{"id":107904,"date":"2020-01-23T08:00:10","date_gmt":"2020-01-23T08:00:10","guid":{"rendered":"https:\/\/developers.redhat.com\/blog\/?p=675247"},"modified":"2020-01-23T08:00:10","modified_gmt":"2020-01-23T08:00:10","slug":"using-kubernetes-configmaps-to-define-your-quarkus-applications-properties","status":"publish","type":"post","link":"https:\/\/sickgaming.net\/blog\/2020\/01\/23\/using-kubernetes-configmaps-to-define-your-quarkus-applications-properties\/","title":{"rendered":"Using Kubernetes ConfigMaps to define your Quarkus application\u2019s properties"},"content":{"rendered":"

So, you wrote your Quarkus application, and now you want to deploy it to a Kubernetes cluster. Good news: Deploying a Quarkus application to a Kubernetes cluster is easy. Before you do this, though, you need to straighten out your application’s properties. After all, your app probably has to connect with a database, call other services, and so on. These settings are already defined in your application.properties<\/code> file, but the values match the ones for your local environment and won’t work once deployed onto your cluster.<\/p>\n

So, how do you easily solve this problem? Let’s walk through an example.<\/p>\n

<\/span><\/p>\n

Create the example Quarkus application<\/h2>\n

Instead of using a complex example, let’s take a simple use case that explains the concept well. Start by creating a new Quarkus app:<\/p>\n

