GitHub Action: Dependabot Auto Merge

Automatically merge Dependabot PRs when version comparison is within range.

Note: Dependabot will wait until all your status checks pass before merging. This is a function of Dependabot itself, and not this Action.

Usage

name: auto-merge

on:
  pull_request_target:

jobs:
  auto-merge:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - uses: ahmadnassri/action-dependabot-auto-merge@v2
        with:
          target: minor
          github-token: ${{ secrets.mytoken }}

The action will only merge PRs whose checks (CI/CD) pass.

Examples

Minimal setup:

steps:
  - uses: ahmadnassri/action-dependabot-auto-merge@v2
    with:
      github-token: ${{ secrets.mytoken }}

Only merge if the changed dependency version is a patch (default behavior):

steps:
  - uses: ahmadnassri/action-dependabot-auto-merge@v2
    with:
      target: patch
      github-token: ${{ secrets.mytoken }}

Only merge if the changed dependency version is a minor:

steps:
  - uses: ahmadnassri/action-dependabot-auto-merge@v2
    with:
      target: minor
      github-token: ${{ secrets.mytoken }}

Using a configuration file:

.github/workflows/auto-merge.yml

steps:
  - uses: actions/checkout@v2
  - uses: ahmadnassri/action-dependabot-auto-merge@v2
    with:
      github-token: ${{ secrets.mytoken }}

.github/auto-merge.yml

- match:
    dependency_type: all
    update_type: "semver:minor" # includes patch updates!

Inputs

input	required	default	description
github-token	✔	github.token	The GitHub token used to merge the pull-request
config	✔	.github/auto-merge.yml	Path to configuration file (relative to root)
target	❌	patch	The version comparison target (major, minor, patch)
command	❌	merge	The command to pass to Dependabot
approve	❌	true	Auto-approve pull-requests

Token Scope

The GitHub token is a Personal Access Token with the following scopes:

• repo for private repositories
• public_repo for public repositories

The token MUST be created from a user with push permission to the repository.

ℹ see reference for user owned repos and for org owned repos

Configuration file syntax

Using the configuration file (specified with config input), you have the option to provide a more fine-grained configuration. The following example configuration file merges

• minor updates for aws-sdk
• minor development dependency updates
• patch production dependency updates
• minor security-critical production dependency updates

- match:
    dependency_name: aws-sdk
    update_type: semver:minor

- match:
    dependency_type: development
    update_type: semver:minor # includes patch updates!

- match:
    dependency_type: production
    update_type: security:minor # includes patch updates!

- match:
    dependency_type: production
    update_type: semver:patch

Match Properties

property	required	supported values
dependency_name	❌	full name of dependency, or a regex string
dependency_type	❌	all, production, development
update_type	✔	all, security:*, semver:*

update_type can specify security match or semver match with the syntax: ${type}:${match}, e.g.

• security:patch
  SemVer patch update that fixes a known security vulnerability

• semver:patch
  SemVer patch update, e.g. > 1.x && 1.0.1 to 1.0.3

• semver:minor
  SemVer minor update, e.g. > 1.x && 2.1.4 to 2.3.1

To allow prereleases, the corresponding prepatch, preminor and premajor types are also supported

Defaults

By default, if no configuration file is present in the repo, the action will assume the following:

- match:
    dependency_type: all
    update_type: semver:${TARGET}

Where $TARGET is the target value from the action Inputs

The syntax is based on the legacy dependaBot v1 config format. However, in_range is not supported yet.

Exceptions and Edge Cases

1. Parsing of version ranges is not currently supported

Update stone requirement from ==1.* to ==3.*
requirements: update sphinx-autodoc-typehints requirement from <=1.11.0 to <1.12.0
Update rake requirement from ~> 10.4 to ~> 13.0

2. Parsing of non semver numbering is not currently supported

Bump actions/cache from v2.0 to v2.1.2
chore(deps): bump docker/build-push-action from v1 to v2

3. Sometimes Dependabot does not include the "from" version, so version comparison logic is impossible:

Update actions/setup-python requirement to v2.1.4
Update actions/cache requirement to v2.1.2

if your config is anything other than update_type: all, or update_type: semver:all the action will fallback to manual merge, since there is no way to compare version ranges for merging.

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Author: Ahmad Nassri • Twitter: @AhmadNassri