Any way to checkout PR from issue_comment event?

[aaronsteers]

The example in the docs here assumes a pull request event, but it does not work when operating on Pull Request comments, since those come through the issue_comment event.

I've spent several hours on this now and I don't see any way to checkout the branch associated with the issue_event.

Complications:

• The event is the comment and it links to an issue, which only indirectly seems to have data on the pull request url.
• Checking out the associate sha doesn't give push ability, since the branch name itself is not discoverable (at least not as well as I can tell).
• Since issue_comment events have to be triggered by the workflow file on the default branch, it seems that is always the branch name provided. I haven't yet found any way to get the actual PR branch, although it seems this should be a straightforward and frequent use case for operating on PR comments.

[aaronsteers]

The only solution I found was to first use the checkout event and then separately use hub CLI, which is apparently installed by default and which can run hub pr checkout ${pr_num} in order to checkout whatever branch is associated with the PR (after parsing the PR num from the URL).

name: Slash Command CI

on: issue_comment

jobs:
  check_comments:
    runs-on: ubuntu-latest
    name: Check comments for /format
    steps:
      - name: Clone git repo
        uses: actions/checkout@v2
      - name: Checkout Pull Request
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: |
          PR_URL="${{ github.event.issue.pull_request.url }}"
          PR_NUM=${PR_URL##*/}
          echo "Checking out from PR #$PR_NUM based on URL: $PR_URL"
          hub pr checkout $PR_NUM
      - name: Configure Git Agent
        run: |
          git config --global user.email "my.email@sample.com"
          git config --global user.name "Me, Not Really (CI bot)"
      - uses: hashicorp/setup-terraform@v1
        with:
          terraform_version: 0.13.0
      - run: terraform fmt -recursive
      - run: git commit -a -m "GitOps Bot (Autoformat)"
      - run: git push

Is there a better way?

[NutanNiraula]

I faced the same problem with one more restriction that github account was not owned by us, I don't know the context that other users will face but in my case I can just send in the branch name through the comment. so, here is what I did:

Basically pull out branch name from comment where branch name is enclosed in [], i.e [branch_name] then extract out the name to pass it to the checkout action. I would love to find better way than this but for now it works ok.

steps:
    - name: Get Branch name
      id: branchName
      run: |
        echo ::set-output name=branch::$(echo $PR_COMMENT | cut -d "[" -f2 | cut -d "]" -f1)
      env:
        PR_COMMENT: ${{ github.event.comment.body }}
    - name: Checkout code
      uses: actions/checkout@v2
      with: 
        ref: ${{ steps.branchName.outputs.branch }}

[Simran-B]

As the required information isn't present in the event payload, you could use the GitHub API to fetch it. The github-script action allows you to write actions in your workflow file, which is pretty convenient:

name: Checkout PR on comment

on:
  issue_comment:
    # triggers on created, edited and deleted by default, you may wanna restrict it, e.g.:
    #types: [created]
jobs:
  pr-commented:
    name: PR commented
    if: github.event.issue.pull_request
    runs-on: ubuntu-latest
    steps:
      - uses: actions/github-script@v3
        id: get-pr
        with:
          script: |
            const request = {
              owner: context.repo.owner,
              repo: context.repo.repo,
              pull_number: context.issue.number
            }
            core.info(`Getting PR #${request.pull_number} from ${request.owner}/${request.repo}`)
            try {
              const result = await github.pulls.get(request)
              return result.data
            } catch (err) {
              core.setFailed(`Request failed with error ${err}`)
            }
      - uses: actions/checkout@v2
        with:
          repository: ${{ fromJSON(steps.get-pr.outputs.result).head.repo.full_name }}
          ref: ${{ fromJSON(steps.get-pr.outputs.result).head.sha }} # or .head.ref for branch name

[zyv]

The only solution I found was to first use the checkout event and then separately use hub CLI, which is apparently installed by default and which can run hub pr checkout ${pr_num} in order to checkout whatever branch is associated with the PR (after parsing the PR num from the URL).

Is there a better way?

@aaronsteers do you even need to parse it? I though the following should do:

hub pr checkout ${{ github.event.issue.number }}

[aaronsteers]

The only solution I found was to first use the checkout event and then separately use hub CLI, which is apparently installed by default and which can run hub pr checkout ${pr_num} in order to checkout whatever branch is associated with the PR (after parsing the PR num from the URL).

Is there a better way?

@aaronsteers do you even need to parse it? I though the following should do:

hub pr checkout ${{ github.event.issue.number }}

@zyv , yes, I think it would! The 10-months-ago-me perhaps didn't know or realize yet that a PR is an issue and the issue number is therefore the same as the PR number. 🙌

[rongquantoh-intel]

Can we add PR information like target branch or source branch in issue_comment webhook payload?
These should be very commonly used.

