This tutorial will teach you how to run the latest version of WildFly on Openshift. We will then look at advanced options such as overriding the default server settings (WildFly 26 update). Finally, we will learn how to create a custom WildFly distribution using Galleon layers.

Setting up WildFly Image Streams

Openshift uses Image Streams to reference a Docker image. An image stream comprises one or more Docker images identified by tags. It presents a single virtual view of related images, similar to a Docker image repository, and may contain images from any of the following:

$ oc get is -n openshift

$ oc login -u system:admin

$ oc create -f https://raw.githubusercontent.com/wildfly/wildfly-s2i/wf-26.0/imagestreams/wildfly-centos7.json

$ oc login 
Authentication required for https://192.168.1.194:8443 (openshift) 
Username: developer 
Password: developer

$ oc new-app wildfly:26~https://github.com/fmarchioni/ocpdemos --context-dir=wildfly-basic --name=wildfly-basic

$ oc expose service wildfly-basic

Finally, checkout the Route which has been created:

$ oc get route
NAME            HOST/PORT                                        PATH   SERVICES        PORT       
wildfly-basic   wildfly-basic-demo.apps.fmarchio-qe.rh-ocs.com          wildfly-basic   8080-tcp

Open the browser at the Route Host address, and here is your example application on Openshift:

How to override WildFly settings

In WildFly 26 there is a nice shortcut to override the configuration settings of the application server. You can inject configuration values through environment variables, using a conversion pattern.

Let’s see it with an example. Supposing you want to set the following attribute:

/subsystem=io/worker=default:write-attribute(name=task-max-threads,value=50)

To set the task-max-threads attribute of the io subsystem, you will set the following environment variable:

SUBSYSTEM_IO_WORKER_DEFAULT__TASK_MAX_THREADS=30

Here’s how the conversion works:

1. Remove the trailing slash
2. Turn the CLI command to uppercase
3. Then, replace non-alphanumeric characters with an underscore (_)
4. Add two underscores (__) to the name of the attribute you are going to set

The transformation is not on by default. You have to set this environment variable to enable it:

WILDFLY_OVERRIDING_ENV_VARS=1

Let’s wrap it up! Here is how you can create the WildFly example application setting the task-max-threads attribute:

oc new-app wildfly:26.0~https://github.com/fmarchioni/ocpdemos --context-dir=wildfly-basic --name=wildfly-basic -e WILDFLY_OVERRIDING_ENV_VARS=1 -e SUBSYSTEM_IO_WORKER_DEFAULT__TASK_MAX_THREADS=30

That’s it! You can rsh into the Pod to verify that the attribute is in the configuration:

<subsystem xmlns="urn:jboss:domain:io:3.0">
    <worker name="default" task-max-threads="50"/>
    <buffer-pool name="default"/>
</subsystem>

It is worth mentioning, that you can also set the Environment variables on the Deployment of your application. That will, by default, trigger a restart of your Pod:

Provisioning WildFly layers on Openshift with Galleon

If you don’t need the full sized WildFly application server, you can provision an Image of it which just contains the layers you need. For example, if you only need to use REST Server API (and their dependencies such as the Web Server), you can create the above example:

oc new-app wildfly:26~https://github.com/fmarchioni/ocpdemos --context-dir=wildfly-basic --name=wildfly-basic --build-env GALLEON_PROVISION_LAYERS=jaxrs-server

You can verify your custom WildFly configuration by logging into the Pod which runs WildFly:

$ oc get pods
NAME                     READY   STATUS      RESTARTS   AGE
wildfly-basic-1-build    0/1     Completed   0          5m22s
wildfly-basic-1-deploy   0/1     Completed   0          2m27s
wildfly-basic-1-gk6z9    1/1     Running     0          2m22s

Now launch a remote shell (rsh) into the Running Pod:

$ oc rsh wildfly-basic-1-gk6z9

sh-4.2$

And have a look at the extensions installed in your WildFly Server (for the sake of brevity, just the top of the configuration is shown):

sh-4.2$ cat /wildfly/standalone/configuration/standalone.xml

<server xmlns="urn:jboss:domain:10.0">
    <extensions>
        <extension module="org.jboss.as.clustering.infinispan"/>
        <extension module="org.jboss.as.connector"/>
        <extension module="org.jboss.as.deployment-scanner"/>
        <extension module="org.jboss.as.ee"/>
        <extension module="org.jboss.as.jaxrs"/>
        <extension module="org.jboss.as.jmx"/>
        <extension module="org.jboss.as.jpa"/>
        <extension module="org.jboss.as.logging"/>
        <extension module="org.jboss.as.naming"/>
        <extension module="org.jboss.as.transactions"/>
        <extension module="org.jboss.as.weld"/>
        <extension module="org.wildfly.extension.bean-validation"/>
        <extension module="org.wildfly.extension.core-management"/>
        <extension module="org.wildfly.extension.elytron"/>
        <extension module="org.wildfly.extension.io"/>
        <extension module="org.wildfly.extension.request-controller"/>
        <extension module="org.wildfly.extension.security.manager"/>
        <extension module="org.wildfly.extension.undertow"/>
    </extensions>

As you can see, just the RESTEasy API, its dependencies and the Core dependencies have been created.

That’s all. If you want to learn further about WildFly on OpenShift, we recommend checking this tutorial_Create custom WildFly container images with S2I toolkit