backport๐Ÿ”—

It is common for software to have (some of) their major versions maintained over an extended period. Developers usually create stable branches that are maintained for a while by cherry-picking patches from the development branch.

This process is called backporting as it implies that bug fixes merged into the development branch are ported back to the stable branch(es). The stable branch can then be used to release a new minor version of the software, fixing some of its bugs.

As this process of backporting patches can be tedious, Mergify automates this mechanism to save developers' time and ease their duty.

The backport action copies the pull request into another branch once the pull request has been merged.

Once the backporting pull request is closed or merged, Mergify will automatically delete the backport head branch that it created.

You can also trigger backports using the backport command.

Options๐Ÿ”—

Key Name

Value Type

Default

Value Description

branches

list of string

[]

The list of branches the pull request should be copied to.

regexes

list of string

[]

The list of regexes to find branches the pull request should be copied to.

ignore_conflicts

Boolean

true

Whether to create the pull requests even if they are conflicts when cherry-picking the commits.

bot_account

Template

Mergify can impersonate a GitHub user to backport a pull request. If no bot_account is set, Mergify backports the pull request itself.

labels

list of string

[]

The list of labels to add to the created pull requests.

label_conflicts

string

conflicts

The label to add to the created pull request if it has conflicts and ignore_conflicts is set to true.

assignees

list of Template

Users to assign the newly created pull request. As the type is Template, you could use, e.g., {{author}} to assign the pull request to its original author.

title

Template

{{ title }} (backport #{{ number }})

The pull request title.

body

Template

This is an automatic backport of pull request #{{number}} done by [Mergify](https://mergify.com).\n{{cherry_pick_error}}

The pull request body.

As the title and body are templates, you can leverage any pull request attributes to use as content, e.g. {{author}}. You can also use this additional variable:

  • {{ destination_branch }}: the name of destination branch.

  • {{ cherry_pick_error }}: the cherry pick error message if any (only available in body).

Examples๐Ÿ”—

๐Ÿ‘ฉโ€๐Ÿ”ง Using Labels to Backport Pull-Requests๐Ÿ”—

Copying pull requests to a maintenance branch is a common workflow. In order to elect a pull request to be backported, it's possible to use a label. With a rule such as the one below, you can trigger a backport as soon as the label is added and the pull request merged:

pull_request_rules:
  - name: backport patches to stable branch
    conditions:
      - base=main
      - label=backport-to-stable
    actions:
      backport:
        branches:
          - stable
        assignees:
          - "{{ author }}"