How to get branch name on GitHub action?

Question

During a GitHub action, I'd like to know the name of the branch:

• for a push action: name of the current branch
• for a pull_request action: name of the target branch

I need a string like develop, master or feature/xxx (and not refs/pull/…).

The ${{ github.ref }} var gives me refs/heads/develop. How can I get only the develop?

Answer 1

Update: GitHub added the context variable ${{ github.ref_name }}, returning "The branch or tag name that triggered the workflow run."

Original Answer:

You can create a step output of the last part of GITHUB_REF like the following.

on: push
jobs:
  example:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2

      - name: Set output
        id: vars
        run: echo ::set-output name=short_ref::${GITHUB_REF#refs/*/}

      - name: Check output
        run: echo ${{ steps.vars.outputs.short_ref }}

Answer 2

This creates an environment variable GIT_BRANCH which has the following behavior:

• Outside of a PR, this is set to the branch short name (master, not refs/heads/master)
• Inside a PR, this is set to the target branch short name (master, not refs/pull/123/merge)

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout repository
        uses: actions/checkout@v2

      - name: Set environment variables
        run: |
          # Short name for current branch. For PRs, use target branch (base ref)
          GIT_BRANCH=${GITHUB_BASE_REF:-${GITHUB_REF#refs/heads/}}
          echo "GIT_BRANCH=$GIT_BRANCH" >> $GITHUB_ENV

How this works:

• GITHUB_BASE_REF is the short branch name for the target branch during a PR trigger, and it is empty otherwise.
• GITHUB_REF always has a value, but the value changes based on the context. Outside of a PR, GITHUB_REF is the "full" branch name (refs/heads/master). Inside of a PR, it is the PR branch name (refs/pull/123/merge).

So this script uses GITHUB_BASE_REF if set, otherwise it uses GITHUB_REF and removes the "refs/heads/" prefix.