What does git-upstream do?¶
git-upstream provides new git subcommands to support rebasing of local-carried patches on top of upstream repositories. It provides commands to ease the use of git for who needs to integrate big upstream projects in their environment. The operations are performed using Git commands.
Currently git-upstream works best for projects that are maintained with Gerrit because the presence of Change-Ids allows for fully automated dropping of changes that appear upstream. Nevertheless, the code is quite modular and can be extended to use any part of commit message (e.g., other headers).
Git-upstream currently supports the following features
- Single upstream branch import
Your repository is tracking an upstream project and has local changes applied and no other branch is merged in. This can also be applied to tracking upstream packaging branches: e.g., ubuntu/master => ubuntu/saucy-proposed/nova + local packaging changes.
- Multi branch import (upstream branch + additional branches)
In this case, your project tracks an upstream repository, merges in an arbitrary number of branches and applies local carried changes.
Reviewing (w/ Gerrit) of all locally applied changes if desired. git-upstream creates an import branch in a manner that allows it to be fully re-reviewed or merged into master and pushed.
- Detailed logging
git-upstream can output to both console and log file simultaneously. Multiple log levels are supported, and these are managed separately for log file and console output. This means jobs run by Jenkins can save a detailed log file separately as an artefact while printing status information to the console if those running the jobs don’t wish to have the console spammed with the details.
- Dropping of changes that appear upstream
Compares Change-Id’s of changes applied since previous import with those that have appeared on the upstream branch since the last import point.
- Interactive mode
Once the list of changes to be re-applied has been determined (and those to be dropped have been pruned), the tool can open an editor (controlled by a user’s git editor settings) for users to review those changes to be made and allow them to perform further operations such as re-ordering, dropping of obsolete changes, and squashing.
- Dropping local changes
It’s always possible for local changes to be superseded by upstream changes, so when these are identified and marked as such, we should drop them.
This can also occur where a change was applied locally, modified when being upstreamed based on review feedback and the resulting differences were ported to the internal as well. While the original change will be automatically dropped, also useful to drop the additional ported changes automatically if possible, rather than have it cause conflicts.