action-pr-publishing

An action for publishing PRs to a GitHub Packages.

How it works

The action is split into two steps:

Step 1 - the upload

This step can be part of a pull_request workflow, as it does not need secrets.
The actions in this step:

Prepare a Gradle init script that adds a new, _githubPackages_PRs repository to all projects that have the maven-publish plugin applied, and that points to a local directory;
Run the publishAllPublicationsTo_githubPackages_PRsRepository Gradle task;
Pack the workflow event payload alongside the local maven directory into a workflow artifact named maven-publish.

Step 2 - the publishing

This step must be run with a workflow_run dispatch listening for the workflow that runs the first step.
Additionally, this step requires the following permissions:

permissions:
  packages: write # To upload the PR
  actions: write # To get information about the uploading workflow run and to delete the run artifacts
  contents: write # To download the `maven-publish` artifact, and to be able to create commit comments
  issues: write # To be able to create PR comments
  pull-requests: write # To be able to create PR comments

The actions in this step:

Process information about the uploading workflow run. If not successful, abort;
Download the maven-publish artifact that was uploaded by the uploading workflow;
Upload the (filtered) contents of the artifact to a GitHub sub-package of the repository, that has the pr<number>. prefix; delete the workflow artifact so that in the future re-publishing is not attempted;
OPTIONAL STEP, only if the repository's name is NeoForge: generate an MDK pointing to the published version of the PR (more information on mdk generation below);
Comment on the PR with information on the published artifacts (and an MDK link and installer link if necessary), or update an existing comment;

MDK Generation

If the name of the repository this action runs on is NeoForge (case insensitive), the action will generate an MDK.
The branch of the MDK being used as base will be decided based on the Minecraft component of the artifact version (i.e. the 20.2 in 20.2-beta-pr1). The expected branch name is 1.<component> (i.e. 1.20.2). If such branch is not found, the action will use the main branch as the base.

Replacements:

A line starting with exactly neo_version= in the gradle.properties file will be updated with the published artifact version;
A line starting with exactly minecraft_version= in the gradle.properties file will be updated with the correct Minecraft version (relevant if the base branch is main);
The PR repository declaration block will be added before a dependencies { line.