Git Worktree Buildkite Hooks
This changes the default checkout behaviour in the Buildkite agent bootstrap using hooks to use Git worktrees. It uses a single bare clone of each repository and creates a new worktree for each job. This means multiple agents on the same machine can share fetched repositories, multiple pipelines configured with the same repository can also share fetched repositories, and starting builds with pre-fetched repositories can be a little faster.
We also optimize the case where we have already fetched a git commit so that no remote transfer is necessary.
Usage
Copy the hooks directory contents into your Agent's hooks directory.
For example, on OS X with a homebrew-installed buildkite-agent:
# If you haven't installed the agent yet:
$ brew install buildkite/buildkite-agent/buildkite-agent
# Presuming you use the default locations:
$ cd /usr/local/etc/buildkite-agent/hooks
# Now download the hooks:
$ curl -sL https://github.com/sj26/git-worktree-buildkite-plugin/raw/master/hooks/pre-checkout > pre-checkout
$ curl -sL https://github.com/sj26/git-worktree-buildkite-plugin/raw/master/hooks/checkout > checkout
$ curl -sL https://github.com/sj26/git-worktree-buildkite-plugin/raw/master/hooks/post-command > post-command
$ curl -sL https://github.com/sj26/git-worktree-buildkite-plugin/raw/master/hooks/post-artifact > post-artifact
# And make sure they're executable:
$ chmod +x pre-checkout checkout post-command post-artifact
On Linux your hooks directory is likely /etc/buildkite-agent/hooks.
Caveats
Git worktrees are a fairly new feature. They don't always play well with git submodules