Simulate a tfs style changeset in the enterprise version of github

Question

I have three environments; dev, test and staging/prod. In our previous model of using Team Foundation Server, we would have three branches of code that matched up to each of these three environments.

Developers would work locally and when they had their code complete, they'd check it into the dev branch. When checking in, TFS automatically creates something called a changeset. This check-in would kick off a build of the files into code which then gets deployed to the dev environment.

When a developer was happy with their code in dev, they'd merge just their changeset into the test branch. They'd pull up a complete list of all of the available changesets that dhad not been merged into test, they'd select theirs and check those into the test branch. Again, this would kick off a build and the output files would get deployed to test.

Once QA was happy with the changes, the dev would merge this changeset into the prod branch. Kicking off a build and the files would be deployed to the staging area. The developer and QA would them promote these files to prod.

All of would allow multiple developers to work on the same files using this changeset mentality. When a specific changeset (or set of changesets) was merged into another environment, only those changes would get merged.

In my relatively new exposure to git, I cannot seem to find a way to select specific "pull requests" (which I assume is similar to a TFS changeset) from one branch to another branch. When I try to make a pull request from one branch to another branch, it wants to pull in not only my pull request, but every other pull request made in the lower branch by other developers too. What is the magic way to make this happen?

Note: Unfortunately we don't have the notion of a "release". We have five scrum teams working on one website with over 200 pages. Each scrum team has their own sprints and can release multiple scrum stories during their sprint. We have internally only one DEV environment, and one TEST environment and one PROD environment. Not only are our environments used by these five scrum teams, but these DEV/TEST/PROD sites are is also used by various other teams for integration efforts with applications we sell and also for customer account management and purchasing. We cannot change that infrastructure.

Note: this is not for a discussion as to if this "changeset" methodology is correct or proper. This is a question of how to achieve this behavior in github/git.

Note: we are a set of scrum-based agile teams. We work from stories. As many as 60 stories can be actively in development at any one time with our large team of 25+ developers. When one story is ready for prod, we promote it to the prod environment as an atomic unit. So think of a changeset as a story.

Answer 1

I have two thoughts:

1. Don't do it this way. Instead, you should look to git-flow. http://danielkummer.github.io/git-flow-cheatsheet/ and http://nvie.com/posts/a-successful-git-branching-model/ are good explanations. At it's core, git-flow is a naming convention for branches, so it's really not tied to git at all. In essence, you have feature branches that each developer or dev team works on. Once they complete a feature, they merge into develop. develop is "done features" -- not "done done" but rather "feature complete." When we deem it time to release, we fork to a new release/someversion branch (name to match the release name), and then work with QA to harden the release. Commits on the release/someversion branch are only bug fixes. Once it's good enough to deploy, we fast-forward the master branch up to the release branch as we push it into production. master then represents what's in production. As we deploy, we also merge release/someversion into develop so the bug fixes get into the mainline of development. The project manager / product owner can then think of the develop branch as "the latest," and developers can continue on their feature branches until they're feature complete. (Hint, make features small -- like an hour or a day. Features are not releases.)

So why is this better than the way you were doing it? If the feature is done, ready enough for QA to start banging on it, it's done enough to be part of the next release. Picking and choosing features around each other will lead you into very subtle and unpredictable bugs. Since you're re-merging at each step, you have the possibility that you'll merge incorrectly, creating a bug. You're also now creating unique product with each step, so you could get to production with a completely different set of features than you vetted in dev and test. (Will this do bad things? Ask your pharmacist if these drugs interact when taken together.)

Git-flow works great for cadences where you have well coordinated, infrequent, larger releases. As you get closer to continuous delivery, this ceremony will get in your way. At that point, you may choose to flip to GitHub flow or a similar lighter-weight naming convention.

2. If you're really, really, really (see the above "you shouldn't do it this way" comment) convinced you should do it this way, first, go convince a rubber duck and hopefully you will have talked yourself out of it. If you're still really, really convinced you need to do this, you'll frequently need to squash your commits together creating one large commit for the entire feature, then cherry pick the changeset between the branches.

There's a few disadvantages to this "squash and cherry-pick" approach. 1. You lose history. Since you're squashing the history together, you have to now keep features in very contained bundles, and frequently edit the bundle as a whole. One of the primary premises of source control is you get an audit history -- both to roll back to if something goes wrong, and to reference when you need to learn why something works this way or who to talk to about it. (See "git blame".) When you squash, you intentionally remove that learning tool. 2. You're playing features into place in different orders. So you're frequently doing merges. What makes git so awesome is merging is easy. What makes git merging easy is you do it in small pieces. This methodology of squashing everything associated with this feature into one huge commit and cherry-picking it between branches means you're doing very large merges ... which means it will be hard.

Yeah, I know you're quite enamored with the way it's always been, and you really don't want someone telling you your baby is ugly. Sorry. Your baby was ugly. On the bright side, it doesn't need to be. Git flow is awesome, and can definitely facilitate the velocity your team needs.

Answer 2

You previous behavior was dysfunctional. Although not unusual: http://nakedalm.com/avoid-pick-n-mix-branching-anti-pattern/

In Git you most likely want to do two things. The first is to follow Git Flow: http://nvie.com/posts/a-successful-git-branching-model/

Once you have this you can look at creating a deployment pipeline for binaries, not for source. You should do a build from MASTER and that build goes through your environments. Happy to discuss here and offline.