In my work at Rackspace with the FDaAT git features heavily. My group's rate of development is fairly rapid: it is not atypical for our projects to receive multiple pull requests in a day, in addition to the work I'm doing. How I keep my changes separated from an evolving codebase without falling behind involves a particular bit of bookkeeping.
Before I explain what that is, I should note that our projects follow a fairly typical canonical master repository / development fork model. Take FireEngine as an example. We've got the
fdaat/fire_engine canonical repo into which all code is pull-request merged and from which deployments are made; developer repositories get commits to feature branches and these feature branches become pull-requests against
fdaat/fire_engine's master branch. (If pull requests are a new thing to you, here's how github describes them. Note they use the term 'fork & pull' for the model I'm discussing.)
When I issue a pull request I want github to be able to merge my commits automatically. For this to happen, especially if my feature branch lives for more than a day, I have to integrate the commits from the canonical master branch that went up after I made my initial branch.
This is what I do.
I work out of a local development repository.
In a development repository anything goes: force pushes, screwy rebases, erasure of commits you subsequently think better of. No one is inconvenienced if a development repository sees bad code or bad actions. That's why whenever I to join in on a new project I make a remote fork of the canonical repository and clone my fork locally. Like so:
git clone email@example.com:blt/fire_engine.git fire_engine
The master of local fire_engine tracks that of
I track canonical master in a read-only branch.
I call this branch upstream and create it like so:
$ git remote add upstream git://github.rackspace.com/fdaat/fire_engine.git $ git fetch --all $ git checkout -b upstream upstream/master
Now local upstream tracks canonical master and I can get any new commits into canonical from this branch.
Why read-only? Accidents happen.
Before I start a feature branch, rebase from upstream.
It's more simple to sync with upstream before beginning a feature than it is to do so after some development effort has passed. I never make commits directly into local master, preferring it to be an exact replica of canonical master. (Why? Consider the difficulty of committing to local master if you're working two or more features at a time.) Here's how I sync with upstream:
$ git checkout upstream && git pull $ git checkout master && git rebase upstream
At this point local master is exactly canonical master. The branch off this is what you'd expect:
$ git checkout -b super_new_feature
Before wrapping up with a pull request, sync with upstream again.
super_new_feature has everything you'd want, but just before making a pull-request, I sync with upstream again to be sure there will be no merge conflicts.
$ git checkout upstream && git pull $ git checkout super_new_feature && git rebase upstream
The difference here that I've synced into
super_new_feature and not master. I skip master, and so my local master often lags behind until it's time to make a new feature branch.
That's that. After a successful sync the feature branch is ready to submit as a pull request that'll merge successfully. It's a simple approach that works out well in practice.