Until now, we have used Cellar as a global cluster. This means that all the nodes will have the same functions and roles in the cluster. However, when using a pool or farm of Karaf instances in a real live system, we may want to dedicate a subset of the instances for the given functions/roles. This is the role of the Cellar cluster groups.
For instance, we have a farm of 20 nodes in our Cellar cluster.
We may want to deploy the following:
A camel route can be described and packaged as a
Karaf FeaturesXML file. We want to deploy this route only on 10 nodes of the cluster (not on all the nodes).A CXF web service (described and deployed as another
Karaf FeaturesXML file) on the other 10 nodes.
In Cellar, we can create different cluster groups and define a node as a member of one or more cluster groups.