add-pr-comment

A GitHub Action which adds a comment to a pull request's issue.

Limitations

Due to how GitHub handles permissions in PRs coming from forks you will need to deploy an app if you want to post comments in those situations. See below.

Usage

on:
  pull_request:

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: mshick/add-pr-comment@v1
        with:
          message: |
            **Hello**
            🌏
            !
          repo-token: ${{ secrets.GITHUB_TOKEN }}
          repo-token-user-login: 'github-actions[bot]' # The user.login for temporary GitHub tokens
          allow-repeats: false # This is the default

You can even use it on PR Issues that are related to PRs that were merged into master, for example:

on:
  push:
    branches:
      - master

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: mshick/add-pr-comment@v1
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        with:
          message: |
            **Hello MASTER**
          allow-repeats: true

Configuration options

Variable or Argument	Location	Description	Required	Default
message	with	The message you'd like displayed, supports Markdown and all valid Unicode characters	yes
repo-token	with	A valid GitHub token, either the temporary token GitHub provides or a personal access token	maybe
repo-token-user-login	with	Define this to save on comment processing time when checking for repeats. GitHub's default token uses github-actions[bot]	no
allow-repeats	with	A boolean flag to allow identical messages to be posted each time this action is run	no	false
GITHUB_TOKEN	env	A valid GitHub token, can alternatively be defined in the env	maybe

Proxy for Fork-based PRs

GitHub limits GITHUB_TOKEN and other API access token permissions when creating a PR from a fork. This makes it impossible to add comments when your PRs are coming from forks, which is the norm for open source projects. To work around this situation I've created a simple companion app you can deploy to Cloud Run or another environment to proxy the create comment requests and escalate the token privileges.

See this issue: https://github.community/t/github-actions-are-severely-limited-on-prs/18179/4 for more detail.

Example

on:
  pull_request:

jobs:
  pr:
    runs-on: ubuntu-latest
    steps:
      - uses: mshick/add-pr-comment@v1
        with:
          message: |
            **Howdie!**
          proxy-url: https://add-pr-comment-proxy-94idvmwyie-uc.a.run.app/
          proxy-secret: foobar
          repo-token: ${{ secrets.GITHUB_TOKEN }}

Features

• Fast, runs in the GitHub Actions node.js runtime; no Docker pull needed.
• Modify issues for PRs merged to master.
• Multiple posts of the same comment optionally allowable.
• Supports emoji 😂😂😂!

Use Case

• Adding a deployed app URL to a PR issue
• Printing some sort of output to the PR issue for human-readability