Clustering a log service

Karaf provides a very rich logging service by leveraging Pax logging.

It's possible to change the log level or display the log messages directly in the Karaf shell console using specific commands: log:set, log:get, and log:display.

Cellar will provide the cellar-log optional feature. The installation of this feature will add a new log appender. This appender will store the log messages in a cluster map node/message.

Thanks to this cluster map, from any node we will be able to see log messages on other nodes by issuing the following command:

karaf@root> cluster:log-display
nodeA …
nodeA …
nodeB …
nodeA …

For a specific node, run the following command:

karaf@root> cluster:log-display nodeA
nodeA …
nodeA …

The purpose is to provide a cluster form of the log:* commands.

For instance, it is possible to change the log levels of all nodes in the cluster with the following command:

karaf@root> cluster:log-set DEBUG

For a...