GitHub Check Mergeability and Merge a Pull Request

arazzo: 1.0.1
info:
  title: GitHub Check Mergeability and Merge a Pull Request
  summary: Fetch a pull request, confirm it is mergeable, then merge it.
  description: >-
    A guarded merge pattern that avoids attempting to merge a pull request that
    GitHub has flagged as not mergeable. The workflow fetches the pull request,
    branches on its mergeable flag, and only proceeds to merge when the pull
    request reports as mergeable. Every step spells out its request inline so
    the flow can be read and executed without opening the underlying OpenAPI
    description.
  version: 1.0.0
sourceDescriptions:
- name: githubRepoPullsApi
  url: ../openapi/github-repo-pulls-api-openapi.yml
  type: openapi
workflows:
- workflowId: review-and-merge-pull-request
  summary: Get a pull request, branch on its mergeable flag, and merge when ready.
  description: >-
    Reads the pull request, and when the mergeable flag is true performs the
    merge using the configured merge method.
  inputs:
    type: object
    required:
    - githubToken
    - owner
    - repo
    - pullNumber
    properties:
      githubToken:
        type: string
        description: A GitHub token with repo scope, passed as a Bearer credential.
      owner:
        type: string
        description: The account owner of the repository.
      repo:
        type: string
        description: The name of the repository.
      pullNumber:
        type: integer
        description: The number that identifies the pull request.
      mergeMethod:
        type: string
        description: The merge method to use (merge, squash, or rebase).
  steps:
  - stepId: getPull
    description: >-
      Fetch the pull request to read its mergeable flag before attempting a
      merge.
    operationId: getPullRequest
    parameters:
    - name: Authorization
      in: header
      value: Bearer $inputs.githubToken
    - name: owner
      in: path
      value: $inputs.owner
    - name: repo
      in: path
      value: $inputs.repo
    - name: pull_number
      in: path
      value: $inputs.pullNumber
    successCriteria:
    - condition: $statusCode == 200
    outputs:
      mergeable: $response.body#/mergeable
      headSha: $response.body#/head/sha
    onSuccess:
    - name: isMergeable
      type: goto
      stepId: mergePull
      criteria:
      - context: $response.body
        condition: $.mergeable == true
        type: jsonpath
    - name: notMergeable
      type: end
      criteria:
      - context: $response.body
        condition: $.mergeable != true
        type: jsonpath
  - stepId: mergePull
    description: >-
      Merge the pull request using the supplied merge method now that it has
      been confirmed mergeable.
    operationId: mergePullRequest
    parameters:
    - name: Authorization
      in: header
      value: Bearer $inputs.githubToken
    - name: owner
      in: path
      value: $inputs.owner
    - name: repo
      in: path
      value: $inputs.repo
    - name: pull_number
      in: path
      value: $inputs.pullNumber
    requestBody:
      contentType: application/json
      payload:
        merge_method: $inputs.mergeMethod
        sha: $steps.getPull.outputs.headSha
    successCriteria:
    - condition: $statusCode == 200
    outputs:
      merged: $response.body#/merged
      mergeSha: $response.body#/sha
  outputs:
    merged: $steps.mergePull.outputs.merged
    mergeSha: $steps.mergePull.outputs.mergeSha