A GitHub action that comments with a given message the pull request linked to the pushed branch. You can even put dynamic data thanks to Contexts and expression syntax.

on: pull_request

jobs:
  example_comment_pr:
    runs-on: ubuntu-latest
    name: An example job to comment a PR
    steps:
      - name: Checkout
        uses: actions/checkout@v3

      - name: Comment PR
        uses: thollander/actions-comment-pull-request@v3
        with:
          message: |
            Hello world ! :wave:

Thanks to the file-path input, a file content can be commented. You can either pass an absolute file-path or a relative one that will be by default retrieved from GITHUB_WORKSPACE. (Note that if both a message and file-path are provided, message will take precedence.)

- name: PR comment with file
  uses: thollander/actions-comment-pull-request@v3
  with:
    file-path: /path/to/file.txt

You can also set some reactions on your comments through the reactions input. It takes only valid reactions and adds it to the comment you've just created. (See https://docs.github.com/en/rest/reactions#reaction-types)

- name: PR comment with reactions
  uses: thollander/actions-comment-pull-request@v3
  with:
    message: |
      Hello world ! :wave:
    reactions: eyes, rocket

You can explicitly input which pull request should be commented on by passing the pr-number input. That is particularly useful for manual workflow for instance (workflow_run).

...
- name: Comment PR
  uses: thollander/actions-comment-pull-request@v3
  with:
    message: |
      Hello world ! :wave:
    pr-number: 123 # This will comment on pull request #123

Editing an existing comment is also possible thanks to the comment-tag input.

Thanks to this parameter, it will be possible to identify your comment and then to upsert on it. If the comment is not found at first, it will create a new comment.

That is particularly interesting while committing multiple times in a PR and that you just want to have the last execution report printed. It avoids flooding the PR.

...
- name: Comment PR with execution number
  uses: thollander/actions-comment-pull-request@v3
  with:
    message: |
      _(execution **${{ github.run_id }}** / attempt **${{ github.run_attempt }}**)_
    comment-tag: execution

Note: the input mode can be used to either upsert (by default) or recreate the comment (= delete and create)

Deleting a comment with a specific comment-tag is possible with the mode: delete. If a comment with the comment-tag exists, it will be deleted when ran.

...
- name: Delete a comment
  uses: thollander/actions-comment-pull-request@v3
  with:
    comment-tag: to_delete
    mode: delete

Deleting an existing comment on job completion is also possible thanks to the comment-tag input combined with mode: delete-on-completion.

This will delete the comment at the end of the job.

...
- name: Write a comment that will be deleted at the end of the job
  uses: thollander/actions-comment-pull-request@v3
  with:
    message: |
      The PR is being built...
    comment-tag: to_delete_on_completion
    mode: delete-on-completion

You can get some outputs from this actions :

- name: Comment PR
  uses: thollander/actions-comment-pull-request@v3
  id: hello
  with:
    message: |
      Hello world ! :wave:
- name: Check outputs
  run: |
    echo "id : ${{ steps.hello.outputs.id }}"
    echo "body : ${{ steps.hello.outputs.body }}"
    echo "html-url : ${{ steps.hello.outputs.html-url }}"

Depending on the permissions granted to your token, you may lack some rights. To run successfully, this actions needs at least :

permissions: 
   pull-requests: write 

Add this in case you get Resource not accessible by integration error. See jobs.<job_id>.permissions for more information.

Note that, if the PR comes from a fork, it will have only read permission despite the permissions given in the action for the pull_request event. In this case, you may use the pull_request_target event. With this event, permissions can be given without issue (the difference is that it will execute the action from the target branch and not from the origin PR).

The build steps transpiles the src/main.ts to lib/index.js which is used in a NodeJS environment. It is handled by vercel/ncc compiler.

$ npm run build