6.3. Profile Versions

Every profile has at least one version. When assigning a profile to a container, you actually assign both the profile and the version. The fabric-agent, will choose the defined version and retrieve all the information provided by the specific version of the profile.

Any change to a profile takes immediate effect. This means that any container using a profile that was just modified will pick up the change immediately. It is recommended that you create a new version of a profile whenever you need to make changes. You can then upgrade containers to use the new version. This enables you to perform atomic updates, test updates on specific containers, and possibly roll back to the previous version, if you encounter any problems.

You can create a new version using the fabric:version-create command (analogous to creating a new branch in the underlying Git repository). The default version is 1.0. To create version 1.1, enter the following command:

fabric:version-create 1.1

After the 1.1 version is created, a new instance of every profile is created for the new version (copied from the previous latest version, which was 1.0). Now you can display or modify the 1.1 version of each profile. For example, enter the following command to display the details of the feature-camel profile:

fabric:profile-display --version 1.1 feature-camel

Initially, the output is identical to the 1.0 version of the profile, because we have not yet modified the new version of the profile. But how do you modify a specific version of a profile? All you need to do is to invoke the fabric:profile-edit command, specifying the version right after the profile argument. For example, to add the camel-jclouds feature to version 1.1 of the feature-camel profile, enter the following command:

fabric:profile-edit --feature camel-jclouds feature-camel 1.1

Fabric provides commands for upgrading (incrementing the effective version) and rolling back (decrementing the effective version) the profiles assigned to a container. For example, to upgrade the mycontainer container to the 1.1 version, invoke the fabric:container-upgrade command as follows:

fabric:container-upgrade 1.1 mycontainer

The preceding command makes mycontainer to use version 1.1 of all the profiles currently assigned to it.

If for any reason you want to roll back to the previous version, you can invoke the fabric:container-rollback command, as follows:

fabric:container-rollback 1.0 mycontainer

It is strongly recommended that you test any profile changes on a single container, before applying the changes to the whole cluster. Applying an upgrade to all containers can be achieved by specifying the --all option, as follows:

fabric:container-upgrade --all 1.1 mycontainer