r10k can use Git repositories to implement dynamic environments. You can create, update, and delete Puppet environments automatically as part of your normal Git workflow.
The core idea of dynamic environments is that you should be able to manage your Puppet modules in the same manner that you would manage any other code base. It builds on top of Git topic branch model.
One of the most prevalent ways of using Git relies on using topic branches. Whenever changes need to be made that need to be reviewed or tested before going live, they should be done in a different, short lived branch called a topic branch. Work can be freely done on a topic branch in isolation and when the work is completed it is merged into a "master" or "production" branch. This is very powerful because it allows any number of people to rapidly develop features in isolation and merge features in a single operation.
The dynamic environment model extends extends this git branching strategy to your live Puppet masters. It creates a mapping between Git branches and Puppet environments so that you can use the Git branching model and have that be seamlessly reflected in Puppet environments. This means that creating a new Git branch creates a new Puppet environment, updating a Git branch will update that environment, and deleting a Git branch will remove that environment.
r10k works by tracking the state of your git repositories and comparing them the the currently deployed environments. If there's a Git branch that doesn't have a corresponding Puppet environment then r10k will clone that branch into the appropriate directory. When Git branches are updated r10k will update the appropriate Puppet environment to the latest version. Finally if there are Puppet environments that don't have matching Git branches, r10k will assume that the branches for those environments were deleted and will remove those environments.
The following configuration options can be specified for Git based environment sources.
This setting specifies how Git branch names that cannot be cleanly mapped to Puppet environments will be handled.
Valid values:
- 'correct_and_warn': Non-word characters will be replaced with underscores and a warning will be emitted. (Default)
- 'correct': Non-word characters will silently be replaced with underscores.
- 'error': Branches with non-word characters will be ignored and an error will be emitted.