GitHub Actions GIT_BRANCH environment variable

Question

I have a GitHub action running my unit tests for a web app. I run CodeClimate test reporting from this action.

CodeClimate requires two environment variables to be set for the report to be correctly sent. These are;

• GIT_SHA
• GIT_BRANCH

GitHub actions makes the git commit sha avaiable through the github context via github.sha so I can set an environment variable on the action like this;

env:
 GIT_SHA: ${{ github.sha }}

However github actions does not make the branch name available.

It does provide a default environment variable called GITHUB_REF this is the full ref but I understand that I can grab the short ref i.e. the branch name using this shorthand syntax $GITHUB_REF##*/

The problem I have is that I cannot set an env variable called GITHUB_BRANCH with this value $GITHUB_REF##*/

Does anyone how I might get the branch name and set it to the environment variable GIT_BRANCH so the CodeClimate test script would be able to use it.

Ultimately I want my env config to look like this:

env:
 GIT_SHA: <git commit sha>
 GIT_BRANCH: <current git branch>

• anthony sottile: Does this answer your question? Getting current branch and commit hash in GitHub action
• anthony sottile: (so tl;dr, you don't need to do any special environment setup in github actions, the variables are already there)
• MajorAtmosphere: The variables are there correct, however not under the name that CodeClimate requires. Add it seems you cant set an environment based on the value of another.
• anthony sottile: ${{ env.GITHUB_BRANCH }} for example should work
• MajorAtmosphere: It looks like setting GIT_BRANCH: ${{ github.head_ref }} may work. Although not sure this will work for a push to the main branch as that would be on the push event and not the pull_request event

Answer 1

Ultimately I want my env config to look like this:

env:
 GIT_SHA: <git commit sha>
 GIT_BRANCH: <current git branch>

You can achieve the same effect (setting the environment variables) not only in the workflow definition but by setting the variables dynamically in a dedicated workflow step. You can do it by environment files and built-in GITHUB_SHA and GITHUB_BRANCH variables:

jobs:
 set-env:
 runs-on: ubuntu-latest
 steps:
 - name: Set environment variables
 run: |
 echo "GIT_SHA=${GITHUB_SHA}" >> $GITHUB_ENV
 echo "GIT_BRANCH=${GITHUB_REF##*/}" >> $GITHUB_ENV
 - name: Use environment variables
 run: |
 echo "GIT_SHA=${GIT_SHA}"
 echo "GIT_BRANCH=${GIT_BRANCH}"

Executing the workflow should give you the output:

enter image description here

• Dan Ciborowski - MSFT: this is extremely helpful but very buried in the answer ${GITHUB_REF##*/}

Answer 2

Indeed, rather than using GITHUB_REF, it could be useful to use GITHUB_HEAD_REF or GITHUB_BASE_REF to figure out the real branch names (above all, if workflow is associated to a PR):

Examples of output:

 GITHUB_REF="refs/pull/4/merge"
 GITHUB_BASE_REF="main"
 GITHUB_HEAD_REF="key_advertisement"

More information here: https://docs.github.com/en/actions/learn-github-actions/contexts#github-context