automerge-action

GitHub action to automatically merge pull requests when they are ready.

When added, this action will run the following tasks on pull requests with the automerge label:

Changes from the base branch will automatically be merged into the pull request (only when "Require branches to be up to date before merging" is enabled in the branch protection rules)
When the pull request is ready, it will automatically be merged. The action will only wait for status checks that are marked as required in the branch protection rules
Pull requests without any configured labels will be ignored

Labels, merge and update strategies are configurable, see Configuration.

A pull request is considered ready when:

the required number of review approvals has been given (if enabled in the branch protection rules) and
the required checks have passed (if enabled in the branch protection rules) and
the pull request is up to date (if enabled in the branch protection rules)

After the pull request has been merged successfully, the branch will not be deleted. To delete branches after they are merged, see automatic deletion of branches.

This functionality is now available directly in GitHub as auto-merge. Note that GitHub does not currently support auto-rebasing pull requests. The automerge-action project will still be maintained, but users are encouraged to switch to auto-merge for simple workflows, as it offers a faster and more stable experience.

Usage

Create a new .github/workflows/automerge.yml file:

name: automerge
on:
  pull_request:
    types:
      - labeled
      - unlabeled
      - synchronize
      - opened
      - edited
      - ready_for_review
      - reopened
      - unlocked
  pull_request_review:
    types:
      - submitted
  check_suite:
    types:
      - completed
  status: {}
jobs:
  automerge:
    runs-on: ubuntu-latest
    permissions:
      contents: write
      pull-requests: write
    steps:
      - id: automerge
        name: automerge
        uses: "pascalgn/automerge-action@v0.16.4"
        env:
          GITHUB_TOKEN: "${{ secrets.GITHUB_TOKEN }}"

For the latest version, see the list of releases.

Configuration

The following merge options are supported:

MERGE_LABELS: The labels that need to be present for a pull request to be merged (using MERGE_METHOD). The default value is automerge.

This option can be a comma-separated list of labels that will be checked. All labels in the list need to be present, otherwise the pull request will be skipped (until all labels are present). Labels prefixed with an exclamation mark (!) will block a pull request from being merged, when present.

For example, when automerge,!wip,!work in progress is given, any pull requests with the labels wip or work in progress and any pull requests without the label automerge will not be merged. Blocking labels take precedence, so if a pull request has both labels wip and automerge, it will not be merged.

When an empty string ("") is given, all pull requests will be merged.
MERGE_REMOVE_LABELS: The labels to automatically remove from a pull request once it has been merged by the action. The default value is "".

This option can be a comma-separated list of labels that will be removed.

When an empty string ("") is given, no labels will be removed.
MERGE_METHOD: Which method to use when merging the pull request into the base branch. Possible values are merge (create a merge commit), rebase (rebase all commits of the branch onto the base branch) or squash (squash all commits into a single commit). The default option is merge.
MERGE_METHOD_LABELS: Set to allow labels to determine the merge method (see MERGE_METHOD for possible values). For example, automerge=merge,autosquash=squash. If no such label is present, the method set by MERGE_METHOD will be used. The default value is "".
MERGE_METHOD_LABEL_REQUIRED: Set to "true" to require one of the MERGE_METHOD_LABELS to be set. The default value is "false".
MERGE_COMMIT_MESSAGE: The commit message to use when merging the pull request into the base branch. Possible values are automatic (use GitHub's default message), pull-request-title (use the pull request's title), pull-request-description (use the pull request's description), pull-request-title-and-description or a literal value with optional placeholders (for example Auto merge {pullRequest.number}). The default value is automatic.
MERGE_COMMIT_MESSAGE_REGEX: When using a commit message containing the PR's body, use the first capturing subgroup from this regex as the commit message. Can be used to separate content that should go with the commit into the code base's history from boilerplate associated with the PR (licensing notices, check lists, etc). For example, (.*)^--- would keep everything up until the first 3-dash line (horizontal rule in MarkDown) from the commit message. The default value is empty, which disables this feature.
MERGE_FILTER_AUTHOR: When set, only pull requests raised by this author will be merged automatically.
MERGE_FORKS: Whether merging from external repositories is enabled or not. By default, pull requests with branches from forked repositories will be merged the same way as pull requests with branches from the main repository. Set this option to "false" to disable merging of pull requests from forked repositories. The default value is "true".
MERGE_RETRIES and MERGE_RETRY_SLEEP: Sometimes, the pull request check runs haven't finished yet, so the action will retry the merge after some time. The number of retries can be set with MERGE_RETRIES. The default number of retries is 6 and setting it to 0 disables the retry logic. MERGE_RETRY_SLEEP sets the time to sleep between retries, in milliseconds. The default is 5000 (5 seconds) and setting it to 0 disables sleeping between retries.
MERGE_REQUIRED_APPROVALS: Count of required approvals. The default is 0.
MERGE_DELETE_BRANCH: Automatic deletion of branches does not work for all repositories. Set this option to "true" to automatically delete branches after they have been merged. The default value is "false".
MERGE_DELETE_BRANCH_FILTER: A comma-separated list of branches that will not be deleted. This is not the list of GitHub's protected branches, which are never deleted, but an additional list of branches to protect. The default value is "".
MERGE_ERROR_FAIL: Set this to "true" to have the action exit with error code 1 when the pull request could not be merged successfully during a run.
MERGE_READY_STATE: The state(s) of a pull request for which to attempt a merge. This option can be a comma-separated list of states that will be considered mergeable. The default value is clean,has_hooks,unknown,unstable.

