orb.yaml

version: 2.1
description: |
  Multirepo and monorepo support for CircleCI.

  Source: https://github.com/dnephin/multirepo-orb

  Use the `multiorb/run-job-for-paths` command in each job that should be
  run when the paths change. Only the job itself will be halted, so all
  subsequent jobs in the workflow must call the same command.

commands:
  run-job-for-paths:
    description: |
      Continue running the job if any file in paths has been modified since
      the last commit shared with the upstream git branch (default: origin/master).

      This command must be run after `checkout`.
  
      This command allows you to skip all of the subsequent steps in a job so that any
      repository with multiple workflows, or multiple flows within a single
      workflow, will only run CI jobs relevant to the files that changed.
  
      If you have a multipurpose git repository with independent directory trees
      this command allows you to run the tests for only the services which have been
      modified relative to the upstream branch.
  
    parameters:
      paths:
        type: string
        description: |
          A list of file paths used with 'git diff' to check for modification.
      upstream_branch:
        type: string
        description: |
          The upstream branch used with 'git merge-base' to find the most recent
          commit shared by HEAD and the upstream branch.
        default: origin/master
      working_directory:
        type: string
        description: |
          Directory to change to before executing the command.
        default: "$PWD"
      run_on_upstream:
        type: boolean
        description: |
          When run_on_upstream is true, and HEAD matches the upstream_branch the
          job always run. When false the job will not run when HEAD matches
          the upstream_branch.
        default: true
    steps:
      - run:
          name: Check if job should run
          command: |
            cd << parameters.working_directory >>

            upstream="$(git merge-base HEAD << parameters.upstream_branch >>)"
            echo "Comparing to upstream commit $upstream"

            <<# parameters.run_on_upstream >>
            if [[ "$(git rev-parse HEAD)" == "$upstream" ]]; then
              echo "HEAD matches upstream, running with no diff"
              exit 0
            fi
            <</ parameters.run_on_upstream >>

            if [[ -z "$upstream" ]]; then
              echo "git merge-base failed"
              exit 1
            fi
  
            # Print the diff
            PAGER=cat git diff --stat=80 $upstream -- << parameters.paths >>
  
            # Halt if no diff
            if git diff --quiet $upstream -- << parameters.paths >>; then
              echo "Skipping job, no files modified"
              circleci-agent step halt
            fi