Only run job on specific branch with GitHub Actions

Question

In a recent update you can now put if conditionals at job level. See the documentation here. https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions#jobsjob_idif

I tested this workflow which runs the job test on every push, but only runs deploy on the master branch.

name: my workflow
on: push
jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - name: Execute tests
        run: exit 0
  deploy:
    runs-on: ubuntu-latest
    needs: test
    if: github.ref == 'refs/heads/master'
    steps:
      - name: Deploy app
        run: exit 0

What follows is my original answer, and an alternative solution if you prefer to have separate workflows.

The first workflow runs for every branch except master. In this workflow you run tests only.

on:
  push:
    branches:
      - '*'
      - '!master'

The second workflow runs for just master and runs both your tests and deploys if the tests were successfully passed.

on:
  push:
    branches:
      - master

Here is what I've done for steps that should only run on a specific branch.

- name: Publish Image
  # Develop branch only
  if: github.ref == 'refs/heads/develop'
  run: |
    ... publish commands ...

Most answers provide a solution for one single branch. To restrict the job to run on any specific set of branches, you can do it using the if conditional with multiple disjunction (||) operators; but this is too verbose and doesn't respect the DRY principle.

The same can be archived with less repetition using the contains function.

Using contains:

contains('
  refs/heads/dev
  refs/heads/staging
  refs/heads/production
', github.ref)

compared to using multiple ||:

github.ref == 'refs/heads/dev' || github.ref == 'refs/heads/staging' || github.ref == 'refs/heads/production' || …

Full example:

---
on: push
jobs:
  test:
    name: Test
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v2
    - name: Run tests
      run: …

  deployment:
    name: Deployment
    runs-on: ubuntu-latest
    needs: [test]
    if:
      contains('
        refs/heads/dev
        refs/heads/staging
        refs/heads/production
      ', github.ref)
    steps:
    - uses: actions/checkout@v2
    - name: Deploy
      run: …

2021 update

I know it's possible to only run entire workflows on a specific branch, however that would mean I would have a "test" workflow and a "deploy" workflow.

This sounds like a solution, however they would run parallel. In an ideal world, the tests would run first, and only if they succeed, then the deploy job would start. This isn't the case when using 2 separate workflows.

You can now use the event workflow_run to achieve the part the tests would run first, and only if they succeed, then the deploy job would start (read on to see how):

Documentation page of workflow_run

https://docs.github.com/en/actions/learn-github-actions/events-that-trigger-workflows#workflow_run

This event occurs when a workflow run is requested or completed, and allows you to execute a workflow based on the finished result of another workflow. A workflow run is triggered regardless of the result of the previous workflow.

For example, if your pull_request workflow generates build artifacts, you can create a new workflow that uses workflow_run to analyze the results and add a comment to the original pull request.

Now, considering OP's initial issue:

I want the tests to run on every branch, but deploying should only happen when something gets pushed to master

This now could be solved like this:

The following setup is working, a few minutes ago I just implemented the same logic in one of my repository

Workflow <your_repo>/.github/workflows/tests.yml

name: My tests workflow

on:
  push:
    branches:
      - master
  pull_request: {}

jobs:
  test:

    # ... your implementation to run your tests

Workflow <your_repo>/.github/workflows/deploy.yml

name: My deploy workflow

on:
  workflow_run:
    workflows: My tests workflow # Reuse the name of your tests workflow
    branches: master
    types: completed

jobs:
  deploy:
    # `if` required because a workflow run is triggered regardless of
    # the result of the previous workflow (see the documentation page)
    if: ${{ github.event.workflow_run.conclusion == 'success' }}

    # ... your implementation to deploy your project

While you can't have conditions at job level at this moment, you can have conditions at step level - see Contexts and expression syntax for GitHub Actions.

For getting a branch name, current solution is to check GITHUB_REF environment variable - see Default environment variables and this question for details.

Putting it all together - if you decide to go with accepted answer in last link, your workflow might look like this:

jobs:

 test:
  runs-on: ubuntu-latest
  steps:
  - name: Run tests
    run: ./my-tests.sh

 deploy:
  runs-on: ubuntu-latest
  needs: test
  steps:
  - name: Extract branch name
    shell: bash
    run: echo "##[set-output name=branch;]$(echo ${GITHUB_REF##*/})"
    id: extract_branch
  - name: Deploy
    run: ./deploy.sh
    if: steps.extract_branch.outputs.branch == 'master'

If you'd rather keep everything in workflow file instead of separated script, you can always add if to each step in given job.

---

I hope it's just a temporary solution/workaround, and job conditions are going to be added before end of beta.

The following worked for me inside a job:

Where a PR target branch is one of the following:

if: contains(github.base_ref, 'staging')
  || contains(github.base_ref, 'production')

When the source branch of the pull request is one of them below:

if: contains(github.head_ref, 'feature')
  || contains(github.head_ref, 'release')