Multi Module Maven Release Plugin

Plugin setup

There are some plugins that should only be executed during releases, like the Nexus staging plugin, so you may wish to enable a profile during a release which has those plugins. The following will enable the release profile during a release.

<build>
    <plugins>
        <plugin>
            <groupId>com.github.danielflower.mavenplugins</groupId>
            <artifactId>multi-module-maven-release-plugin</artifactId>
            <version>3.7.8</version>
            <configuration>
                <releaseProfiles>
                    <releaseProfile>release</releaseProfile>
                </releaseProfiles>
            </configuration>
        </plugin>
    </plugins>
</build>

The release profile can just have the maven-gpg-plugin (used to sign all the generated artifacts) and the nexus-staging-maven-plugin. Note that both plugins will use secrets that are saved in ~/.m2/settings.xml which is created in the release.yaml file described below.

<profiles>
    <profile>
        <id>release</id>
        <build>
            <plugins>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-gpg-plugin</artifactId>
                    <configuration>
                        <gpgArguments>
                            <arg>--pinentry-mode</arg>
                            <arg>loopback</arg>
                        </gpgArguments>
                    </configuration>
                    <executions>
                        <execution>
                            <id>sign-artifacts</id>
                            <phase>verify</phase>
                            <goals>
                                <goal>sign</goal>
                            </goals>
                        </execution>
                    </executions>
                </plugin>
                <plugin>
                    <groupId>org.sonatype.plugins</groupId>
                    <artifactId>nexus-staging-maven-plugin</artifactId>
                    <extensions>true</extensions>
                    <configuration>
                        <serverId>ossrh</serverId>
                        <nexusUrl>https://oss.sonatype.org/</nexusUrl>
                        <autoReleaseAfterClose>true</autoReleaseAfterClose>
                    </configuration>
                </plugin>
            </plugins>
        </build>
    </profile>
</profiles>

You'll also need to enable the maven-javadoc-plugin and maven-sources-plugin as per OSSRH requirements. You can put these in your release profile or normal build section.

Secrets management

Add the following secrets to your repository or organisation:

• OSSRH_USERNAME - the username you use to log in to OSS Nexus
• OSSRH_TOKEN - the password for your OSSRH user
• OSSRH_GPG_SECRET_KEY - your GPG key as described here.
• OSSRH_GPG_SECRET_KEY_PASSWORD - the password for your GPG key

Set your SCM plugin URLs to use HTTPS

Make sure HTTPS is used in your scm section as SSH URLs will not work during the release from GitHub Actions. For example:

<scm>
    <url>https://github.com/3redronin/mu-acme</url>
    <connection>scm:git:https://github.com/3redronin/mu-acme.git</connection>
</scm>

Create a release workflow

Create a file in your git repository at .github/workflows/release.yaml which has the following contents which will first test and verify your package using Java 11, and then release to OSSRH:

name: Publish to Maven Central Repository
on: workflow_dispatch

jobs:
  publish:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
        with:
          fetch-depth: 0
      - name: Install gpg secret key
        run: cat <(echo -e "${{ secrets.OSSRH_GPG_SECRET_KEY }}") | gpg --batch --import
      - name: Set up Maven Central Repository
        uses: actions/setup-java@v3
        with:
          java-version: '11'
          distribution: 'temurin'
      - name: Set up maven settings
        uses: s4u/maven-settings-action@v2.8.0
        with:
          servers: |
            [{
              "id": "ossrh",
              "username": "${{ secrets.OSSRH_USERNAME }}",
              "password": "${{ secrets.OSSRH_TOKEN }}"
            },
            {
              "id": "gpg.passphrase",
              "passphrase": "${{ secrets.OSSRH_GPG_SECRET_KEY_PASSWORD }}",
              "configuration": {}
            }]
      - name: Verify package
        run: mvn --batch-mode verify
      - name: Release package
        run: mvn --batch-mode -DskipTests=true releaser:release

Build triggers, java versions and build steps can be customised for your own requirements. The important bits to make sure remain are the fetch-depth: 0 for checkout (so the plugin can look at the git tags in your repo), the GPG secret key installation and the maven-settings action.

With these settings committed and pushed to GitHub, you should see a Publish to Maven Central job in the Actions section which lets you manually run the release.