The following update options are supported:

UPDATE_LABELS: The labels that need to be present for a pull request to be updated (using UPDATE_METHOD). The default value is automerge.

Note that updating will only happen when the option "Require branches to be up to date before merging" is enabled in the branch protection rules.

This option can be a comma-separated list of labels, see the MERGE_LABELS option for more information.
UPDATE_METHOD: Which method to use when updating the pull request to the base branch. Possible values are merge (create a merge commit) or rebase (rebase the branch onto the head of the base branch). The default option is merge.

When the option is rebase and the rebasing failed, the action will exit with error code 1. This will also be visible in the pull request page, with a message like "this branch has conflicts that must be resolved" and a list of conflicting files.
UPDATE_RETRIES and UPDATE_RETRY_SLEEP: Sometimes, the pull request check runs haven't finished yet and the action doesn't know if an update is necessary. To query the pull request state multiple times, the number of retries can be set with UPDATE_RETRIES. The default number of retries is 1 and setting it to 0 disables the retry logic. UPDATE_RETRY_SLEEP sets the time to sleep between retries, in milliseconds. The default is 5000 (5 seconds) and setting it to 0 disables sleeping between retries.

Also, the following general options are supported:

GITHUB_TOKEN: This should always be "${{ secrets.GITHUB_TOKEN }}". However, in some cases it can be useful to run this action as a certain user (by default, it will run as github-actions). This can be useful if you want to use the "Restrict who can push to matching branches" option in the branch protection rules, for example.

To use this setting for manually providing a token, you need to create a personal access token for the user (make sure to check public_repo when it's a public repository or repo when it's a private repository). All API requests (merge/rebase) will then be executed as the specified user. The token should be kept secret, so make sure to add it as secret, not as environment variable, in the GitHub workflow file!
PULL_REQUEST: If provided, this action will attempt to merge the specified pull request. By default, it will attempt to use the pull request specified in the GitHub context. If a pull request number is provided via this input, this action will search in the current repo for the provided pull request number. If you want to merge a pull request in another repo, just provide the repo slug before the pull request number, like Some-Org/Some-Repo/1234
BASE_BRANCHES: If provided, the action will be restricted in terms of base branches. Can be comma-separated list of simple branch names (i.e main,dev).
MAX_PR_COUNT: If provided, will control how many GitHub pull requests are considered in a single run. The default is 10.

You can configure the environment variables in the workflow file like this:

        env:
          GITHUB_TOKEN: "${{ secrets.GITHUB_TOKEN }}"
          MERGE_LABELS: "automerge,!work in progress"
          MERGE_REMOVE_LABELS: "automerge"
          MERGE_METHOD: "squash"
          MERGE_COMMIT_MESSAGE: "pull-request-description"
          MERGE_FORKS: "false"
          MERGE_RETRIES: "6"
          MERGE_RETRY_SLEEP: "10000"
          MERGE_REQUIRED_APPROVALS: "0"
          UPDATE_LABELS: ""
          UPDATE_METHOD: "rebase"
          PULL_REQUEST: "1234"
          MAX_PR_COUNT: "25"

Supported Events

Automerge can be configured to run for these events:

check_run
check_suite
issue_comment
pull_request_review
pull_request_target
pull_request
push
repository_dispatch
schedule
status
workflow_dispatch
workflow_run

For more information on when these occur, see the Github documentation on events that trigger workflows and their payloads.

Outputs

The action will provide two outputs:

mergeResult - The result from the action run, one of skipped, not_ready, author_filtered, merge_failed, merged
pullRequestNumber - The pull request number (or 0, if no pull request was affected)

Please note:

When there are multiple pull requests affected, only the first one will be available in the output
To access these outputs, your workflow configuration must define an id for the automerge-action step
Unless a personal access token is used, this action will not trigger other actions, see Limitations

Example usage:

    steps:
      - id: automerge
        name: automerge
        uses: "pascalgn/automerge-action@v0.15.6"
        env:
          GITHUB_TOKEN: "${{ secrets.GITHUB_TOKEN }}"
      - name: feedback
        if: ${{ steps.automerge.outputs.mergeResult == 'merged' }}
        run: |
          echo "Pull request ${{ steps.automerge.outputs.pullRequestNumber }} merged!"

Limitations

When a pull request is merged by this action, the merge will not trigger other GitHub workflows. Similarly, when another GitHub workflow creates a pull request, this action will not be triggered. This is because an action in a workflow run can't trigger a new workflow run. However, the workflow_run event is triggered as expected.
When using a personal access token (PAT) to work around the above limitation, note that when the user issuing the PAT is an administrator and branch restrictions do not include administrators, pull requests may be merged even if they are not mergeable for non-administrators (see #65).
Currently, there is no way to trigger workflows when the pull request branch becomes out of date with the base branch. There is a request in the GitHub community forum.

Debugging

To run the action with full debug logging, update your workflow file as follows:

      - name: automerge
        uses: pascalgn/automerge-action@...
        env:
          GITHUB_TOKEN: "${{ secrets.GITHUB_TOKEN }}"
          LOG: "TRACE"  # or "DEBUG"

If you need to further debug the action, you can run it locally.

You will need a personal access token.

Then clone this repository, create a file .env in the repository, such as:

GITHUB_TOKEN="123abc..."
URL="https://github.com/pascalgn/repository-name/pull/123"

Install dependencies with yarn, and finally run yarn it (or npm run it).

License

MIT