Trigger GitHub Actions Workflow on Pull Request Merge

The Flawed Configuration

In my personal development, I had set up a GitHub Actions workflow to run when a pull request gets merged, as shown below:

name: Some Build

on:
  pull_request:
    branches:
      - main
    types:
      - closed

jobs:
  build:
    runs-on: ubuntu-latest
    steps:

However, there was a flaw in this configuration: the workflow would also run when the pull request was closed without being merged. I wanted to modify this configuration so that the workflow only runs when a pull request gets merged.

Revised Configuration

GitHub Actions does not have a pull request-related trigger like the merged event.

Therefore, to ensure the job runs only on merge, I used the if condition as shown below:

name: Some Build

on:
  pull_request:
    branches:
      - main
    types:
      - closed

jobs:
  build:
    if: github.event.pull_request.merged == true # This line
    runs-on: ubuntu-latest
    steps:

With this setup, the workflow now only runs when a pull request is merged.

References

• https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#running-your-pull_request-workflow-when-a-pull-request-merges