Backport CPython changes from main to maintenance branches.
Usage (from a cloned CPython directory)
cherry_picker [--pr-remote REMOTE] [--dry-run] [--config-path CONFIG-PATH] [--status] [--abort/--continue] [--push/--no-push] <commit_sha1> <branches>
- Setup Info
- Cherry-picking 🐍🍒⛏️
- Creating Pull Requests
- Running Tests
- Publishing to PyPI
- Local installation
This tool is used to backport CPython changes from main into one or more of the maintenance branches (3.6, 3.5, 2.7).
cherry_picker can be configured to backport other projects with similar workflow as CPython. See the configuration file options below for more details.
The maintenance branch names should contain some sort of version number (X.Y). For example: 3.6, 3.5, 2.7, stable-2.6, 2.5-lts, are all supported branch names.
It will prefix the commit message with the branch, e.g. [3.6], and then opens up the pull request page.
Tests are to be written using pytest.
Requires Python 3.6.
$ python3 -m venv venv $ source venv/bin/activate (venv) $ python -m pip install cherry_picker
The cherry picking script assumes that if an upstream remote is defined, then it should be used as the source of upstream changes and as the base for cherry-pick branches. Otherwise, origin is used for that purpose.
Verify that an upstream remote is set to the CPython repository:
$ git remote -v ... upstream https://github.com/python/cpython (fetch) upstream https://github.com/python/cpython (push)
If needed, create the upstream remote:
$ git remote add upstream https://github.com/python/cpython.git
By default, the PR branches used to submit pull requests back to the main repository are pushed to origin. If this is incorrect, then the correct remote will need be specified using the --pr-remote option (e.g. --pr-remote pr to use a remote named pr).
(Setup first! See prev section)
From the cloned CPython directory:
(venv) $ cherry_picker [--pr-remote REMOTE] [--dry-run] [--config-path CONFIG-PATH] [--abort/--continue] [--status] [--push/--no-push] <commit_sha1> <branches>
The commit sha1 for cherry-picking is the squashed commit that was merged to the main branch. On the merged pull request, scroll to the bottom of the page. Find the event that says something like:
<coredeveloper> merged commit <commit_sha1> into python:main <sometime> ago.
By following the link to <commit_sha1>, you will get the full commit hash. Use the full commit hash for cherry_picker.py.
--dry-run Dry Run Mode. Prints out the commands, but not executed. --pr-remote REMOTE Specify the git remote to push into. Default is 'origin'. --status Do `git status` in cpython directory.
--abort Abort current cherry-pick and clean up branch --continue Continue cherry-pick, push, and clean up branch --no-push Changes won't be pushed to remote --config-path Path to config file (`.cherry_picker.toml` from project root by default)
Configuration file example:
team = "aio-libs" repo = "aiohttp" check_sha = "f382b5ffc445e45a110734f5396728da7914aeb6" fix_commit_msg = false default_branch = "devel"
Available config options:
team github organization or individual nick, e.g "aio-libs" for https://github.com/aio-libs/aiohttp ("python" by default) repo github project name, e.g "aiohttp" for https://github.com/aio-libs/aiohttp ("cpython" by default) check_sha A long hash for any commit from the repo, e.g. a sha1 hash from the very first initial commit ("7f777ed95a19224294949e1b4ce56bbffcb1fe9f" by default) fix_commit_msg Replace # with GH- in cherry-picked commit message. It is the default behavior for CPython because of external Roundup bug tracker (https://bugs.python.org) behavior: #xxxx should point on issue xxxx but GH-xxxx points on pull-request xxxx. For projects using GitHub Issues, this option can be disabled. repo Project's default branch name, e.g "devel" for https://github.com/ansible/ansible ("main" by default)
To customize the tool for used by other project:
- Create a file called .cherry_picker.toml in the project’s root folder (alongside with .git folder).
- Add team, repo, fix_commit_msg, check_sha and default_branch config values as described above.
- Use git add .cherry_picker.toml / git commit to add the config into git.
- Add cherry_picker to development dependencies or install it by pip install cherry_picker
- Now everything is ready, use cherry_picker <commit_sha> <branch1> <branch2> for cherry-picking changes from <commit_sha> into maintenance branches. Branch name should contain at least major and minor version numbers and may have some prefix or suffix. Only the first version-like substring is matched when the version is extracted from branch name.
