Friday, 28 October 2016

Infinispan Docker image: custom configuration

In the previous post we introduced the improved Docker image for Infinispan and showed how to run it with different parameters in order to create standalone, clustered and domain mode servers.

This post will show how to address more advanced configuration changes than swapping the JGroups stack, covering cases like creating extra caches or using a pre-existent configuration file.


Runtime configuration changes

Since the Infinispan server is based on Wildfly, it also supports the Command Line Interface (CLI) to change configurations at runtime.

Let's consider an example of a custom indexed cache with Infinispan storage. In order to configure it, we need 4 caches, one cache to hold our data, called testCache and other three caches to hold the indexes:  LuceneIndexesMetadata, LuceneIndexesData and LuceneIndexesLocking.

This is normally achieved by adding this piece of configuration to the server xml:

This is equivalent to the following script:

To apply it to the server, save the script to a file, and run:

where CONTAINER is the id of the running container.

Everything that is applied using the CLI is automatically persisted in the server, and to check what the script produced, use the command to dump the config to a local file called config.xml.

Check the file config.xml: it should contain all four caches created via the CLI.


 Using an existent configuration file

Most of the time changing configuration at runtime is sufficient, but it may be desirable to run the server with an existent xml, or change configurations that cannot be applied without a restart. For those cases, the easier option is to mount a volume in the Docker container and start the container with the provided configuration.

This can be achieved with Docker's volume support. Consider an xml file called customConfig.xml located on a local folder /home/user/config. The following command:

will create a volume inside the container at the /opt/jboss/infinispan-server/standalone/configuration/extra/ directory, with the contents of the local folder /home/user/config.

The container is then launched with the entrypoint extra/customConfig, which means it will use a configuration named customConfig located under the extra folder relative to where the configurations are usually located at /opt/jboss/infinispan-server/standalone/configuration.



And that's all about custom configuration using the Infinispan Docker image.

Stay tuned for the next post where we'll dive into multi-host clusters with the Infinispan Docker image.

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