Getting current branch and commit hash in GitHub action

Question

I want to build a docker image using a GitHub action, migrating from TeamCity.

In the build script, I want to tag the image with a combination of branch and commit, e.g.

Answer 1

from Using environment variables

github provides two variables that are useful here, you'll need to process them a bit to get the values you desire:

GITHUB_SHA: The commit SHA that triggered the workflow. For example, ffac537e6cbbf934b08745a378932722df287a53.

GITHUB_REF: The branch or tag ref that triggered the workflow. For example, refs/heads/feature-branch-1. If neither a branch or tag is available for the event type, the variable will not exist.

The short values can be extracted like this:

git_hash=$(git rev-parse --short "$GITHUB_SHA")
git_branch=${GITHUB_REF#refs/heads/}

Answer 2

Using https://github.com/tj-actions/branch-names provides an output which also works for push and pull_request events

...
    steps:
      - uses: actions/checkout@v2
      - name: Get branch names
        uses: tj-actions/branch-names@v2.1
        id: branch-names
      
      - name: Current branch name
        if: github.event_name == 'pull_request'
        run: |
          echo "${{ steps.branch-name.outputs.current_branch }}"
        # Outputs: "feature/test" current PR branch.
      
      - name: Current branch name
        if: github.event_name == 'push'
        run: |
          echo "${{ steps.branch-name.outputs.current_branch }}"
        # Outputs: "main" the default branch that triggered the push event.
      
      - name: Get Ref brach name
        run: |
          echo "${{ steps.branch-name.outputs.ref_branch }}"
        #  Outputs: "main" for non PR branches | "1/merge" for a PR branch

      - name: Get Head Ref branch name
        if: github.event_name == 'pull_request'
        run: |
          echo "${{ steps.branch-name.outputs.head_ref_branch }}"
        # Outputs: "feature/test" current PR branch.

      - name: Get Base Ref branch name
        if: github.event_name == 'pull_request'
        run: |
          echo "${{ steps.branch-name.outputs.base_ref_branch }}"
        # Outputs: "main" for main <- PR branch.

Answer 3

You can get it this way in your sh file -

BRANCH_NAME=$(echo $GITHUB_REF | cut -d'/' -f 3)
GITHUB_SHA_SHORT=$(echo $GITHUB_SHA | cut -c1-8)

Answer 4

A handy way to get the currrent branch and commit sha on the workflow could be getting it and saving on a "variable".

  - name: Declare some variables
    id: vars
    shell: bash
    run: |
      echo "##[set-output name=branch;]$(echo ${GITHUB_REF#refs/heads/})"
      echo "::set-output name=sha_short::$(git rev-parse --short HEAD)"

  - name: Another step
    run: |
      echo "Branch: ${{ steps.vars.outputs.branch }}"
      echo "Sha: ${{ steps.vars.outputs.sha_short }}"

Maybe your docker-build.sh could receive the branch and she as parameter, os the full version as parameter.

  - name: Create docker image
     run: ./docker-build.sh "${{ steps.vars.outputs.branch }}.${{ steps.vars.outputs.sha_short }}"

OR JUST

  - name: Create docker image
     run: ./docker-build.sh "${GITHUB_REF#refs/heads/}.${GITHUB_SHA}"

---

On this action you can see many tests I done to see what works, what don't.

Answer 5

Another approach is to use github context.

- name: Create docker image
  run: ./docker-build.sh ${{ github.head_ref }}.${{ github.sha }}

The benefit of this approach is that you don't have to add a step to set the values. Note that it uses the full version of the sha (not the short version).