If you’re looking for a deep dive on GitHub Actions, check out The Changelog #331: GitHub Actions is the next big thing with Kyle Daigle. Patrick Reynolds, writing on the GitHub Engineering blog:
Since the beta release of GitHub Actions last October, thousands of users have added workflow files to their repositories. But until now, those files only work with the tools GitHub provided: the Actions editor, the Actions execution platform, and the syntax highlighting built into pull requests. To expand that universe, we need to release the parser and the specification for the Actions workflow language as open source. Today, we’re doing that.
I also want to point out this “we believe” section of the post to key in on their intentions and willingness to provide the community with the necessary tools to make GitHub Actions all that it can be for the community.
We believe that tools beyond GitHub should be able to run workflows. We believe there should be programs to check, format, compose, and visualize workflow files. We believe that text editors can provide syntax highlighting and autocompletion for Actions workflows. And we believe all that can only happen if the Actions community is empowered to build these tools along with us. That can happen better and faster if there is a single language specification and a free parser implementation.