21 Jan 2011

How to change the ActiveMQ broker configuration when running inside ServiceMix?

Update: This post does not apply to Fuse ESB Enterprise 7.x and higher. It only applies to Apache ServiceMix and Fuse ESB up to versions 4.x.

I mistakenly assumed that I can simply update the embedded ActiveMQ broker configuration at $KARAF_HOME/etc/activemq-broker.xml and restart SMX for these changes to take effect.

That is not the case.

ServiceMix monitors the etc/ folder via an OSGI management agent. It scans the etc/ folder, installs and starts a bundle when it is first placed there. The etc/config.properties file configures this agent:

felix.fileinstall.dir = ${karaf.base}/etc
felix.fileinstall.filter = .*\\.cfg
felix.fileinstall.poll = 1000
felix.fileinstall.noInitialDelay = true

So when ServiceMix starts up the first time the agent will read the activemq-broker.xml file from etc/, wrap it as an OSGI bundle and deploy it into the bundle cache. Changes to etc/activemq-broker.xml thereafter will not cause the bundle to be redeployed automatically, not even after a restart of ServiceMix. This is the actually the same behavior as deploying a bundle using, e.g. osgi:install mvn:… from your local Maven repository. Updating the bundle in your Maven repo does not cause ServiceMix to redeploy it automatically for you (which is certainly good).

So after changing the configuration of etc/activemq-broker.xml, make sure to update the ActiveMQ broker bundle:

karaf@root> list -l | grep activemq-broker.xml
[ 57] [Active ] [Created ] [ ] [60] blueprint:file:etc/activemq-broker.xml
karaf@root>update 57

It will stop the embedded broker, reload the configuration as an OSGI bundle and restart the broker with the new configuration in effect.


Claus Ibsen said...

Jesus this is really not intuitive. I think the Karaf team should find a better solution. This will cause a lot of pain and grief.

Anonymous said...

To be clear, it's not felix fileinstall that loads the XML. Instead it's this servicemix feature:

<feature name="activemq-broker" version="4.3.0">
<feature version="5.4.2">activemq-blueprint</feature>