Create a GitHub App

Initialize your Quarkus application

A Quarkus GitHub App is a standard Quarkus application.

You can create one including the Quarkus GitHub App extension with the following command:

mvn io.quarkus:quarkus-maven-plugin:2.16.6.Final:create \
    -DplatformVersion=2.16.6.Final \
    -DprojectGroupId=org.acme \
    -DprojectArtifactId=my-github-app \
    -Dextensions="io.quarkiverse.githubapp:quarkus-github-app:1.17.1" \

Maven 3.8.1+ is required for this to work.

Once the project is created, go to the my-github-app directory.

Initialize the configuration

As the configuration is environment-specific and you probably don’t want to commit it in your repository, the best is to create a .env file.

The content of your .env file should be as follows:

QUARKUS_GITHUB_APP_APP_ID=<the numeric app id>
QUARKUS_GITHUB_APP_APP_NAME=<the name of your app>
                  <your private key>                          \

The numeric app id appearing in the App ID field.


The name of your app is the one appearing in the GitHub URL. It is only used to improve usability in dev mode.


The URL you obtained when you created your channel.


The webhook secret you created at the previous step.


The content of the private key you generated and downloaded. Open the key file with a text editor as key viewers usually only show fingerprints.

Don’t forget to add backslashes at the end of the lines of your private key (except the last one). In a property file, that is how a multi-line value is considered one value.

Once you have created your .env, you are all set.

Start dev mode and enjoy

If you are familiar with Quarkus, you already know the dev mode which improves productivity a lot. If you are not, the principle is that you start your application once and code: Quarkus will take care of reloading the application when it receives a request.

Just execute the following command to start Quarkus in dev mode:

./mvnw quarkus:dev

If you have a configuration error, it’s probably because you did something wrong with the .env file. Check the instructions above carefully.

Time to code

From now on, you are done with the setup and you can code your GitHub App. Sky is the limit.

For instance, you can create the following class:

class CreateComment {

	void onOpen(@Issue.Opened GHEventPayload.Issue issuePayload) throws IOException {
		issuePayload.getIssue().comment("Hello from my GitHub App");

From now on, every time you create an issue in your GitHub project, a comment will be added by your GitHub App.

In details:

  • No need for public modifier, your classes and methods can be package protected.

  • We listen to the @Issue.Opened event i.e. this method will be called for each issue opened.

  • A payload of type GHEventPayload.Issue will be injected in our method automatically. This class is provided by the Hub4j GitHub API.

Compiling to a native executable

One of the great benefits of Quarkus is that you can easily build a native executable from your Java applications. Native executables offer faster boot and lower memory footprint.

Your GitHub App is no exception and you can build a native executable using GraalVM with:

./mvnw package -Dnative

For this to work, you will need GraalVM installed. See Building a native executable on the Quarkus website for more information.

Building a native executable takes a while and is both CPU and memory intensive.

You can then start the native executable with:


And more

You are done developing your first Quarkus GitHub App.

Obviously the one we developed is not very useful, but it is a good start and using this framework:

  • You can listen to all the events currently supported by the Hub4j GitHub API.

  • You have the full power of Quarkus with live coding, easy configuration, dependency injection, native executables and more.

  • You can write automated tests that simulate GitHub events and assert the behavior of your application.

  • You have at your disposal the full ecosystem of Quarkus extensions and the broader Java ecosystem.

Our Replay UI will come handy while developing your GitHub App.

You can learn more about all the events you can listen to in our Developer Reference.

When you are done developing your application, please refer to Push to Production.