Suppressing GPG signing for Maven-based continuous integration builds (Travis CI)

Disable GPG signing by adding the following line to your .travis.yml file:

install: mvn install -DskipTests -Dgpg.skip

Example: https://github.com/stefanbirkner/system-rules/blob/master/.travis.yml

You need to create a profile & make sure you run that only when you do the release build.

Remove the current plugin, and add it in a profile like this:

<profiles>
    <profile>
        <id>release-sign-artifacts</id>
        <activation>
            <property>
                <name>performRelease</name>
                <value>true</value>
            </property>
        </activation>
        <build>
            <plugins>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-gpg-plugin</artifactId>
                    <version>1.4</version>
                    <executions>
                        <execution>
                            <id>sign-artifacts</id>
                            <phase>verify</phase>
                            <goals>
                                <goal>sign</goal>
                            </goals>
                        </execution>
                    </executions>
                </plugin>
            </plugins>
        </build>
    </profile>
</profiles>

And then when you actually need to do a release, add the property to your mvn command:

mvn -DperformRelease=true ...

I found a slightly simpler way to do it with the profile as described above. Instead of using a new property value, you can use the gpg.passphrase property which will need to be provided anyway when doing signing. The modified property section is as follows:

<activation>
    <property>
        <name>gpg.passphrase</name>
    </property>
</activation>

Notice, that no value is required since you want this profile to activate if any value is set for that property.

The corresponding command line then looks like this:

mvn <command> -Dgpg.passphrase=myverysupersecretpassphrase

You can test this out by running it the following two ways:

mvn install

No signed artifacts get generated, and:

mvn install -Dgpg.passphrase=myverysupersecretpassphrase

Signed artifacts get created.

To do the actual signed release of the artifacts do the following:

mvn release:perform -Darguments=-Dgpg.passphrase=myverysupersecretpassphrase

The indirection is needed for the release action because it doesn't propagate the command line arguments directly to the spawned process (see http://maven.apache.org/plugins/maven-gpg-plugin/usage.html).