Action does not get triggered for last commit when base branch is changed

[R1j1t]

Describe the bug
When the base branch of the PR is changed, action does not get triggered for the last commit in that PR.

To Reproduce
Steps to reproduce the behavior:

1. Create a Pull Request
2. Change the base branch for which actions should be triggered for PR
3. No ci trigger

Expected behavior
what I was expecting was actions to be triggered for the last commit in the PR. Wanted to check if it is not the expected behavior.

Runner Version and Platform

Version of your runner? Public Github

OS of the machine running the runner? OSX/Windows/Linux/...
NA

What's not working?

Github action not getting triggered.

Job Log Output

R1j1t/contextualSpellCheck#49 (comment) link to base branch change in PR.

Runner and Worker's Diagnostic Logs

NA

[R1j1t]

Please let me know if this is the right repository for this issue.

[thboop]

Hey @R1j1t ,

The pull request event has a variety of triggers, by default we subscribe to opened, synchronize, or reopened. You can read more about those here: https://docs.github.com/en/actions/reference/events-that-trigger-workflows#pull_request

Changing the base ref is the edited action, you can subscribe to those as well by doing

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

However, edited applies to more than just changing the base ref, for example changing the title of the pr will also trigger the edited action.

You may filter these down using expressions, the github context stores information about why the edited event was triggered, for example:

    "event": {
      "action": "edited",
      "changes": {
        "base": {
          "ref": {
            "from": "main"
          },
          "sha": {
            "from": "{some sha here}"
          }
        }
      },

For more information on how to filter jobs based on the value of the context, please see our official docs

I've brought feedback to the team that we should consider an event for only base ref changes as an enhancement and add it by default, but it's not currently available and I don't have a timeline for when it may be available.

I'm going to close this issue for now, but feel free to reopen it if you have any more questions!

[R1j1t]

Thanks @thboop for the detailed explanation. It definitely answers all the question I had. I will check the documentation to learn more about it. I really appreciate the quick response!

[AllanOricil]

@thboop help me with this issue. For some reason Im editing the Title of the PR and it does not start the action. Sometimes it does, but I can't understand why it does it sometimes.

https://github.bokerqi.topmunity/t/action-not-starting-when-editing-the-title-or-description-of-a-pr/216836

[michalinacienciala]

Hi @thboop, the doc you linked (https://docs.github.com/en/actions/reference/events-that-trigger-workflows#pull_request) refers to https://docs.github.com/en/developers/webhooks-and-events/webhooks/webhook-events-and-payloads#pull_request for more information on activity types. In that doc about webhook events, the synchronize activity is described as this:

Triggered when a pull request's head branch is updated. For example, when the head branch is updated from the base branch, when new commits are pushed to the head branch, or when the base branch is changed.

Is that fragment of documentation out-of-date?

[LinusU]

@thboop has there been any more talks internally about adding this as a default?

It's quite surprising that workflow doesn't get triggered when the base branch is changed with e.g. the following configuration:

on:
  pull_request:
    branches:
    - master

[cakeinpanic]

@michalinacienciala I assume that "base branch is changed" means not that new commits are pushed to master, but master is replaced with dev or smth ike this