPONENTS_META setting in your /etc/synnefo/20-snf-astakos-app-settings.conf configuration file.

So, for example if you want to add your own image for Astakos service and in the same time hide Cyclades service from Astakos landing page you can add the following line to your configuration file:

  'astakos': {
    'dashboard': {
      'icon': '<path-to-your-icon>'
  'cyclades': {
    'dashboard': {
      'show': False

A complete list of available keys is shown below:

'<component-name>' = {
  'order': 1,
  'dashboard': {
    'order': 1,
    'show': True,
    'description': '<component-description>',
    'icon': '<component-icon-path>',
  'cloudbar': {
    'show': True

403, 404 and 500 pages

Feel free to add your own 403 (HTTP Forbidden), 404 (Page not found) and 500 (server error) pages. To override the default Synnefo error views, you must write and include any of the files 403.html, 404.html and 500.html in your /etc/synnefo/templates/ directory.

Their content is up to you, but you may use as guides the default error pages found in:


RabbitMQ Broker

Queue nodes run the RabbitMQ sofware, which provides AMQP functionality. To guarantee high-availability, more than one Queue nodes should be deployed, each of them belonging to the same RabbitMQ cluster. Synnefo uses the RabbitMQ active/active High Available Queues which are mirrored between two nodes within a RabbitMQ cluster.

The RabbitMQ nodes that form the cluster, are declared to Synnefo through the AMQP_HOSTS setting. Each time a Synnefo component needs to connect to RabbitMQ, one of these nodes is chosen in a random way. The client that Synnefo uses to connect to RabbitMQ, handles connection failures transparently and tries to reconnect to a different node. As long as one of these nodes is up and running, functionality of Synnefo should not be downgraded by the RabbitMQ node failures.

All the queues that are being used are declared as durable, meaning that messages are persistently stored to RabbitMQ, until they get successfully processed by a client.

Currently, RabbitMQ is used by the following components:

  • snf-ganeti-eventd and snf-progress-monitor: These components send messages concerning the status and progress of jobs in the Ganeti backend.
  • snf-dispatcher: This daemon, consumes the messages that are sent from the above components, and updates the Cyclades DB accordingly.


Please check the RabbitMQ documentation which covers extensively the installation of RabbitMQ server and the setup of a RabbitMQ cluster. Also, check out the web management plugin that can be useful for managing and monitoring RabbitMQ.

For a basic installation of RabbitMQ on two nodes (node1 and node2) you can do the following:

On both nodes, install rabbitmq-server and create a Synnefo user:

$ apt-get install rabbitmq-server
$ rabbitmqctl add_user synnefo "example_pass"
$ rabbitmqctl set_permissions synnefo  ".*" ".*" ".*"

Also guarantee that both nodes share the same cookie, by running:

$ scp node1:/var/lib/rabbitmq/.erlang.cookie node2:/var/lib/rabbitmq/.erlang.cookie

and restart the nodes:

$ /etc/init.d/rabbitmq-server restart

To setup the RabbitMQ cluster run:

root@node2: rabbitmqctl stop_app
root@node2: rabbitmqctl reset
root@node2: rabbitmqctl cluster rabbit@node1 rabbit@node2
root@node2: rabbitmqctl start_app

You can verify that the cluster is set up correctly by running:

root@node2: rabbitmqctl cluster_status


Logging in Synnefo is using Python’s logging module. The module is configured using dictionary configuration, whose format is described here:

The logging configuration dictionary is defined in /etc/synnefo/10-snf-webproject-logging.conf

The administrator can have logging control by modifying the LOGGING_SETUP dictionary, and defining subloggers with different handlers and log levels.

By default snf-manage will log any command that is being executed along with its output under the directory LOG_DIR/commands. The LOG_DIR directory can be changed from the 00-snf-common-admins.conf configuration file and the whole snf-manage logging mechanism can be disabled by changing the LOGGER_EXCLUDE_COMMANDS setting to ”.*”.

Scaling up to multiple nodes

Here we will describe how should a large scale Synnefo deployment look like. Make sure you are familiar with Synnefo and Ganeti before proceeding with this section. This means you should at least have already set up successfully a working Synnefo deployment as described in the Admin’s Installation Guide (Debian/CentOS) and also read the Administrator’s Guide until this section.

Graph of a scale-out Synnefo deployment

Each box in the following graph corresponds to a distinct physical node:


The above graph shows the Synnefo roles of each physical node. These roles are described in the following section.

Physical Node roles

As appears in the previous graph, a scale-out Synnefo deployment consists of multiple physical nodes that have the following roles:

  • WEBSERVER: A web server running in front of gunicorn (e.g.: Apache, nginx)
  • ASTAKOS: The Astakos application (gunicorn)
  • ASTAKOS_DB: The Astakos database (postgresql)
  • PITHOS: The Pithos application (gunicorn)
  • PITHOS_DB: The Pithos database (postgresql)
  • CYCLADES: The Cyclades application (gunicorn)
  • CYCLADES_DB: The Cyclades database (postgresql)
  • MQ: The message queue (RabbitMQ)
  • GANETI_MASTER: The Ganeti master of a Ganeti cluster
  • GANETI_NODE : A VM-capable Ganeti node of a Ganeti cluster

You will probably also have:

  • CMS: The CMS used as a frotend portal for the Synnefo services

  • NS: A nameserver serving all other Synnefo nodes and resolving Synnefo FQDNs

  • CLIENT: A machine that runs the Synnefo clients (e.g.: kamaki, Web UI),

    most of the times, the end user’s local machine

From this point we will also refer to the following groups of roles:


Of course, when deploying Synnefo you can combine multiple of the above roles on a single physical node, but if you are trying to scale out, the above separation gives you significant advantages.