For example, to cherry-pick 6de2b7817f-some-commit-sha1-d064 into 3.5 and 3.6, run the following command from the cloned CPython directory:
(venv) $ cherry_picker 6de2b7817f-some-commit-sha1-d064 3.5 3.6
What this will do:
(venv) $ git fetch upstream (venv) $ git checkout -b backport-6de2b78-3.5 upstream/3.5 (venv) $ git cherry-pick -x 6de2b7817f-some-commit-sha1-d064 (venv) $ git push origin backport-6de2b78-3.5 (venv) $ git checkout main (venv) $ git branch -D backport-6de2b78-3.5 (venv) $ git checkout -b backport-6de2b78-3.6 upstream/3.6 (venv) $ git cherry-pick -x 6de2b7817f-some-commit-sha1-d064 (venv) $ git push origin backport-6de2b78-3.6 (venv) $ git checkout main (venv) $ git branch -D backport-6de2b78-3.6
In case of merge conflicts or errors, the following message will be displayed:
Failed to cherry-pick 554626ada769abf82a5dabe6966afa4265acb6a6 into 2.7 :frowning_face: ... Stopping here. To continue and resolve the conflict: $ cherry_picker --status # to find out which files need attention # Fix the conflict $ cherry_picker --status # should now say 'all conflict fixed' $ cherry_picker --continue To abort the cherry-pick and cleanup: $ cherry_picker --abort
Passing the --dry-run option will cause the script to print out all the steps it would execute without actually executing any of them. For example:
$ cherry_picker --dry-run --pr-remote pr 1e32a1be4a1705e34011770026cb64ada2d340b5 3.6 3.5 Dry run requested, listing expected command sequence fetching upstream ... dry_run: git fetch origin Now backporting '1e32a1be4a1705e34011770026cb64ada2d340b5' into '3.6' dry_run: git checkout -b backport-1e32a1b-3.6 origin/3.6 dry_run: git cherry-pick -x 1e32a1be4a1705e34011770026cb64ada2d340b5 dry_run: git push pr backport-1e32a1b-3.6 dry_run: Create new PR: https://github.com/python/cpython/compare/3.6...ncoghlan:backport-1e32a1b-3.6?expand=1 dry_run: git checkout main dry_run: git branch -D backport-1e32a1b-3.6 Now backporting '1e32a1be4a1705e34011770026cb64ada2d340b5' into '3.5' dry_run: git checkout -b backport-1e32a1b-3.5 origin/3.5 dry_run: git cherry-pick -x 1e32a1be4a1705e34011770026cb64ada2d340b5 dry_run: git push pr backport-1e32a1b-3.5 dry_run: Create new PR: https://github.com/python/cpython/compare/3.5...ncoghlan:backport-1e32a1b-3.5?expand=1 dry_run: git checkout main dry_run: git branch -D backport-1e32a1b-3.5
This will generate pull requests through a remote other than origin (e.g. pr)
This will do git status for the CPython directory.
Cancels the current cherry-pick and cleans up the cherry-pick branch.
Continues the current cherry-pick, commits, pushes the current branch to origin, opens the PR page, and cleans up the branch.
Changes won’t be pushed to remote. This allows you to test and make additional changes. Once you’re satisfied with local changes, use --continue to complete the backport, or --abort to cancel and clean up the branch. You can also cherry-pick additional commits, by:
$ git cherry-pick -x <commit_sha1>
Allows to override default config file path (<PROJ-ROOT>/.cherry_picker.toml) with a custom one. This allows cherry_picker to backport projects other than CPython.
When a cherry-pick was applied successfully, this script will open up a browser tab that points to the pull request creation page.
The url of the pull request page looks similar to the following:
Press the Create Pull Request button.
Bedevere will then remove the needs backport to ... label from the original pull request against main.
Install pytest: pip install -U pytest
$ pytest test.py
- Create a new release branch.
- Update the version info in __init__.py and readme.rst, dropping the .dev.
- Tag the branch as cherry-picker-vX.Y.Z.
- Support the main branch by default. (PR 23) To use a different default branch, please configure it in the .cherry-picker.toml file.
- Renamed cherry-picker’s own default branch to main.
- Implement state machine and storing reference to the config used at the beginning of the backport process using commit sha and a repo-local Git config. (PR #295).
- Validate the branch name to operate on with --continue and fail early if the branch could not have been created by cherry_picker. (PR #266).
- Bugfix: Allow --continue to support version branches that have dashes in them. This is a bugfix of the additional branch versioning schemes introduced in 1.2.0. (PR #265).
- Bugfix: Be explicit about the branch name on the remote to push the cherry pick to. This allows cherry_picker to work correctly when the user has a git push strategy other than the default configured. (PR #264).
- Add default_branch configuration item. The default is master, which is the default branch for CPython. It can be configured to other branches like, devel, or develop. The default branch is the branch cherry_picker will return to after backporting. (PR #254 and Issue #250).
- Support additional branch versioning schemes, such as something-X.Y, or X.Y-somethingelse. (PR #253 and Issue #251).
- Change the calls to subprocess to use lists instead of strings. This fixes the bug that affects users in Windows. (PR #238).
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