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- Workflow for Maintainers

# Workflow for Maintainers

This page is for maintainers — those of us who merge our own or other peoples’ changes into the upstream repository.

Being as how you’re a maintainer, you are completely on top of the basic stuff in Workflow for Developers.

## Integrating changes via the web interface (recommended)

Whenever possible, merge pull requests automatically via the pull request manager on GitHub. Merging should only be done manually if there is a really good reason to do this!

Make sure that pull requests do not contain a messy history with merges, etc. If this is the case, then follow the manual instructions, and make sure the fork is rebased to tidy the history before committing.

## Integrating changes manually

First, check out the `astropy` repository. The instructions in Overview add a remote that has read-only access to the upstream repo. Being a maintainer, you’ve got read-write access.

It’s good to have your upstream remote have a scary name, to remind you that it’s a read-write remote:

    git remote add upstream-rw git@github.com:astropy/astropy.git
    git fetch upstream-rw

Let’s say you have some changes that need to go into trunk (`upstream-rw/master`).

The changes are in some branch that you are currently on. For example, you are looking at someone’s changes like this:

    git remote add someone git://github.com/someone/astropy.git
    git fetch someone
    git branch cool-feature --track someone/cool-feature
    git checkout cool-feature

So now you are on the branch with the changes to be incorporated upstream. The rest of this section assumes you are on this branch.

### A few commits

If there are only a few commits, consider rebasing to upstream:

    # Fetch upstream changes
    git fetch upstream-rw

    # Rebase
    git rebase upstream-rw/master

Remember that, if you do a rebase, and push that, you’ll have to close any github pull requests manually, because github will not be able to detect the changes have already been merged.

### A long series of commits

If there are a longer series of related commits, consider a merge instead:

    git fetch upstream-rw
    git merge --no-ff upstream-rw/master

The merge will be detected by github, and should close any related pull requests automatically.

Note the `--no-ff` above. This forces git to make a merge commit, rather than doing a fast-forward, so that these set of commits branch off trunk then rejoin the main history with a merge, rather than appearing to have been made directly on top of trunk.

### Check the history

Now, in either case, you should check that the history is sensible and you have the right commits:

    git log --oneline --graph
    git log -p upstream-rw/master..

The first line above just shows the history in a compact way, with a text representation of the history graph. The second line shows the log of commits excluding those that can be reached from trunk (`upstream-rw/master`), and including those that can be reached from current HEAD (implied with the `..` at the end). So, it shows the commits unique to this branch compared to trunk. The `-p` option shows the diff for these commits in patch form.

### Push to trunk

    git push upstream-rw my-new-feature:master

This pushes the `my-new-feature` branch in this repository to the `master` branch in the `upstream-rw` repository.

## Using Milestones and Labels

These guidelines are adapted from similar guidelines followed by IPython:

- 100% of confirmed issues and new features should have a milestone
- Only the following criteria should result in an issue being closed without a milestone:
  - Not actually an issue (user error, etc.)
  - Duplicate of an existing issue
  - A pull request superceded by a new pull request providing an alternate implementation
- Open issues should only lack a milestone if:
  - More clarification is required
  - Which milestone it belongs in requires some discussion
- Corollary: When an issue is closed without a milestone that means that the issue will not be fixed, or that it was not a real issue at all.
- In general there should be the following open milestones:
  - The next bug fix releases for any still-supported version lines; for example if 0.4 is in development and 0.2.x and 0.3.x are still supported there should be milestones for the next 0.2.x and 0.3.x releases.
  - The next X.Y release, ie. the next minor release; this is generally the next release that all development in master is aimed toward.
  - The next X.Y release +1; for example if 0.3 is the next release, there should also be a milestone for 0.4 for issues that are important, but that we know won’t be resolved in the next release.
  - Future–this is for all issues that require attention at some point but for which no immediate solution is in sight.
- Bug fix release milestones should only be used for deferring issues that won’t be fixed in the next minor release, or for issues is previous releases that no longer apply to the mainline.
- When in doubt about which milestone to use for an issue, use the next minor release–it can always be moved once it’s been more closely reviewed prior to release.
- Active milestones associated with a specific release (eg. v0.3.0) should contain at least one issue with the `release` label representing the actual task for releasing that version (this also works around the GitHub annoyance that milestones without any open issues are automatically closed).
- Issues that require fixing in the mainline, but that also are confirmed to apply to supported stable version lines should be marked with one or more `backport-*` labels for each v0.X.Y branch that has the issue.
  - In some cases it may require extra work beyond a simple merge to port bug fixes to older lines of development; if such additional work is required it is not a bad idea to open a “Backport #nnn to v0.X.Y” issue in the appropriate v0.X.Y milestone.

