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Contributing Code or Documentation to Micronaut

Finding Issues to Work on

If you are interested in contributing to Micronaut and are looking for issues to work on, take a look at the issues tagged with help wanted.

JDK Setup

Micronaut currently requires JDK 8

IDE Setup

Micronaut can be imported into IntelliJ IDEA by opening the build.gradle file.

Docker Setup

Micronaut tests currently require docker to be installed.

Running Tests

To run the tests use ./gradlew check.

Geb functional tests are ignored unless you specify the geb environment via system property.

To run with Chrome ./gradlew -Dgeb.env=chrome check.

To run with Firefox ./gradlew -Dgeb.env=firefox check.

Building Documentation

The documentation sources are located at src/main/docs/guide.

To build the documentation run ./gradlew publishGuide or ./gradlew pG then open build/docs/index.html

To also build the javadocs instead run ./gradlew docs.

Building the CLI

  • Clone Micronaut Profiles
  • Install micronaut-profiles to Maven Local micronaut-profiles$ ./gradlew clean publishToMavenLocal
  • micronaut-core$ ./gradlew cli:fatJar
  • micronaut-core$ cd cli/build/bin
  • micronaut-core/cli/build/bin$ ./mn

Working on the code base

If you are working with the IntelliJ IDEA development environment, you can import the project using the Intellij Gradle Tooling ( "File / Import Project" and select the "settings.gradle" file).

To get a local development version of Micronaut working, first run the cliZip task.

./gradlew cliZip

Then install SDKman, which is the quickest way to set up a development environment.

Once you have SDKman installed, point SDKman to your local development version of Micronaut.

sdk install micronaut dev /path/to/checkout/cli/build
sdk use micronaut dev

Now the "mn" command will be using your development version!

The most important command you will have to run before sending your changes is the check command.

./gradlew check

For a successful contribution, all tests should be green!

Creating a pull request

Once you are satisfied with your changes:

  • Commit your changes in your local branch
  • Push your changes to your remote branch on GitHub
  • Send us a pull request


We want to keep the code clean, following good practices about organization, javadoc and style as much as possible.

Micronaut uses Checkstyle to make sure that all the code follows those standards. The configuration file is defined in config/checkstyle/checkstyle.xml and to execute the Checkstyle you need to run:

./gradlew <module-name>:checkstyleMain

Before start contributing with new code it is recommended to install IntelliJ CheckStyle-IDEA plugin and configure it to use Micronaut's checkstyle configuration file.

IntelliJ will mark in red the issues Checkstyle finds. For example:

In this case, to fix the issues, we need to:

  • Add one empty line before package in line 16
  • Add the Javadoc for the constructor in line 27
  • Add an space after if in line 34

The plugin also adds a new tab in the bottom to run checkstyle report and see all the errors and warnings. It is recommended to run the report and fixing all the issues before submitting a pull request.

Building on Windows 10

The following prerequisites are needed for building and testing on Windows 10:

  • Docker Desktop version win81 build 29211 or higher is installed and running.
  • OpenSSL binaries are installed, for example ( and on the PATH.