Publishing a Gradle precompiled script plugin to a custom repository

README.txt

Gradle plugins require a marker:
https://docs.gradle.org/current/userguide/plugins.html#sec:plugin_markers

Markers aren't published for precompiled scripts using groovy-gradle-plugin :(
https://github.com/gradle/gradle/issues/15190

The plugin_marker module creates the marker that Gradle needs to find the plugin and also publishes it,
see https://stackoverflow.com/a/60798021/5793905

Assuming all gradle modules have the same group with a folder structure like:

- build.gradle
--> plugin/
----> build.gradle
----> src/main/groovy/foo.gradle

----> marker/
------> build.gradle

Replace underscores with forward slashes in file names below.

build.gradle

allprojects {
    group "com.foo.bar"
    version "0.0.0-SNAPSHOT"
    
    afterEvaluate {
        if (project.plugins.hasPlugin("groovy-gradle-plugin")) {
            // names of META-INF/gradle-plugins/*.properties files in the jars don't include group for some reason... Gradle needs that convention
            pluginDescriptors {
                afterEvaluate {
                    declarations.get().each { PluginDeclaration declaration ->
                        declaration.id = "${project.group}.${declaration.id}"
                    }
                }
            }
        }
    }
}

plugin_build.gradle

plugins {
    id "groovy-gradle-plugin"
}

/* optional
dependencies {
    api ...
}
*/

plugin_marker_build.gradle

plugins {
    id "java-library"
    id "maven-publish"
}

group = "${group}.${project.parent.name}"

dependencies {
    implementation project(":${project.parent.name}")
}

publishing {
    repositories {
        maven {
            url "foo"
            credentials {
                username = "bar"
                password = "baz"
            }
        }
    }
    publications {
        pluginMarker(MavenPublication) {
            artifactId = "${project.group}.gradle.plugin"
            pom.withXml {
                asNode().children().last() + {
                    resolveStrategy = Closure.DELEGATE_FIRST

                    dependencies {
                        project.configurations.each { conf ->
                            conf.dependencies.each { dep ->
                                dependency {
                                    groupId dep.group
                                    artifactId dep.name
                                    version dep.version
                                }
                            }
                        }
                    }
                }
            }
        }
    }
}