## Updating and Maintaining the Changelog

The Astropy “changelog” is kept in the file `CHANGES.rst` at the root of the repository. As the filename extension suggests this is a reStructured Text file. The purpose of this file is to give a technical, but still user (and developer) oriented overview of what changes were made to Astropy between each public release. The idea is that it’s a little more to the point and easier to follow than trying to read through full git log. It lists all new features added between versions, so that a user can easily find out from reading the changelog when a feature was added. Likewise it lists any features or APIs that were changed (and how they were changed) or removed. It also lists all bug fixes. Affiliated packages are encouraged to maintain a similar changelog.

### Adding to the changelog

There are two approaches one may take to adding a new entry to the changelog, each with certain pros and cons. Before describing the two specific approaches it should be said that all additions to the changelog should be made first in the ‘master’ branch. This is because every release of Astropy includes a copy of the changelog, and it should list all the changes in every prior version of Astropy. For example, when Astropy v0.3.0 is released, in addition to the changes new to that version the changelog should have all the changes from every v0.2.x version (and earlier) released up to that point.

Two approaches for including a changelog entry for a new feature or bug fix are:

- Include the changelog update in the same pull request as the change. That is, assuming this change is being made in a pull request it can include an accurate changelog update along with it.

  Pro: An addition to the changelog is just like any other documentation update, and should be part of any atomic change to the software. It can be pulled into master along with the rest of the change.

  Con: If many pull requests also include changelog updates, they can quickly conflict with each other and require rebasing. This is not difficult to resolve if the only conflict is in the changelog, but it can still be trouble especially for new contributors.

- Add to the changelog after a change has been merged to master, whether by pull request or otherwise.

  Pro: Largely escapes the merge conflict issue.

  Cons: Isn’t included “atomically” in the merge commit, making it more difficult to keep track of for backporting. Requires new contributors to either make a second pull request or have a developer with push access to the main repository make the commit.

The first approach is probably preferable, especially for core contributors. But the latter approach is acceptable as well.

### Changelog format

The exact formatting of the changelog content is a bit loose for now (though it might become stricter if we want to develop more tools around the changelog). The format can be mostly inferred by looking at previous verisons. Each release gets its own heading (using the `-` heading marker) with the version and release date. Releases still under development have `(unreleased)` as there is no release date yet.

There are generally up to three subheadings (using the `^` marker): “New Features”, “API Changes”, “Bug Fixes”, and “Other Changes and Additions”. The latter is mostly a catch-all for miscellaneous changes, though there’s no reason not to make up additional sub-headings if it seems appropriate.

Under each sub-heading, changes are typically grouped according to which sub-package they pertain to. Changes that apply to more than one sub-package or that only apply to support modules like `logging` or `utils` may go under a “Misc” group.

The actual texts of the changelog entries are typically just one to three sentences–they should be easy to glance over. Most entires end with a reference to an issue/pull request number in square brackets.

A single changelog entry may also reference multiple small changes. For example:

    - Minor documentation fixes and restructuring.
      [#935, #967, #978, #1004, #1028, #1047]

Beyond that, the best advice for updating the changelog is just to look at existing entries for previous releases and copy the format.