Simple OpenAPI 3 spec

api.yaml

openapi: "3.0.0"
info:
  title: Simple API overview
  version: 2.0.0
paths:
  /:
    get:
      summary: Show the version of the API
      responses:
        '200':
          $ref: '#/components/responses/VersionResponse'

      
components:
  responses:
    VersionResponse:
      description: Version response object
      headers:
        X-Request-Id:
          $ref: '#/components/headers/X-Request-Id'
      content:
        application/json:
          schema:
            $ref: "#/components/schemas/Version"

  headers:
    X-Request-Id:
      required: true
      description: unique ID for the request
      schema:
        $ref: '#/components/schemas/XRequestId'

  schemas:
    Version:
      type: object
      required:
        - version
      properties:
        version:
          type: string
          example: 1.23.45
          pattern: ^\d\.\d\.\d$
    
    XRequestId:
      description: unique ID for the request
      type: string
      format: uuid