Awesome

GitHub Slug action

This GitHub Action will expose the slug/short values of some GitHub environment variables inside your GitHub workflow.

Overview

SLUG on a variable will

• put the variable content in lower case
• replace any character by - except 0-9, a-z, ., and _
• remove leading - characters
• limit the string size to 63 characters
• remove trailing - characters

Others Slug-ish variables are available

• SLUG_URL on a variable to have a slug variable compliant to be used in a URL
  • Like SLUG but ., and _ are also replaced by -
• SHORT on a variable will limit the string size to ~8 characters
  • Useful for sha value
• <KEY>_PART on a variable will give a part of a variable defined by a key
  • Like GITHUB_REPOSITORY_OWNER_PART for the owner part of GITHUB_REPOSITORY
• <VAR>_CS on others variables to keep the value case-sensitive
  • Like GITHUB_REF_SLUG_CS

Installation

Add this step to your workflow

steps:
  - name: Inject enhanced GitHub environment variables
    uses: rlespinasse/github-slug-action@v5

[!CAUTION] Use Dependabot to maintain your github-slug-action version updated in your GitHub workflows.

Configuration Options

[!TIP] Check for more examples (OS usage, URL use, ...)

With a prefix

steps:
  - name: Inject enhanced GitHub environment variables
    uses: rlespinasse/github-slug-action@v5
    with:
      prefix: CI_

With another max length for slug values

steps:
  - name: Inject enhanced GitHub environment variables
    uses: rlespinasse/github-slug-action@v5
    with:
      slug-maxlength: 80 # Use 'nolimit' to remove use of a max length (Default to 63)

With another length for short values

steps:
  - name: Inject enhanced GitHub environment variables
    uses: rlespinasse/github-slug-action@v5
    with:
      short-length: 7 # By default it's up to Git to decide, use 8 to have the v3.x behaviour

The length of a short sha depends of the size of your repository and can differ over time :

• set 7 to keep the small repository behaviour,
• set 8 to reproduce v3 behaviour,
• set 4 as the minimum length possible.

[!WARNING] If you leave it empty, you need to checkout the source first in order to let Git decide the size by itself by using git rev-parse behaviour.

The default is the effective value of the core.abbrev configuration variable.

Available Environment variables

[!TIP] If you don't find what you search for

• Read more about available GitHub variables, and propose a new custom variable.
• Use your own variable with slugify-value, or shortify-git-revision for git reference.

Enhanced variables

• GITHUB_REF_POINT will contains the reference name (branch or tag)
  • based on GITHUB_HEAD_REF in a pull-request* event context,
  • based on GITHUB_REF_NAME in others event context.

[!NOTE] All enhanced variables are available in all slug formats.

Partial variables

Slug variables

[!TIP] Available in standard and case-sensitive (_CS) versions.

URL-Safe Slug variables

Same as slug variables but URL-compliant

[!TIP] Available in standard and case-sensitive (_CS) versions.

Short variables

Migration from previous versions

v4 to v5

The GITHUB_REF_NAME SLUG/SLUG_URL variables doesn't work the same way as before

[!TIP] If you use v5 or related versions, you need to use GITHUB_REF_POINT instead of GITHUB_REF_NAME to get the behaviour of the v4 action.

Before v5, the behaviour was the same as the GitHub one except on pull_request* workflows (Ready the full story).

• ${{ env.GITHUB_REF_NAME }} will serve the behaviour of this action,
• $GITHUB_REF_NAME will serve the behaviour of GitHub Action.

On pull_request* workflows, the content will be <PR-number>/merge instead of the branch name. So you need to use GITHUB_REF_POINT instead

steps:
  - name: Inject enhanced GitHub environment variables
    uses: rlespinasse/github-slug-action@v5
  - run: |
      echo "Branch Name: ${GITHUB_REF_POINT}"
    shell: bash

Then ${{ env.GITHUB_REF_POINT }}, and $GITHUB_REF_POINT will serve the behaviour of this action. And ${{ env.GITHUB_REF_NAME }}, and $GITHUB_REF_NAME will serve the behaviour of GitHub Action.

v3 to v4

Since v4, it's Git who manage the short variables by using git rev-parse behaviour. The length of a short sha depends of the size of your repository and can differ over time.

To manage that moving length, you can use short-length input

• set 7 to reproduce small repository behaviour
• set 8 to reproduce v3 behaviour

[!WARNING] The minimum length is 4, the default is the effective value of the core.abbrev configuration variable.

So to reproduce previous behaviour, use

steps:
  - name: Inject enhanced GitHub environment variables
    uses: rlespinasse/github-slug-action@v5
    with:
      short-length: 8 # Same as v3 and before

Troubleshooting

One of the environment variables doesn't work as intended

[!WARNING] When you set a custom environment variable, you cannot use any of the default environment variable names. For a complete list of these, see Default environment variables. If you attempt to override the value of one of these default environment variables, the assignment is ignored.

If a variable start to be used as default environment variable, the environment variable may have a different behaviour than the expected one.

If this append, the ${{ env.GITHUB_AWESOME_VARIABLE }} and $GITHUB_AWESOME_VARIABLE expression will not works in the same way.

• ${{ env.GITHUB_AWESOME_VARIABLE }} will serve the behaviour of this action,
• $GITHUB_AWESOME_VARIABLE will serve the behaviour of GitHub Action.

Otherwise the two expression will serve the behaviour of this action. This will not occurs if you use the prefix input to avoid the issue.

[!IMPORTANT] If detected, the maintainers of this action will choose the best course of action depending of the impact.

An action could not be found at the URI

If your workflow fail on the Set up job task with this kind of log

Download action repository 'rlespinasse/github-slug-action@GIT_REFERENCE'
##[error]An action could not be found at the URI 'https://api.github.com/repos/rlespinasse/github-slug-action/tarball/GIT_REFERENCE'

If the GIT_REFERENCE value is

• v4.x or after, the branch don't exists anymore following the end-of-life for a branch security process.
• master, the branch don't exists anymore, read more about it on the corresponding issue (EOL issue)

Please, use the current major tag v5 or a version tag (see releases pages) in order to fix your workflow.

Thanks for talking about us

In English :gb:

• Action spotlight by Michael Heap
• Serverless Deploy Previews on GitHub Actions
• Let's Build a Continuous Delivery and Branching Process with GitHub Actions, Vercel and Heroku

In French :fr:

• Mettre en place une CI/CD Angular avec GitHub Actions & Netlify
• GitHub Actions : enfin des pipelines accessibles aux développeurs GitHub-slug-action : 5 ans d'open source pour cette GitHub Action essentielle au CI/CD

In Chinese :cn:

• 利用github-slug-action暴漏GitHub Action上下文中的关键变量

The next one is you. Don't hesitate to add youself to one of these lists.