So, in the next section we will take a look on what components you will have to install on each physical node depending on its Synnefo role. We assume the graph’s architecture.

Components for each role

When deploying Synnefo in large scale, you need to install different Synnefo or/and third party components on different physical nodes according to their Synnefo role, as stated in the previous section.


  • Synnefo components: None
  • 3rd party components: Apache
  • Synnefo components: snf-webproject, snf-astakos-app
  • 3rd party components: Django, Gunicorn
  • Synnefo components: None
  • 3rd party components: PostgreSQL
  • Synnefo components: snf-webproject, snf-pithos-app, snf-ui-app
  • 3rd party components: Django, Gunicorn
  • Synnefo components: None
  • 3rd party components: PostgreSQL
  • Synnefo components: snf-webproject, snf-cyclades-app, snf-vncauthproxy
  • 3rd party components: Django Gunicorn
  • Synnefo components: None
  • 3rd party components: PostgreSQL
Role MQ
  • Synnefo components: None
  • 3rd party components: RabbitMQ
  • Synnefo components: snf-cyclades-gtools
  • 3rd party components: Ganeti
  • Synnefo components: snf-cyclades-gtools, snf-network, snf-image, nfdhcpd
  • 3rd party components: Ganeti
Role CMS
  • Synnefo components: snf-webproject, snf-cloudcms
  • 3rd party components: Django, Gunicorn
Role NS
  • Synnefo components: None
  • 3rd party components: BIND
  • Synnefo components: kamaki, snf-image-creator
  • 3rd party components: None

Example scale out installation

In this section we describe an example of a medium scale installation which combines multiple roles on 10 different physical nodes. We also provide a guide to help with such an install.

We assume that we have the following 10 physical nodes with the corresponding roles:

Guide sections:
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Same as Node8
Guide sections:
Same as Node8

All sections: Scale out Guide

Regions, Zones and Clusters


A Region is a single Synnefo installation, with Compute/Network/Image/Volume/Object Store services. A Region is associated with one set of Synnefo DBs (Astakos DB, Pithos DB and Cyclades DB). Every Region has a distinct set of API endpoints, e.g., Two Regions are most times located geographically far from each other, e.g. “Europe”, “US-East”. A Region comprises multiple Zones.


A Zone is a set of Ganeti clusters, in a potentially geographically distinct location, e.g. “Athens”, “Rome”. All clusters have access to the same physical networks, and are considered a single failure domain, e.g., they access the network over the same router. A Zone comprises muliple Ganeti clusters.

Ganeti cluster

A Ganeti cluster is a set of Ganeti nodes (physical machines). One of the nodes has the role of “Ganeti master”. If this node goes down, another node may undertake the master role. Ganeti nodes run Virtual Machines (VMs). VMs can live migrate inside a Ganeti cluster. A Ganeti cluster comprises multiple physical hardware nodes, most times geographically close to each other.

VM mobility

VMs may move across Regions, Zones, Ganeti clusters and physical nodes. Before we describe how that’s possible, we will describe the different kinds of moving, providing the corresponding terminology:

Live migration

The act of moving a running VM from physical node to physical node without any impact on its operation. The VM continues to run on its new physical location, completely unaffected, and without any service downtime or dropped connections. Live migration typically requires shared storage and networking between the source and destination nodes.

Live migration is issued by the administrator in the background and is transparent to the VM user.


The act of moving a VM from physical node to physical node by stopping it first on the source node, then re-starting it on the destination node. There is short service downtime, during the time the VM boots up, and client connections are dropped.

Failover is issued by the administrator in the background and the VM user will experience a reboot.

Snapshot Failover

The act of moving a VM from physical node to physical node via a point-in-time snapshot. That is, stopping a VM on the source node, taking a snapshot, then creating a new VM from that snapshot.

Snapshot failover is issued by the VM user and not the administrator.

Disaster Recovery

In Synnefo terminology, Disaster Recovery is the process of sustaining a disaster in one datacenter, and ensuring business continuity by performing live migration or failover of running/existing VMs, or respawning VMs from previously made snapshots. Based on the method used, this can work inside a single Ganeti cluster, across Ganeti clusters in the same Zone, or across Zones.


Live migration is only supported inside a single Ganeti cluster. Ganeti supports live migration between nodes in the same cluster with or without shared storage. Live migration is done at the Ganeti level and is transparent to Synnefo.

Failover is supported inside a Ganeti cluster, across Ganeti clusters and across Zones. Ganeti supports failover inside a Ganeti cluster with or without shared storage, which poses minimum downtime for the VM. Failover inside the same Ganeti cluster is done at the Ganeti level and is transparent to Synnefo.

Ganeti also provides tools for failing over VMs across different Ganeti clusters, meaning that one can use them to failover VMs across Ganeti clusters of the same Zone or across Ganeti clusters of different Zones, thus moving across Zones. Failing over across different Ganeti clusters requires copying of data, resulting in longer downtimes, depending on the geographical distance and network between them. Failover across Ganeti clusters, either in the same or different Zones, is not transparent to Synnefo and requires manual import of intances at Synnefo level too, by the administrator.

Snapshot failover supports moving VMs across all domains. It is issued by the VM user and is done at the Synnefo level without the need of running anything at the Ganeti level or by the administrator.

In the future Synnefo will also support moving VMs across different Regions.

Changelog, NEWS

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