git-flux - A git branching model for Infrastructure as code workflows

Overview

What? git-flux is a set of custom git commands implementing a workflow tailored to managing "infrastructure as code", or configuration management systems, such as Puppet or Chef and based heavily on git-flow.

It is intended to be used in conjunction with a setup similar to that described in this blog article from puppetlabs where multiple, permanent, branches are aligned to different environments.

For example you may have a puppet.git repository with long-living branches like 'development', 'testing', and 'production' branches corresponding to these environments in your infrastructure. This tool helps you safely control the movement of changes through each environment as testing or sign-off is completed.

Why not use git-flow? Originally we wanted to but as we started discussing what the workflow would look like we realized it was not a good fit for this particular problem. For example, consider a scenario with two people making changes to Puppet modules. Both changes could be completely independent of each other and the intention is for both to move through the environments (dev -> test -> prod) at their own pace. Using git-flow, person A would create a feature branch based on develop, make their changes and push back to the develop branch. Person B would then branch from develop and work on his changes. This branch would contain Person A's changes too. If Person B's change is ready to move to the test environment first, then he will bring along Person A's change even though that change is not ready to be promoted to the test environment (or prod!)

This leads to the first rule of this workflow: we always create feature branches from the production branch because any code on the production branch is assumed to have passed through all other environments and should not have any work in progress on it.

Also, this tool tries to keep the types of branches to a minimum. There are currently only two branch 'types': feature and environment. Feature branches are short-lived branches that are created for making changes to the codebase. Environment branches are long-lived branches that correspond to a live deployment. Feature branches are merged into environment branches.

See the Typical Workflow section below for more details on how changes move through the workflow.

Installation

$ git clone git://github.com/joemiller/git-flux.git
$ cd git-flux
$ sh install.sh install

To uninstall:

$ sh install.sh uninstall

Getting started

Preparing a repo (one-time task)

Prepare a repository for git flux by running git flux init which will create the all important production environment branch. This branch is used to create all other environment and feature branches. It only needs to be run once.

If this is an existing git repo, the master branch will be cloned to create the production branch. If it's a new repo, a branch will be created.

$ git flux init

Summary of actions:
    - Created environment branch: 'environment/production'
    - You are now on branch 'environment/production'

Next steps:
    - Create more environment branches with 'git flux env new <environment_name>
    - Setup a remote repository named 'origin'.
    - Publish your environment branches to remote with 'git flux publish <environment_name>'

Create other environment branches

Next, create additional environment branches. All environment branches are based off of the production environment branch.

$ git flux env new development
Switched to a new branch 'environment/testing'

Summary of actions:
- A new environment branch 'testing' was created, based on 'environment/production'.
- You are now on branch 'environment/testing'.

Publish environment branches to remote server

To publish environment branches to remote 'origin' server:

$ git flux publish development

Update local branches

git-flux has a command that is very similar to git-up which provides a convenient way to update all local branches with any changes on the remote server.

Unlike git-up, a local tracking branch does not need to exist first. Thus, git flux up is a great way to pull down all remote feature and environment branches after the first git clone from remote.

$ git flux up

Updating Feature branches:
  TKT-512_adding_cool_stuff   up to date
  some_new-feature            up to date

Updating Environment branches:
  production   up to date
* development  up to date
  testing      up to date

Typical workflow

After a repo has been prepared by running git flux init and your environment branches have been created and published, the typical workflow for changes might look like this:

1. Create a feature branch based on the production environment branch.
2. Make edits, commit, push.
3. Merge the feature branch into the development environment branch.
4. Test the changes, repeat steps 2 and 3 if necessary.
5. Merge the feature branch into the testing environment branch.
6. Do more testing.
7. Merge the feature branch into the production environment branch.
8. Done.

Create a new feature branch.

$ git flux feature new TKT-512_adding_cool_stuff
<edit files, `git commit`, then..>
$ git flux publish TKT-512_adding_cool_stuff

It is not required to publish feature branches but it can be very useful for the rest of the team to be able to see your work in progress, or they can finish merging it into environment branches if you get hit by a bus.

Merge a feature branch into an environment branch:

$ git flux feature merge TKT-512_adding_cool_stuff development

Publish/push updated environment branch to remote server:

After merging a feature branch into an environment branch, the next step will be to push your changes to the remote server (if you're ready):

$ git flux publish development

After testing is completed in the development environment, the feature branch can be merged to other environment branches. Use the git flux feature status command to see which feature branches are awaiting merging into environment branches.

Other commands

List feature branches waiting to be merged into environment branches

It is possible to get a list of feature branches that have not yet been merged into environment branches. This feature is still experimental.

$ git flux feature status

Unmerged feature branches for environment 'development':

Unmerged feature branches for environment 'production':
  TKT-512_adding_cool_stuff

Unmerged feature branches for environment 'testing':
  TKT-512_adding_cool_stuff

List branches

List feature branches by using the feature command with no arguments or with the list argument

$ git flux feature
  TKT-512_adding_cool_stuff
* some_new-feature

List environment branches by using the env command with no arguments or with the list argument:

$ git flux env
  development
* production
  testing

Switch (checkout) to a feature or environment branch

git-flux provides a shortcut for switching to an environment or feature branch without providing the full prefix. You may need to run git flux up first if the branch exists on the remote server but not locally.

$ git flux checkout production

Is equivalent to:

$ git checkout environment/production

Support

Open a new issue on github.

Contributing

Fork the repository. Then, run:

git flow init -d
git flow feature start <new_feature>

Then, do work and commit your changes. Publish your feature to github and open a pull request to your feature branch.

git flow feature publish <new_feature>

License

Portions of this code are taken from git-flow. git-flow is Copyright Vincent Driessen. See gitflux-common for the git-flow license.

Copyright 2012 Joe Miller. All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice,
   this list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions and the following disclaimer in the
   documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY JOE MILLER ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JOE MILLER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

The views and conclusions contained in the software and documentation are those of the authors and should not be interpreted as representing official policies, either expressed or implied, of Joe Miller.