Configuration management on OpenShift, Kubernetes and Docker

When deploying Infinispan on Docker based Cloud environments, the most critical thing is how to manage configuration. In this blog post we'll explore some of the options.

Extending our Docker image

Creating your own Docker image based on jboss/infinispan-server is quite simple. At first you need to prepare a configuration XML file, which is shipped with Infinispan release. Go to Infinispan download section and grap a server release corresponding to a chosen Docker image tag.  After unpacking it, grab the configuration (I use cloud.xml as a template) and introduce all necessary changes. 

Finally, build your image:

Now, that was quick! Wasn't it?

Using ConfigMaps with OpenShift

If you're using OpenShift, there's a sophisticated tool called ConfigMap. A ConfigMap can store a configuration file (or a configuration directory) and mount it somewhere in the Pod.

Use the command below to create a ConfigMap based on a configuration file:

Now create Infinispan application based on the configuration below (you can use 'oc create -f <file.yaml>' for this):

• (lines 50 - 52) - ConfigMap volume declaration
• (lines 45 - 47) - Mounting configuration into /opt/jboss/infinispan-server/standalone/configuration/custom
• (line 22) - bootstrapping the Infinispan with custom configuration (note there is no xml extension there)

Using ConfigMaps with Kubernetes

Kubernetes ConfigMaps work exactly the same way as in OpenShift.

The command below creates a ConfigMap:

The second step is to create a Deployment with ConfigMap:

Conclusion

If you're using any Docker orchestration tool - have a look at provided tools. OpenShift and Kubernetes ConfigMaps are really great for this.

However if you need a fine grained control - either extend our Docker image (this is the preferred way) or simply fork and modify it.

Happy configuring and scaling!