Danger PR Comment

Reusable GitHub Actions workflows for running Danger and posting a PR comment from a JSON report.

Usage

Quick Install

From your repository root:

curl -fsSL https://raw.githubusercontent.com/numbata/danger-pr-comment/main/scripts/install-workflows.sh | bash

Use --force to overwrite existing workflow files. To target a specific directory:

curl -fsSL https://raw.githubusercontent.com/numbata/danger-pr-comment/main/scripts/install-workflows.sh | bash -s -- --root /path/to/repo

Manual Setup

Create .github/workflows/danger.yml in your repository:

name: Danger
on:
  pull_request:
    types: [opened, reopened, edited, synchronize]

jobs:
  danger:
    uses: numbata/danger-pr-comment/.github/workflows/danger-run.yml@main
    secrets: inherit

Create .github/workflows/danger-comment.yml in your repository:

name: Danger Comment
on:
  workflow_run:
    workflows: [Danger]
    types: [completed]

jobs:
  comment:
    uses: numbata/danger-pr-comment/.github/workflows/danger-comment.yml@main
    secrets: inherit

Requirements

• Your repository must run bundle exec danger successfully.
• Your Dangerfile must write a JSON report to ENV['DANGER_REPORT_PATH'] (for example, via a custom at_exit hook or a shared Dangerfile).
• The Danger Comment workflow needs actions: read and issues: write permissions to download artifacts and post comments.

Dangerfile report example

If you want a shared Dangerfile, add the gem and import it:

# Gemfile
gem 'danger-pr-comment', require: false

# Dangerfile
# Import danger-pr-comment for automatic danger report export
danger.import_dangerfile(gem: 'danger-pr-comment')

Or add this to your project's Dangerfile (or a shared Dangerfile) to emit the JSON report yourself:

# Dangerfile
require 'json'
require 'English'

dangerfile_instance = self if defined?(Danger::Dangerfile) && is_a?(Danger::Dangerfile)
at_exit do
  next if $ERROR_INFO && !$ERROR_INFO.is_a?(SystemExit)
  next unless dangerfile_instance

  report_path = ENV.fetch('DANGER_REPORT_PATH', nil)
  event_path = ENV.fetch('GITHUB_EVENT_PATH', nil)
  next unless report_path && event_path && File.exist?(event_path)

  event = JSON.parse(File.read(event_path))
  pr_number = event.dig('pull_request', 'number')
  next unless pr_number

  to_messages = lambda do |items|
    Array(items).map { |item| item.respond_to?(:message) ? item.message : item.to_s }
  end

  report = {
    pr_number: pr_number,
    errors: to_messages.call(dangerfile_instance.status_report[:errors]),
    warnings: to_messages.call(dangerfile_instance.status_report[:warnings]),
    messages: to_messages.call(dangerfile_instance.status_report[:messages]),
    markdowns: to_messages.call(dangerfile_instance.status_report[:markdowns])
  }

  File.write(report_path, JSON.pretty_generate(report))
end

Inputs

danger-run.yml inputs:

• ruby-version: Ruby version for ruby/setup-ruby. Leave empty to use .ruby-version/.tool-versions.
• bundler-cache: Enable Bundler caching (default true).
• danger-args: Arguments passed to bundle exec danger (default dry_run).
• report-artifact-name: Artifact name for the report (default danger-report).
• report-file: Report filename (default danger-report.json).

danger-comment.yml inputs:

• report-artifact-name: Artifact name to download (default danger-report).
• report-file: Report filename inside the artifact (default danger-report.json).
• comment-title: Heading for the PR comment (default Danger Report).
• comment-marker: Marker string used to update the comment (default <!-- danger-report -->).

License

MIT License. See LICENSE for details.