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GitHub Workflow#

This guide assumes you have already cloned the upstream repo to your system via git clone, or via go get github.com/k0sproject/k0s.

Fork The Project#

  1. Go to http://github.com/k0sproject/k0s
  2. On the top, right-hand side, click on "fork" and select your username for the fork destination.

Adding the Forked Remote#

export GITHUB_USER={ your github username }

cd $WORKDIR/k0s
git remote add $GITHUB_USER git@github.com:${GITHUB_USER}/k0s.git

# Prevent push to Upstream
git remote set-url --push origin no_push

# Set your fork remote as a default push target
git push --set-upstream $GITHUB_USER main

Your remotes should look something like this:

git remote -v

origin  https://github.com/k0sproject/k0s (fetch)
origin  no_push (push)
my_fork git@github.com:{ github_username }/k0s.git (fetch)
my_fork git@github.com:{ github_username }/k0s.git (push)

Create & Rebase Your Feature Branch#

Create a feature branch and switch to it:

git checkout -b my_feature_branch

Rebase your branch:

git fetch origin && \
  git rebase origin/main

Current branch my_feature_branch is up to date.

Please don't use git pull instead of the above fetch / rebase. git pull does a merge, which leaves merge commits. These make the commit history messy and violate the principle that commits ought to be individually understandable and useful.

Commit & Push#

Each commit should serve one purpose. Keep unrelated changes, such as refactorings or cleanups you make along the way, in separate commits. Commit and sign your changes:

git commit --signoff

Commit messages should have a short, capitalized subject without trailing period as first line. After the subject a blank line and then a longer description that explains why the change was made, unless it is obvious.

Use imperative mood in the commit message.

For example:

Summarize changes in around 50 characters or less

More detailed explanatory text, if necessary. Wrap it to about 72
characters or so. In some contexts, the first line is treated as the
subject of the commit and the rest of the text as the body. The
blank line separating the summary from the body is critical (unless
you omit the body entirely); various tools like `log`, `shortlog`
and `rebase` can get confused if you run the two together.

Explain the problem that this commit is solving. Focus on why you
are making this change as opposed to how (the code explains that).
Are there side effects or other unintuitive consequences of this
change? Here's the place to explain them.

Further paragraphs come after blank lines.

 - Bullet points are okay, too

 - Typically a hyphen or asterisk is used for the bullet, preceded
   by a single space, with blank lines in between.

Put references to earlier commits and other relevant material at the
bottom, like this:

Fixes: a50271db8 ("Implement k0s feature gates")
See: f9773809e ("Encapsulate debug flag handling")
See: https://kubernetes.io/docs/reference/command-line-tools-reference/feature-gates/

Signed-off-by: Name Lastname <user@example.com>

The commit message is read by whoever looks at this change years from now via git blame or git log. Write it for them:

  • State what was wrong, what the change does, and why. If the change fixes a regression, say what the effect was in released versions.
  • Mention non-obvious constraints the code depends on, such as ordering, timing, or compatibility with data written by earlier versions. These are the things a future reader can't reconstruct from the diff.
  • If you remove dead code or do unrelated cleanup while you're there, say so. Don't present it as part of the fix.
  • Leave out how you found the bug, what you tried, what the change does not fix, and anything addressed to the reviewer. That material belongs in the pull request description or the discussion.
  • Don't reference source file paths unless it aids understanding. The diff already lists them.

Use Fixes: for the commit that introduced the problem this change corrects, if it can be identified. The issue a change resolves is referenced from the pull request description instead, where GitHub's closing keywords act on it. Use See: for anything else that helps to understand the change: related commits, external documentation, specifications, and the like.

When referencing other commits, use the abbreviated hash, e.g. as printed by git log --oneline, along with the subject line: a50271db8 ("Implement k0s feature gates"). That way, the reference is meaningful in git log, whether or not the hash resolves. In general, prefer what works locally over what only works on GitHub.

Note that GitHub adds a timeline event to an issue or pull request whenever a commit referencing it is pushed to any public repository, including your own fork. Since a rebase creates new commits, every force-push repeats those events, and frequent rebases leave a trail of identical entries in the timeline. That's another reason to reference issues and pull requests from the pull request description rather than from commit messages.

When ready, push your changes to your fork's repository:

git push --set-upstream my_fork my_feature_branch

You can go back and edit/build/test some more, then commit --amend in a few cycles.

After review rounds, fold any fixup commits into the commits they belong to and rewrite the messages so that each commit describes its final change, not its history. Commits titled "Address review comments" are fine during reviews, but clutter the history once merged. See Squashing Commits for how to do that.

Open a Pull Request#

See GitHub's docs on how to create a pull request from a fork.

Just as with commits, a pull request should serve one purpose. While a pull request may have a broader goal than a single commit, each commit within it should be a self-contained step toward that goal. Keep unrelated changes in separate pull requests. Focused pull requests are easier to understand, review, and manage. Contested but unrelated parts of a pull request might prevent other acceptable parts from being merged, and backports become more manageable when they don't have to be untangled from unrelated changes first.

The purpose of the pull request description is to facilitate discussion. It should include the context, the alternatives considered, what was verified and how it was verified, and what the change deliberately leaves out. It must not contradict the commit messages. When you rewrite commits after a review round, re-read the description and update it, too.

Get a code review#

Once your pull request has been opened it will be assigned to one or more reviewers, and will go through a series of smoke tests.

Commit changes made in response to review comments should be added to the same branch on your fork.

Very small PRs are easy to review. Very large PRs are very difficult to review.

Squashing Commits#

Commits on your branch should represent meaningful milestones or units of work. Small commits that contain typo fixes, rebases, review feedbacks, etc should be squashed.

To do that, it's best to perform an interactive rebase:

Example#

Rebase your feature branch against upstream main branch:

git rebase -i origin/main

If your PR has 3 commits, output would be similar to this:

pick f7f3f6d Changed some code
pick 310154e fixed some typos
pick a5f4a0d made some review changes

# Rebase 710f0f8..a5f4a0d onto 710f0f8
#
# Commands:
# p, pick <commit> = use commit
# r, reword <commit> = use commit, but edit the commit message
# e, edit <commit> = use commit, but stop for amending
# s, squash <commit> = use commit, but meld into previous commit
# f, fixup <commit> = like "squash", but discard this commit's log message
# x, exec <command> = run command (the rest of the line) using shell
# b, break = stop here (continue rebase later with 'git rebase --continue')
# d, drop <commit> = remove commit
# l, label <label> = label current HEAD with a name
# t, reset <label> = reset HEAD to a label
# m, merge [-C <commit> | -c <commit>] <label> [# <oneline>]
# .       create a merge commit using the original merge commit's
# .       message (or the oneline, if no original merge commit was
# .       specified). Use -c <commit> to reword the commit message.
#
# These lines can be re-ordered; they are executed from top to bottom.
#
# However, if you remove everything, the rebase will be aborted.
#
# Note that empty commits are commented out

Use a command line text editor to change the word pick to f of fixup for the commits you want to squash, then save your changes and continue the rebase:

Per the output above, you can see that:

fixup <commit> = like "squash", but discard this commit's log message

Which means that when rebased, the commit message "fixed some typos" will be removed, and squashed with the parent commit.

Push Your Final Changes#

Once done, you can push the final commits to your branch:

git push --force

You can run multiple iteration of rebase/push -f, if needed.