$ mvn io.quarkus:quarkus-maven-plugin:1.1.1.Final:create<\/pre>\n
You can keep all of the default values while creating the new application. In this example, the application is named hello-app<\/code>. Now, open the HelloResource.java<\/code> file and refactor it to look like this:<\/p>\n
@Path(\"\/hello\") public class HelloResource { @ConfigProperty(name = \"greeting.message\") String message; @GET @Produces(MediaType.TEXT_PLAIN) public String hello() { return \"hello \" + message; } } <\/pre>\n
In your application.properties<\/code> file, now add greeting.message=localhost<\/code>. The @ConfigProperty<\/code> annotation is not in the scope of this article, but here we can see how easy it is to inject properties inside our code using this\u00a0annotation.<\/p>\n
Now, let’s start our application to see if it works as expected: <\/code><\/p>\n
$ mvn compile quarkus:dev<\/pre>\n
Browse to http:\/\/localhost:8080\/hello<\/code>, which should output hello localhost<\/code>. That’s it for the Quarkus app. It’s ready to go.<\/p>\n
Deploy the application to the Kubernetes cluster<\/h2>\n
The idea here is to deploy this application to our Kubernetes cluster and replace the value of our greeting<\/code> property with one that will work on the cluster. It is important to know here that all of the properties from application.properties<\/code> are exposed, and thus can be overridden with environment variables. The convention is to convert the name of the property to uppercase and replace every dot (.<\/code>) with an underscore (_<\/code>). So, for instance, our greeting.message<\/code> will become GREETING_MESSAGE<\/code>.<\/p>\n
At this point, we are almost ready to deploy our app to Kubernetes, but we need to do three more things:<\/p>\n
    \n
  1. Create a Docker image of your application and push it to a repository that your cluster can access.<\/li>\n
  2. Define a ConfgMap resource.<\/li>\n
  3. Generate the Kubernetes resources for our application.<\/li>\n<\/ol>\n
    To create the Docker image, simply execute this command:<\/p>\n
    $ docker build -f src\/main\/docker\/Dockerfile.jvm -t quarkus\/hello-app .<\/pre>\n
    Be sure to set the right Docker username and to also push to an image registry, like docker-hub<\/code> or quay<\/code>. If you are not able to push an image, you can use sebi2706\/hello-app:latest<\/code>.<\/p>\n
    Next, create the file config-hello.yml<\/code>:<\/p>\n
    apiVersion: v1 data: greeting: \"Kubernetes\" kind: ConfigMap metadata: name: hello-config <\/pre>\n
    Make sure that you are connected to a cluster and apply this file:<\/p>\n
    $ kubectl apply -f config-hello.yml<\/pre>\n
    Quarkus comes with a useful extension, quarkus-kubernetes<\/code>, that generates the Kubernetes resources for you. You can even tweak the generated resources by providing extra properties\u2014for more details, check out this guide<\/a>.<\/p>\n
    After installing the extension, add these properties to our application.properties<\/code> file so it generates extra configuration arguments for our containers specification:<\/p>\n
    kubernetes.group=yourDockerUsername kubernetes.env-vars[0].name=GREETING_MESSAGE kubernetes.env-vars[0].value=greeting kubernetes.env-vars[0].configmap=hello-config<\/pre>\n
    Run mvn package<\/code> and view the generated resources in target\/kubernetes<\/code>. The interesting part is in spec.containers.env<\/code>:<\/p>\n
    - name: \"GREETING_MESSAGE\" \u00a0 valueFrom: \u00a0 configMapKeyRef: \u00a0\u00a0\u00a0 key: \"greeting\" \u00a0\u00a0 name: \"hello-config\"<\/pre>\n
    Here, we see how to pass an environment variable to our container with a value coming from a ConfigMap. Now, simply apply the resources:<\/p>\n
    $ kubectl apply -f target\/kubernetes\/kubernetes.yml<\/pre>\n
    Expose your service:<\/p>\n
    kubectl expose deployment hello --type=NodePort<\/code><\/pre>\n
    Then, browse to the public URL or do a curl. For instance, with Minikube:<\/p>\n
    $ curl $(minikube service hello-app --url)\/hello<\/code><\/pre>\n
    This command should output: hello Kubernetes<\/code>.<\/p>\n
    Conclusion<\/h2>\n
    Now you know how to use a ConfigMap in combination with environment variables and your Quarkus’s application.properties<\/code>. As we said in the introduction, this technique is particularly useful when defining a DB connection’s URL (like QUARKUS_DATASOURCE_URL<\/code>) or when using the quarkus-rest-client<\/code> (ORG_SEBI_OTHERSERVICE_MP_REST_URL<\/code>).<\/p>\n
    <\/a><\/a><\/a><\/a><\/a><\/a><\/a>\"Share\"<\/a><\/p>\n
    The post Using Kubernetes ConfigMaps to define your Quarkus application’s properties<\/a> appeared first on Red Hat Developer<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"
    So, you wrote your Quarkus application, and now you want to deploy it to a Kubernetes cluster. Good news: Deploying a Quarkus application to a Kubernetes cluster is easy. Before you do this, though, you need to straighten out your application’s properties. After all, your app probably has to connect with a database, call other […]<\/p>\n","protected":false},"author":2,"featured_media":107905,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[858,3],"tags":[886,887,888,444,539,859,513,872],"class_list":["post-107904","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-java-tutorials","category-tutorials","tag-cluster","tag-configmap","tag-deploy-app","tag-devops","tag-docker","tag-java","tag-kubernetes","tag-quarkus"],"_links":{"self":[{"href":"https:\/\/sickgaming.net\/blog\/wp-json\/wp\/v2\/posts\/107904","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/sickgaming.net\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/sickgaming.net\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/sickgaming.net\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/sickgaming.net\/blog\/wp-json\/wp\/v2\/comments?post=107904"}],"version-history":[{"count":0,"href":"https:\/\/sickgaming.net\/blog\/wp-json\/wp\/v2\/posts\/107904\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/sickgaming.net\/blog\/wp-json\/wp\/v2\/media\/107905"}],"wp:attachment":[{"href":"https:\/\/sickgaming.net\/blog\/wp-json\/wp\/v2\/media?parent=107904"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/sickgaming.net\/blog\/wp-json\/wp\/v2\/categories?post=107904"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/sickgaming.net\/blog\/wp-json\/wp\/v2\/tags?post=107904"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}