binder-badge.yml

# Add Binder Link for testing a branch when a PR comment with `/binder` is made
# https://mybinder.readthedocs.io/en/latest/howto/gh-actions-badges.html#example-2-comment-with-a-binder-badge-in-response-to-a-comment
name: AddBinderBadge
on: [issue_comment] # issues and PRs are equivalent in terms of comments for the GitHub API

permissions: {}

jobs:
  trigger-chatops:
    # Make sure the comment is on a PR, and contains the command "/binder"
    if: (github.event.issue.pull_request != null) && contains(github.event.comment.body, '/binder')
    runs-on: ubuntu-slim
    permissions:
      pull-requests: write

    steps:
      # Use the GitHub API to:
      #  (1) Get the branch name of the PR that has been commented on with "/binder"
      #  (2) make a comment on the PR with the binder badge
      - name: comment on PR with Binder link
        uses: actions/github-script@3a2844b7e9c422d3c10d287c895573f7108da1b3 # v9.0.0
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          script: |
            // Get the branch name
            github.rest.pulls.get({
              owner: context.repo.owner,
              repo: context.repo.repo,
              pull_number: context.payload.issue.number
            }).then( (pr) => {

              // use the branch name to make a comment on the PR with a Binder badge
              var BRANCH_NAME = pr.data.head.ref
              github.rest.issues.createComment({
                issue_number: context.payload.issue.number,
                owner: context.repo.owner,
                repo: context.repo.repo,
                body: `[![Binder](https://mybinder.org/badge_logo.svg)](https://mybinder.org/v2/gh/${context.repo.owner}/${context.repo.repo}/${BRANCH_NAME}) :point_left: Launch a binder notebook on this branch`
              })
            })