hello-java

This is a small application that runs Undertow, as an embedded web server, to return a nice greeting.

I created this to use for as a simple test for pipelines, demos and other stuff.

To compile and run

To compile the application and build a fat-jar (jar-with-dependencies):

mvn clean package

Then, to run:

java -jar target/hello-java-1.0.0-SNAPSHOT.jar

To build a Docker image

To build and push an OCI (Docker) image - e.g. to run on Kubernetes - set your registry credentials in environment variables and run jib:build with the image repository that you want to push to:

export REGISTRY_USERNAME=youruser@example.com
export REGISTRY_PASSWORD=registrypassssssswd

mvn compile jib:build -Djib.to.image=quay.io/youruser/yourimage:latest \
    -Djib.to.auth.username=$REGISTRY_USERNAME \
    -Djib.to.auth.password=$REGISTRY_PASSWORD

This uses Google Jib to build the image. It doesn't build an executable JAR, but instead splits the build outputs into image layers (classes, libs, resources, etc.) and sets the container entrypoint to something like:

java -cp /app/resources:/app/classes:/app/libs/* xyz.tomd.demos.hellorestjava.Application

Kubernetes

Helm chart

A Helm chart is included with this application. To deploy the app onto Kubernetes, first install the Helm client and then run:

helm install mydemo hello-java

This will create a Release of this app called mydemo:

$ kubectl get pod -w
NAME                                READY   STATUS    RESTARTS   AGE
mydemo-hello-java-6fb5d686c-67lqw   0/1     Running   0          14s

CI

Jenkins on OpenShift

This application includes a sample pipeline for Jenkins, intended to be used with Jenkins on OpenShift.

To set it up:

1. Fork this repo.

2. Deploy Jenkins from the OpenShift application catalogue.

3. Create a Pipeline job, choose Pipeline source from SCM and configure the URL to this repo (or your own fork, if you've forked this repo.)

4. Edit the openshift-build.yml file and set the Build target to point to the registry where you want to push the finished image, e.g.:

   output:
       to:
           kind: DockerImage
           name: docker.io/YOURUSERNAME/hello-java:latest
   

5. Create a BuildConfig object, in the same namespace as Jenkins:

   oc apply -f openshift-build.yml
   

6. Add a secret to authenticate to your external registry and link it to the builder service account:

   oc create secret docker-registry my-secret \ 
       --docker-server=docker.io \
       --docker-username=YOURUSERNAME \ 
       --docker-password=xxx \ 
   
   oc secrets link builder my-secret --for=mount
   

7. Run the pipeline in Jenkins.

Concourse CI

This application includes a sample pipeline for Concourse CI that builds a Docker image with Jib and pushes it to an external registry.

When finished, it looks like this:

Set up the pipeline

Set up concourse credentials, and log in:

export CONCOURSE_EXTERNAL_URL=https://concourse.eggworld.example.com
export CONCOURSE_USER=username
export CONCOURSE_PASSWORD=password

fly -t tutorial login -k -c ${CONCOURSE_EXTERNAL_URL} \
    -u ${CONCOURSE_USER} -p ${CONCOURSE_PASSWORD}

Now configure your username and password for the container registry so that Jib can push the Docker image when it's built (I'm using Quay.io):

export REGISTRY_USERNAME=your-quay-username
export REGISTRY_PASSWORD=your-quay-password

Next, create the pipeline, setting your registry credentials as variables (-v):

fly -t tutorial set-pipeline -c ci/concourse/pipeline.yml -p hello-java \
    -v registry-username=${REGISTRY_USERNAME} \
    -v registry-password=${REGISTRY_PASSWORD} \
    -v image-name=yourregistry.example.com/youruser/hello-java

NB: This demo pipeline uses simple variable interpolation. This means that these sensitive credentials are set explicitly in the pipeline when you run fly set-pipeline. For a production setup, you should fetch credentials from something like Vault instead.

Run the pipeline

Now unpause the pipeline - it will turn grey:

fly -t tutorial unpause-pipeline -p hello-java

Finally run the job in the web console, make a Git commit, or run it from the command line and follow the logs:

fly -t tutorial trigger-job -j hello-java/unit --watch

Optionally deploy the application to OpenShift

You can deploy the application to OpenShift using the template provided in openshift-template.yml. You'll need to configure the template with the full image spec where OpenShift can find the image:

oc new-project my-project

oc process -f openshift-template.yml \
    -p IMAGE=yourregistry.example.com/youruser/hello-java \
    | oc apply -f -

Now whenever the pipeline runs and pushes a new image, the application will be updated in OpenShift (when OpenShift notices the updated tag, which can take around 15 minutes).