Gradle: Using 'maven-publish' plugin in custom standalone plugin

Question

Almost feeling like spamming after my third question, cause my questions seem so trivial. But I just don't find any help in Gradle Docs for my cases and also other asked questions on stackoverflow weren't helping.

This time: I can't use the maven-publish plugin in my own standalone custom plugin. The code of my plugin so far:

package com.sample.gradle;

import org.gradle.api.Project;
import org.gradle.api.Plugin;

public class SampleGradlePlugin implements Plugin<Project> {
    public void apply(Project project) {

        project.apply plugin: 'application'
        project.apply plugin: 'maven-publish'
        project.apply plugin: 'maven'

        project.publishing.publications {
            maven(MavenPublication) {
                groupId project.group
                artifactId project.name
                version=project.version
                from components.java
            }
        }

        project.uploadArchives {
            repositories {
                mavenDeployer {
                    repository(url: project.Repo_Upload_Internal){
                        authentication(userName: project.Repo_Upload_User, password: project.Repo_Upload_Pass)
                    }        
                    snapshotRepository(url: project.Repo_Upload_Snapshot){
                        authentication(userName: project.Repo_Upload_User, password: project.Repo_Upload_Pass)
                    }
                }
            }
        }
        //this try/catch is not important for my question
        try{
            project.repositories {
                maven {
                    url project.Repo_Gp_Internal
                    credentials {
                        username project.Repo_Gp_User;
                    }
                }
            }
        }
        catch(MissingPropertyException e){
            println "Info: '"+e.getProperty()+"' not declared in \\"+project.name+"\\gradle.properties"
        }
    }
}

The publishing closure is the important part that brings me this error, when I use my plugin in one of my projects:

FAILURE: Build failed with an exception.

* Where:
Build file 'C:\Users\quastc\Desktop\Gradle_Projects\Application_RootProject\buil
d.gradle' line: 3

* What went wrong:
A problem occurred evaluating root project 'Application_RootProject'.
> Failed to apply plugin [id 'sample.sample-groovy-plugin']
   > Cannot create a Publication named 'MavenPublication' because this container
 does not support creating elements by name alone. Please specify which subtype
of Publication to create. Known subtypes are: MavenPublication

Where's my mistake? What did I forget?

If somebody answers, PLEASE let me know HOW you got your knowledge.

score 4 · Answer 1 · answered Sep 07 '16 at 12:09

4

In my case I fixed that error message adding this:

import org.gradle.api.publish.maven.MavenPublication

But then faced other issues and finally ended up using the nebula-publishing-plugin, solving it all

answered Sep 07 '16 at 12:09

Fabien L.D.

133
10

Building using Groovy might not throw a compile error if MavenPublication is not imported. The 'does not support creating elements by name alone' error is thrown in this case. – Steven Spungin Jul 11 '17 at 12:06

Christian Quast · Accepted Answer · 2016-08-19T10:41:36.203

Found a solution that works for me right now. I don't use the maven-publish plugin anymore. Just the maven plugin. Then I put this code at the end of my own plugin:

    project.configurations {
        deployerJars 
    }
    project.dependencies {
        deployerJars "org.apache.maven.wagon:wagon-http:2.2"
    }   
    project.uploadArchives {
        repositories {
            mavenDeployer {
                repository(url: project.Repo_Upload_Internal){
                    authentication(userName: project.Repo_Upload_User, password: project.Repo_Upload_Pass)
                }        
                snapshotRepository(url: project.Repo_Upload_Snapshot){
                    authentication(userName: project.Repo_Upload_User, password: project.Repo_Upload_Pass)
                }
            }
        }
    }

Further:

I haven't found a way to suppress the uploading of a zip and a tar file. I still need some copy&paste code in the several build.gradle files to do this job. It's this code:

configurations.archives.with {
    artifacts.remove artifacts.find { it.archiveTask.is distZip }
    artifacts.remove artifacts.find { it.archiveTask.is distTar }
}

I'm not able to change that code to work in my custom plugin yet.

FYI, the code you have to prevent uploading zip and tar files breaks with Gradle 4.x and higher. I have found a similar workaround that works on 3.x and 4.x Gradle, that appears to do the same thing, which was found on https://github.com/georocket/georocket/blob/master/georocket-server/build.gradle `// do not upload ZIP and TAR distributions to Maven repo configurations.archives.with { artifacts.removeAll { it.file =~ 'tar' } artifacts.removeAll { it.file =~ 'zip' } }` — Marcus, Sep 17 '18 at 23:34

score 1 · Answer 3 · answered Feb 07 '19 at 14:19

This worked for me, with gradle 4.10 and maven-publish.

In my custom plugin .groovy:

import org.gradle.api.publish.maven.MavenPublication

...

project.extensions.configure PublishingExtension, new ClosureBackedAction( {
                publications{
                    mycustompub(MavenPublication) {
                        groupId = project.group
                        artifactId = <artifact name>
                        artifact source: <path to artifact>, extension: 'zip'
                    }
            }})

score 0 · Answer 4 · answered Aug 19 '16 at 09:35

The closure you pass to project.publishing.publications does not have project in its context when it executes. This means MavenPublication is not in the context of the closure, even though you apply maven-plugin to project.

If you write the plugin in your build script, it will have project as context by default, but the context is different when writing it as a standalone plugin.

You can setDelegate(project) on a closure to set the context, then pass it:

def publicationsClosure =  {
    maven(MavenPublication) {
        groupId project.group
        artifactId project.name
        version=project.version
        from components.java
    }
}
publicationsClosure.setDelegate(project)
project.publishing.publications(publicationsClosure)

I had the same error in a plugin and eventually realized what went on when I read this article: http://trickyandroid.com/gradle-tip-2-understanding-syntax/

Gradle: Using 'maven-publish' plugin in custom standalone plugin

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