Gradle, JVM and GitHub Packages

Initial comment this is mainly done as a reminder to myself.

So about 6 months ago GitHub launched a new exciting service; GitHub Package Registry. This service lets you as a GitHub-user upload your Open Source code for free on GitHubs registry supporting a wide array of languagues and build systems - JavaScript (npm), Java/JVM-languages (Maven/Gradle), Ruby (RubyGems), .NET (NuGet), and Docker images. Perhaps more have been added since I last verified.

In this post I’ll try to keep to the point and give clear easy instruction that you’ll be able to bookmark and go back to whenever you need to set this up.

I’ll give the instruction directly beneath with some comments afterwards for the one who’d like to read some extra.

1. Add Maven Publish Plugin

build.gradle.kts

plugins {
    `maven-publish` // Add this
    kotlin(\"jvm\") version \"1.3.60\"
}

build.gradle

plugins {
    id(\"maven-publish\")
}

build.gradle (using the old apply way of things)

apply plugin: 'maven-publish'

2. Add Publication Part

build.gradle.kts

publishing {
    repositories {
        maven {
            name = \"GitHubPackages\"
            url = uri(\"https://maven.pkg.github.com/OWNER/REPO\")
            credentials {
                username = project.findProperty(\"gpr.user\") as String? ?: System.getenv(\"GITHUB_ACTOR\")
                password = project.findProperty(\"gpr.key\") as String? ?: System.getenv(\"GITHUB_TOKEN\")
            }
        }
    }
    publications {
        register<MavenPublication>(\"gpr\"){
            from(components[\"java\"])
        }
    }
}

build.gradle

publishing {
    repositories {
        maven {
            name = \"GitHubPackages\"
            url = uri(\"https://maven.pkg.github.com/OWNER/REPOSITORY\")
            credentials {
                username = project.findProperty(\"gpr.user\") ?: System.getenv(\"GITHUB_ACTOR\")
                password = project.findProperty(\"gpr.key\") ?: System.getenv(\"GITHUB_TOKEN\")
            }
        }
    }
    publications {
        gpr(MavenPublication) {
            from(components.java)
        }
    }
}

3. Automating Release Workflow

To simplify our lifes further;

JitPack is already automated and tracking your repository automatically adding the new releases ones a release is created.
GitHub is not automated and we need to upload our assets

Automating GitHub packages upload through release & GitHub Actions

We’ll use GitHub Actions to create a workflow where once a release passes stage ‘published’ the assets will be uploaded to the repository/artifactory of GitHub Packages. This integration is really awesome as once we’ve set it up we only need to press "Create Release" on the GitHub page to deploy our library to both GitHub Packages & JitPack!

Create the directory .github/workflows in your root-folder of the project if it doesn’t exist yet. Add the following file:

name: Release & Publish Build

on:
  release:
    types: [published]

jobs:
  build:
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v1

      - name: Set up JDK 1.8
        uses: actions/setup-java@v1
        with:
          java-version: 1.8

      - name: Clean Build
        run: ./gradlew clean build

      - name: Publish Build
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: ./gradlew publish

The secrets.GITHUB_TOKEN is automatically supplied by GitHub itself during the run of the GitHub Actions-script.

Pretty awesome right? Go build your libraries and deploy!