Quarkus - Deploying on OpenShift

This guide covers generating and deploying OpenShift resources based on sane default and user supplied configuration.

Prerequisites

To complete this guide, you need:

  • roughly 5 minutes

  • an IDE

  • JDK 1.8+ installed with JAVA_HOME configured appropriately

  • Apache Maven 3.6.2+

  • access to an OpenShift cluster (Minishift is a viable option)

Creating the Maven project

First, we need a new project that contains the OpenShift extension. This can be done using the following command:

mvn io.quarkus:quarkus-maven-plugin:1.8.1.Final:create \
    -DprojectGroupId=org.acme \
    -DprojectArtifactId=openshift-quickstart \
    -DclassName="org.acme.rest.GreetingResource" \
    -Dpath="/greeting" \
    -Dextensions="openshift"

cd openshift-quickstart

OpenShift

Quarkus offers the ability to automatically generate OpenShift resources based on sane default and user supplied configuration. The OpenShift extension is actually a wrapper extension that brings together the kubernetes and container-image-s2i extensions with sensible defaults so that it’s easier for the user to get started with Quarkus on OpenShift.

When we added the OpenShift extension to the command line invocation above, the following dependency was added to the pom.xml

    <dependency>
      <groupId>io.quarkus</groupId>
      <artifactId>quarkus-openshift</artifactId>
    </dependency>

By adding this dependency, we now have the ability to configure the OpenShift resource generation and application using the usual application.properties approach that Quarkus provides. The configuration items that are available can be found in: io.quarkus.kubernetes.deployment.OpenShiftConfig class. Furthermore, the items provided by io.quarkus.deployment.ApplicationConfig affect the OpenShift resources.

Building

Building is handled by the container-image-s2i extension. To trigger a build:

./mvnw clean package -Dquarkus.container-image.build=true

The build that will be performed is an s2i binary build. The input of the build is the jar that has been built locally and the output of the build is an ImageStream that is configured to automatically trigger a deployment.

Non S2i Builds

Out of the box the openshift extension is configured to use container-image-s2i. However, it’s still possible to use other container image extensions like:

When a non-s2i container image extension is used, an ImageStream is created that is pointing to an external dockerImageRepository. The image is built and pushed to the registry and the ImageStream populates the tags that are available in the dockerImageRepository.

To select which extension will be used for building the image:

quarkus.container-image.builder=docker

or

quarkus.container-image.builder=jib

Deploying

To trigger a deployment:

./mvnw clean package -Dquarkus.kubernetes.deploy=true

The command above will trigger a container image build and will apply the generated OpenShift resources, right after. The generated resources are using OpenShift’s DeploymentConfig that is configured to automatically trigger a redeployment when a change in the ImageStream is noticed. In other words, any container image build after the initial deployment will automatically trigger redeployment, without the need to delete, update or re-apply the generated resources.

Customizing

All available customization options are available in the OpenShift configuration options.

Some examples are provided in the sections below:

Exposing Routes

To expose a Route for the Quarkus application:

quarkus.openshift.expose=true

Tip: You don’t necessarily need to add this property in the application.properties. You can pass it as a command line argument:

./mvnw clean package -Dquarkus.openshift.expose=true

The same applies to all properties listed below.

Labels

To add a label in the generated resources:

quarkus.openshift.labels.foo=bar

Annotations

To add an annotation in the generated resources:

quarkus.openshift.annotations.foo=bar

Environment variables

To add an annotation in the generated resources:

quarkus.openshift.env-vars.my-env-var.value=foobar

The command above will add MY_ENV_VAR=foobar as an environment variable. Please note that the key my-env-var will be converted to uppercase and dashes will be replaced by underscores resulting in MY_ENV_VAR.

You may also noticed that in contrast to labels, and annotations for environment variables you don’t just use a key=value approach. That is because for environment variables there are additional options rather than just value.

Environment variables from Secret

To add all key value pairs of a Secret as environment variables:

quarkus.openshift.env-vars.my-env-var.secret=my-secret
Environment variables from ConfigMap

To add all key value pairs of a ConfigMap as environment variables:

quarkus.openshift.env-vars.my-env-var.configmap=my-secret

Mounting volumes

The OpenShift extension allows the user to configure both volumes and mounts for the application.

Any volume can be mounted with a simple configuration:

quarkus.openshift.mounts.my-volume.path=/where/to/mount

This will add a mount to my pod for volume my-volume to path /where/to/mount

The volumes themselves can be configured as shown in the sections below:

Secret volumes
quarkus.openshift.secret-volumes.my-volume.secret-name=my-secret
ConfigMap volumes
quarkus.openshift.config-map-volumes.my-volume.config-map-name=my-secret

Knative - OpenShift Serverless

OpenShift also provides the ability to use Knative via the OpenShift Serverless functionality.

The first order of business is to instruct Quarkus to generate Knative resources by setting:

quarkus.kubernetes.deployment-target=knative

In order to leverage OpenShift S2I to build the container image on the cluster and use the resulting container image for the Knative application, we need to set a couple of configuration properties:

# set the Kubernetes namespace which will be used to run the application
quarkus.container-image.group=geoand
# set the container image registry - this is the standard URL used to refer to the internal OpenShift registry
quarkus.container-image.registry=image-registry.openshift-image-registry.svc:5000

The application can then be deployed to OpenShift Serverless by enabling the standard quarkus.kubernetes.deploy=true property.