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Lab: Deploying Java Code on JBoss

Background: Source-to-Image (S2I)

In lab three we learned how to deploy a pre-existing Docker image from a Docker registry. Now we will expand on that a bit by learning how OpenShift builds a Docker images using source code from an existing repository.

Source-to-Image (S2I) is another open source project sponsored by Red Hat. Its goal:

Source-to-image (S2I) is a tool for building reproducible Docker images. S2I
produces ready-to-run images by injecting source code into a Docker image and
assembling a new Docker image which incorporates the builder image and built
source. The result is then ready to use with docker run. S2I supports
incremental builds which re-use previously downloaded dependencies, previously
built artifacts, etc.

OpenShift is S2I-enabled and can use S2I as one of its build mechanisms (in addition to building Docker images from Dockerfiles, and "custom" builds).

OpenShift runs the S2I process inside a special Pod, called a Build Pod, and thus builds are subject to quotas, limits, resource scheduling, and other aspects of OpenShift.

A full discussion of S2I is beyond the scope of this class, but you can find more information about it either in the OpenShift S2I documentation or on GitHub (following the link above). The only key concept you need to remember about S2I is that it’s magic.

Exercise: Creating a WildFly application

The backend service we will be deploying as part of this exercise is called nationalparks. This application is a Java EE-based application that performs 2D geo-spatial queries against a MongoDB database to locate and map all National Parks in the world. That was just a fancy way of saying that we are going to deploy a map of National Parks.

Create Project

The first thing you need to do is create a new project called nationalparks:

$ oc new-project nationalparks{{USER_SUFFIX}}
Now using project "nationalparks{{USER_SUFFIX}}" on server "https://{{ROUTER_ADDRESS}}".

You can add applications to this project with the 'new-app' command. For example, try:

    $ oc new-app centos/ruby-22-centos7~https://github.com/openshift/ruby-hello-world.git

to build a new hello-world application in Ruby.
Using application code on embedded GitLab

OpenShift can work with any accessible Git repository. This could be GitHub, GitLab, or any other server that speaks Git. You can even register webhooks in your Git server to initiate OpenShift builds triggered by any update to the application code!

The repository that we are going to use is already cloned in the internal GitLab repository and located at the following URL:

<< NEEDSFIX >>

Your GitLab credentials are: {{GITLAB_USER}}/{{GITLAB_PASSWORD}}

Later in the lab, we want you to make a code change and then rebuild your application. If you are familiar with Java EE applications, you will notice that there is nothing special about our application - it is a standard, plain-old JEE application.

Combine the code with the Docker image on OpenShift

While the new-app command makes it very easy to get OpenShift to build code from a GitHub/GitLab repository into a Docker image, we can also use the web console to do the same thing. Similar to how we used "Add to project" before with a Docker-formatted image, we can do the same for specifying a source code repository. Since for this lab you have your own GitLab repository let’s use it with OpenShift’s {{JAVA_BUILDER}} S2I image.

In the OpenShift web console, find your nationalparks{{USER_SUFFIX}} project, and then click the "Add to Project" button. You will see a number of runtimes that you can choose from, but you will want to select the one titled {{JAVA_BUILDER_STRING}}. As you might guess, this is going to use an S2I builder image that contains {{JAVA_BUILDER_PROPER}}.

<< NEEDS IMAGE >>

Runtimes

After you click "Add to Project", on the next screen you will need to enter a name and a Git repository URL. For the name, enter openshift3nationalparks, and for the Git repository URL, enter:

http://{{GITLAB_URL_PREFIX}}.{{ROUTER_ADDRESS}}/dev/nationalparks.git
Note
 All of these runtimes shown are made available via Templates, which will be discussed in a later lab.
Runtimes

NOTE: To speed build process, a Sonatype Nexus server is running in the environment that will cache your dependencies as you pull them down. To use it, you need to click on Show advanced routing, build, and deployment options, scroll down to Build Configuration, add an environment variable named MAVEN_MIRROR_URL with value http://nexus.ci:8081/content/groups/public

Runtimes

You can then hit the button labeled "Create". Then click Continue to overview. You will see this in the web console:

Build openshift3nationalparks #1 is running. A new deployment will be created
automatically once the build completes. View Log

Go ahead and click "View Log". This is a new Java-based project that uses Maven as the build and dependency system. For this reason, the initial build will take a few minutes as Maven downloads all of the dependencies needed for the application. You can see all of this happening in real time!

From the command line, you can also see the Builds:

$ oc get builds

You’ll see output like:

NAME                        TYPE      FROM        STATUS     STARTED              DURATION
openshift3nationalparks-1   Source    Git@master  Running    3 minutes ago        1m2s

You can also view the build logs with the following command:

$ oc logs -f builds/openshift3nationalparks-1

After the build has completed and successfully:

  • The S2I process will push the resulting Docker image to the internal OpenShift registry

  • The DeploymentConfiguration (DC) will detect that the image has changed, and this will cause a new deployment to happen.

  • A ReplicationController (RC) will be spawned for this new deployment.

  • The RC will detect no Pods are running and will cause one to be deployed, as our default replica count is just 1.

In the end, when issuing the oc get pods command, you will see that the build Pod has finished (exited) and that an application Pod is in a ready and running state:

NAME                              READY     STATUS      RESTARTS   AGE
openshift3nationalparks-1-build   0/1       Completed   0          4m
openshift3nationalparks-1-7e3ij   1/1       Running     0          2m

If you look again at the web console, you will notice that, when you create the application this way, OpenShift also creates a Route for you. You can see the URL in the web console, or via the command line:

$ oc get routes

Where you should see something like the following:

NAME                      HOST/PORT                                                     PATH  SERVICE                   LABELS ...
openshift3nationalparks   openshift3nationalparks-nationalparks.{{ROUTER_ADDRESS}}          openshift3nationalparks   app=openshift3nationalparks

In the above example, the URL is:

http://openshift3nationalparks-nationalparks.{{ROUTER_ADDRESS}}

Verify your application is working by viewing the URL in a web browser. You should see the following:

MLBParks

Wait a second! Why are the national parks not showing up? Well, that is because we haven’t actually added a database to the application yet. We will do that in the next lab. Congratulations on deploying your first application using S2I on the OpenShift Platform!