[mareksuscak]

The only solution I found was to first use the checkout event and then separately use hub CLI, which is apparently installed by default and which can run hub pr checkout ${pr_num} in order to checkout whatever branch is associated with the PR (after parsing the PR num from the URL).
Is there a better way?

@aaronsteers do you even need to parse it? I though the following should do:

hub pr checkout ${{ github.event.issue.number }}

This has worked for us!

deploy:
  runs-on: ubuntu-latest
  steps:
    # Checkout source code
    - name: Checkout
      uses: actions/checkout@v2
    - name: Checkout Pull Request
      run: hub pr checkout ${{ github.event.issue.number }}
      env:
        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

[tomdottom]

Edit: The below information is not correct as pointed out by @zyv below

- uses: actions/checkout@v2
  with:
    ref: ${{ github.event.pull_request.head.sha }}

• https://frontside.com/blog/2020-05-26-github-actions-pull_request/

[zyv]

@tomdottom this information is not available in issue_comment event.

[tomdottom]

@tomdottom this information is not available in issue_comment event.

@zyv thanks for pointing this out

[suonto]

I just created a tiny js action that will output base_ref and head_ref: https://github.com/eficode/resolve-pr-refs

It's really simple to use:

- name: resolve pr refs
  id: refs
  uses: eficode/resolve-pr-refs@main
  with:
    token: ${{ secrets.GITHUB_TOKEN }}

In the following steps you can reference ${{ steps.refs.outputs.head_ref }} and ${{ steps.refs.outputs.base_ref }}

I hope you like it 🙂

[jacobrask]

In case anyone else comes looking, you can use the gh cli to only get the branch name if you still want to use the actions/checkout action

    steps:
      - id: 'get-branch'
        run: echo ::set-output name=branch::$(gh pr view $PR_NO --repo $REPO --json headRefName --jq '.headRefName')
        env:
          REPO: ${{ github.repository }}
          PR_NO: ${{ github.event.issue.number }}
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

      - name: Checkout
        uses: actions/checkout@v2
        with:
          ref: ${{ steps.get-branch.outputs.branch }}

[AllanOricil]

@jacobrask I tried your solution and I received the following output:

GraphQL: Resource not accessible by integration (repository.pullRequest)

What else did you do?

[NickCrews]

@mareksuscak's method worked great for my on: issue_comment triggered workflow. Pretty sure you can't get much shorter or faster than this!

deploy:
  runs-on: ubuntu-latest
  steps:
    # need this first step to init the git repo
    - name: Checkout
      uses: actions/checkout@v2
    - name: Checkout Pull Request
      run: hub pr checkout ${{ github.event.issue.number }}
      env:
        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

[ADTC]

@niklasnatter you have THE PERFECT SOLUTION! Thank you.

      - name: Checkout pull request 🏁
        uses: actions/checkout@v3
        with:
          ref: refs/pull/${{ github.event.issue.number }}/head

[Zhiyuan-Amos]

Did some testing and realised there's some slight differences between some of the answers above. This answer actually checks out the PR branch

steps:
  - id: 'get-branch'
    run: echo ::set-output name=branch::$(gh pr view $PR_NO --repo $REPO --json headRefName --jq '.headRefName')
    env:
      REPO: ${{ github.repository }}
      PR_NO: ${{ github.event.issue.number }}
      GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

  - name: Checkout
    uses: actions/checkout@v2
    with:
      ref: ${{ steps.get-branch.outputs.branch }}

While this answer checks out the latest commit of the PR branch

  - name: Checkout pull request 🏁
    uses: actions/checkout@v3
    with:
      ref: refs/pull/${{ github.event.issue.number }}/head

My use case involves linting code (triggered by slash command /lint) and committing the changes. The 2nd answer doesn't work for me as the git push command errors out with fatal: You are not currently on a branch.

[ADTC]

Great discovery @Zhiyuan-Amos I will add your comment in my PR if that's okay with you.

[dcantu96]

has anyone found a way to find the ref of the pr with this issue_comment trigger event ?

as far as I know github.event.issue.pull_request.ref doesnt work :/ i'd like a solution that avoids using octokit

[hakuno]

Hey everybody, I noticed that GitHub creates refs for pull request commits: https://www.jvt.me/posts/2019/01/19/git-ref-github-pull-requests/ This allows to checkout the branch of the pull request directly in the actions/checkout@v3 action:

      - name: Checkout pull request 🏁
        uses: actions/checkout@v3
        with:
          ref: refs/pull/${{ github.event.issue.number }}/head

I changed that for me to support both triggers (issue_comment or any other like workflow_dispatch):

- uses: actions/checkout@v4
  with:
    ref: ${{ github.event_name == 'issue_comment' && format('refs/pull/{0}/head', github.event.issue.number) || '' }}