How to make gradle generate a valid pom.xml file at the root of a project for maven users?

Question

While only for two days now, I am definitely sold on using gradle for all of my Java projects, and drop pom.xml from the root of all my projects.

However, I would like to remain maven-compatible, in the sense that I would like for a gradle task to be able to generate a suitable pom.xml at the root of the project should the user want it.

At this moment, the only reference to a pom.xml I have is in this section of the build.gradle file (this is, with very few modifications, what is found here):

uploadArchives {
    repositories {
        mavenDeployer {
            beforeDeployment {
                MavenDeployment deployment -> signing.signPom(deployment);
            }

            repository(url: sonatypeRepoURI) {
                authentication(userName: sonatypeUsername,
                    password: sonatypePassword);
            }

            pom.project {
                name "${name}";
                packaging "bundle";
                description "${description}";
                url "${projectURL}";

                scm {
                    url "${gitroscm}";
                    connection "${gitroscm}";
                    developerConnection "${gitrwscm}";
                }

                licenses {
                    license {
                        name "Lesser General Public License, version 3 or greater";
                        url "http://www.gnu.org/licenses/lgpl.html";
                        distribution "repo";
                    }
                }

                developers {
                    developer {
                        id "whocares";
                        name "whocares";
                        email "whocares";
                    }
                }
            }
        }
    }
}

How would I extract the pom.project out of this very deeply nested construct into a task which could generate a pom.xml (by default, the generated pom.xml is in build/poms/pom-default.xml and looks quite good)?

More importantly, is it possible to extract that pom.project out of uploadArchives while still being able to refer to it?

Full link to the build.gradle file: here.

Did you look at gradle.org/docs/current/userguide/maven_plugin.html#N1511A , I haven't used it, but it looks like what you're describing. — jmruc
@KirilRaychev this looks interesting, but integrating it into the existing execution flow is where I am at a loss :/ — fge
If you want to build the pom manually, just run the writeNewPom task. If you want to generate a pom on each build, add build.dependsOn writeNewPom to your build.grade — jmruc
Uh, I already have the maven plugin loaded... And gradle writeNewPom fails saying it cannot find the task! — fge
Work's fine for me - look at this example build.gradle - gist.github.com/jmruc/5852692 — jmruc

jmruc jmruc · Accepted Answer · 2013-06-24T19:49:35

You can use the gradle maven plugin. This adds the pom convention method to your project, which you can use in a task to generate a pom.xml file, like

task writeNewPom {
    doLast {
        pom {
            project {
                groupId 'org.example'
                artifactId 'test'
                version '1.0.0'
                inceptionYear '2008'
                licenses {
                    license {
                        name 'The Apache Software License, Version 2.0'
                        url 'http://www.apache.org/licenses/LICENSE-2.0.txt'
                        distribution 'repo'
                    }
                }
            }
        }.writeTo("pom.xml")
    }
}

Then you call gradle createPom to generate the pom.xml in the project root. Of all the things in the pom definition, you should really provide groupId, artifactId and version, other thins like licenses are not that important.

You can also look at this example for a project definition with some dependencies, and try running it to see what it produces.

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How to make gradle generate a valid pom.xml file at the root of a project for maven users?

2 Answers