We're looking at a different kind of action today! This action doesn't actually do anything. Instead, it makes more information available in your workflow and the environment for other actions to use.
Fact Sheet | |
---|---|
Author | rlespinasse |
Contributors | 9 |
Stars | 106 |
Repo | https://github.com/rlespinasse/github-slug-action |
Marketplace | https://github.com/marketplace/actions/github-slug-action |
What does it do?
The github-slug-ref
action provides information that’s commonly needed in workflows in a useful format. By default, variables such as GITHUB_REF
are in the format refs/heads/main
or refs/tags/v1.0.0
. This catches people out as they’re not used to thinking about if what they’re referencing is a branch or a tag, and they’re definitely not used to the refs
prefix.
Once the rlespinasse/github-slug-action
action has been included in your workflow, some new environment variables will be available. To include it, add a uses
entry within your steps
key:
name: Slug Demo
on: push
jobs:
demo:
runs-on: ubuntu-latest
steps:
- uses: rlespinasse/github-slug-action@v3.x
If we think about GITHUB_REF
from above, GITHUB_REF_SLUG
is available after including this action. If GITHUB_REF
was refs/heads/main
, GITHUB_REF_SLUG
will be main
. If the input was refs/tags/v1.0.0
, GITHUB_REF_SLUG
will be v1.0.0
. If you’d like to see a full list of transformations, see the slug variables docs. If you’re looking for slugs that are safe to use in a URL, you might be interested in the URL slug variables too.
Another feature of the action is short variables. In addition to the full sha
(available in GITHUB_SHA
), this action will make an 8 character prefix available in GITHUB_SHA_SHORT
. This can be useful is you need a semi-unique identifier and want a shorter key than the full sha
.
In addition to manipulating the existing environment variables, the action also makes some of the information from github.event
available as an environment variable. For example, github.event.pull_request.head.sha
is available as GITHUB_EVENT_PULL_REQUEST_HEAD_SHA_SHORT
. This is useful when you’re writing bash scripts and can’t parse event.json
.
How does it work?
Looking at the source code, this action is a large collection of regular expressions. It handles cases such as:
- Replacing any non-alphanumeric character
- Removing refs/* from GITHUB_REF
- Ensure that all slugs are less than 63 characters long
If you want to see all of the variables it’s creating in the source code, they’re all available in main.ts
.
The action itself is compiled and pushed to the repo so that people can use it directly. This isn't a pattern I like personally (I prefer to use the build and tag action) but it means that consumers can use the javascript runtime so it's a reasonable trade off.
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