When building deploy pipelines, referencing the name of the branch that a GitHub Actions workflow is running with can be useful.
I recently gave a talk on how platforms like Netlify build and deploy web applications using changes to GitHub branches. Part of the talk was a brief demonstration of how I built branch-based deployments into my SaaS.
The name of the current branch was passed into my deploy process using AWS SAM as a parameter to create resources in AWS unique to the name of the branch.
It’s rather straightforward with a simple bash step.
How to use the branch name in a job
Start by adding a step into the workflow that extracts the name of the branch from the workflow context and sets it on a job parameter:
shell: bash
# 👉 We’re extracting the name of the branch and setting it to the
# ‘branch’ variable in this step
run: echo “branch=${GITHUB_HEAD_REF:-${GITHUB_REF#refs/heads/}}” >> $GITHUB_OUTPUT
# 👉 The ID of the branch
id: extract_branch
You can now reference the value throughout the remainder of the job like so:
shell: bash
working-directory: backend/stack
env:
GOOS: linux
GOARCH: amd64
CGO_ENABLED: 0
# 👉 Notice how the ID of the previous step is referenced.
SITE_ALIAS: ${{ steps.extract_branch.outputs.branch }}
run: make deploy-branch
Here is the YAML for the entire workflow used in this example:
on:
workflow_dispatch:
push:
branches:
– qa
paths:
– backend/**
env:
AWS_ACCESS_KEY_ID: ${{ secrets.AWS_ACCESS_KEY_ID }}
AWS_SECRET_ACCESS_KEY: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
AWS_DEFAULT_REGION: ‘us-west-1′
jobs:
deploy-backend:
environment: ${{ github.ref_name == ‘main’ && ‘production’ || github.ref_name }}
name: Deploy backend
runs-on: ubuntu-latest
steps:
– name: Extract branch name
shell: bash
run: echo “branch=${GITHUB_HEAD_REF:-${GITHUB_REF#refs/heads/}}” >> $GITHUB_OUTPUT
id: extract_branch
– name: Checkout
uses: actions/checkout@v3
– uses: aws-actions/setup-sam@v2
with:
use-installer: true
– name: Sam version
run: |
sam –version
– name: Write default params.json file
shell: bash
working-directory: backend/stack
run: |
echo “${{ secrets.PARAMS_JSON_ENCODED }}” >> params.encoded
base64 -d -i params.encoded >> params.json
cat params.json
– name: Transform configs
shell: bash
working-directory: scripts/transform-json
env:
SITE_ALIAS: ${{ steps.extract_branch.outputs.branch }}
BUNGIE_API_KEY: ${{ secrets.BUNGIE_API_KEY }}
CERT_ARN: ${{ secrets.CERT_ARN }}
DISCORD_FEEDBACK_WEBHOOK: ${{ secrets.DISCORD_FEEDBACK_WEBHOOK }}
OAUTH_CLIENT_ID: ${{ secrets.OAUTH_CLIENT_ID }}
OAUTH_CLIENT_SECRET: ${{ secrets.OAUTH_CLIENT_SECRET }}
STRIPE_ERROR_CB: ${{ secrets.STRIPE_ERROR_CB }}
STRIPE_KEY: ${{ secrets.STRIPE_KEY }}
STRIPE_SUCCESS_CB: ${{ secrets.STRIPE_SUCCESS_CB }}
STRIPE_WEBHOOK_KEY: ${{ secrets.STRIPE_WEBHOOK_KEY }}
run: |
go run main.go
–mapfile ../../backend/stack/transform_map.json
–configfile ../../backend/stack/params.json
cat ../../backend/stack/params.json
– name: Build & deploy
shell: bash
working-directory: backend/stack
env:
GOOS: linux
GOARCH: amd64
CGO_ENABLED: 0
SITE_ALIAS: ${{ steps.extract_branch.outputs.branch }}
run: make deploy-branch
All of this code is open source as well if you’d rather read it directly on GitHub: https://github.com/GuardianForge/guardianforge.net/blob/main/.github/workflows/deploy-backend-qa.yaml
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