get GitHub git branch for AWS CodeBuild

Question

I\'m setup AWS CodeBuild to build automatically from GitHub. Other CI services provide an environment variable for the branch, but I can\'t find one for AWS CodeBuild. There is

Answer 1

CodeBuild strips git information from the filesystem. There is no .git folder, so running a git command will be fruitless.

I have added a parameter to my CI/CD CloudFormation template:

  GitBranch:
    Description: Github branch to be deployed
    Type: String
    Default: master

And I have a Bash script that creates / updates the CI/CD stack:

readonly git_branch=$(git branch 2>/dev/null | grep "^*" | colrm 1 2)

aws cloudformation create-stack \
  --stack-name ${cicd_stack_name} \
  --parameters ParameterKey=GitBranch,ParameterValue=${git_branch}

I then export the value as an environment variable to CodeBuild machine:

CodeBuildProject:
Type: AWS::CodeBuild::Project
Properties:
  Environment:
    Type: LINUX_CONTAINER
    Image: aws/codebuild/java:openjdk-8
    EnvironmentVariables:
      - Name: GIT_BRANCH
        Value: !Ref GitBranch

Now I have access to it in my buildspec.yml:

post_build:
  commands:
    - echo [PHASE] Entered the post_build phase...
    - echo "[DEBUG] Git branch ${GIT_BRANCH}"