Introducing pre-commit hooks

I recently became aware of the open-source project: pre-commit, which is "A framework for managing and maintaining multi-language pre-commit hooks."

The key feature of pre-commit is that it creates an execution environment for itself in order to enable running hooks without messing with (or creating conflicts with) your development or operating environment.

pre-commit uses a configuration file (.pre-commit-config.yaml) to determine which hooks to run and how to handle them. These hooks can come from public or private repositories and there's a pretty solid mechanism for dealing with dependencies.

I'd discovered the pre-commit project when looking at another open-source project that used it to maintain a level of code consistency. To carry this out, pre-commit can be used to update files during the commit phase to bring those files into alignment with the standards (and verify correctness, run lint programs, etc.)

Pre-commit can be installed on macOS using homebrew with

# brew install pre-commit

Once installed, you can add a pre-commit configuration by creating a .pre-commit-config.yaml file and putting appropriate contents in it. Here's an example config that cleans up yaml, end of file, and trailing whitespace:

repos:
-   repo: https://github.com/pre-commit/pre-commit-hooks
    rev: v2.3.0
    hooks:
    -   id: check-yaml
    -   id: end-of-file-fixer
    -   id: trailing-whitespace

Install the git hook scripts with the install command:

# pre-commit install

And now give it a shot by running the command against all of your files:

# pre-commit run -a

It's not necessary to use pre-commit run, since the whole point of the pre-commit hooks is that they run before code is committed. However, if you make a change to your pre-commit configuration and want to bring the older content into line, you can use pre-commit run to clean up existing code to the new standards.

All told, it's pretty spiffy. I decided to use it to check my blog content, but that's a story for another post.