Use the buildspec.yml from another (Secondary Source) repo for your Source repo in AWS CodeBuild (Demonstrated with Cloudformation)

codebuild-secondary-buildspec.yml

  CodeBuildProject:
    Type: AWS::CodeBuild::Project
    Properties:
      Name: !Ref GitHubRepoName
      BadgeEnabled: true
      Description: Builds a Docker image using a BuildSpec from another repo
      ServiceRole: !ImportValue Your-CodeBuild-Role
      TimeoutInMinutes: 15
      Artifacts:
        Type: NO_ARTIFACTS
      Source:
        SourceIdentifier: my-repo
        Type: GitHub
        Location: !Sub https://github.com/${GitHubRepoOwner}/${GitHubRepoName}.git
        ReportBuildStatus: true
        GitCloneDepth: 1
        BuildSpec: ../the-name-of-the-buildspec-repo/buildspec.yml
      SecondarySources:
        - SourceIdentifier: the-buildspec-repo
          Type: GitHub
          Location: !Sub https://github.com/rupertbg/the-name-of-the-buildspec-repo.git
          ReportBuildStatus: false
          GitCloneDepth: 1
      Environment:
        Type: LINUX_CONTAINER
        ComputeType: BUILD_GENERAL1_SMALL
        Image: aws/codebuild/standard:3.0
        PrivilegedMode: true
        EnvironmentVariables:
          - Name: CONTAINER_NAME
            Value: !Ref ContainerName
          - Name: ECR_REPO
            Value: !Ref ECRRegistry

Hi! I'm trying to use your code, but I looking the following error in the aws cli console
An error occurred (ValidationError) when calling the CreateStack operation: Template format error: At least one Resources member must be defined.

Hi! I'm trying to use your code, but I looking the following error in the aws cli console An error occurred (ValidationError) when calling the CreateStack operation: Template format error: At least one Resources member must be defined.

Hey bud, this is just a snippet of a template, a single resource you would add to a complete Cloudformation template.