Serverless OpenAPI Generator

A simple OpenAPI 3 definition generator for Serverless projects that follows the OpenAPI specification structure.

Usage

Install

npm install serverless-openapi --save-dev

Configuration

Add this plugin to the plugins section of your serverless.yml file.

plugins:
  - serverless-openapi

Generating a defintion file

serverless openapi

Command Line Options

Name	Command	Shortcut	Type	Required?	Description	Default
Output File Location	--output	-o	string	Optional	The output file location	openapi.yml
OpenAPI Definition Format	--format	-f	json | yaml	Optional	The format of the OpenAPI definition file.	yaml

Separating definitions into their own file

OpenAPI defintions can get quite verbose. You can break these out into their own file, such as severerless.openapi.yml and then import them like such:

custom:
  openapi: ${file(serverless.openapi.yml):openapi}

Sample Definitions

This plugin parses your serverless.yml file and extracts info and components defintions from custom.openapi, paths and HTTP methods from functions.events.http, and path definitions functions.events.http.openapi. It maintains the OpenAPI specification structure.

Openapi Field

custom:
  openapi:
    openapi: '3.0.3' # The version of OpenAPI you want to validate against

Info Field

custom:
  openapi:
    title: Sample Pet Store App
    description: This is a sample server for a pet store.
    termsOfService: http://example.com/terms/
    contact:
      name: API Support
      url: http://www.example.com/support
      email: [e-mail]
    license:
      name: Apache 2.0
      url: https://www.apache.org/licenses/LICENSE-2.0.html
    version: 1.0.1

Servers Field

custom:
  openapi:
    servers:
      - url: https://development.gigantic-server.com/v1
        description: Development server
      - url: https://staging.gigantic-server.com/v1
        description: Staging server
      - url: https://api.gigantic-server.com/v1
        description: Production server

Components Field

Schemas Field with Serverless File Import

custom:
  openapi:
    components:
      schemas:
        ErrorResponse: ${file(schemas/Error.json)}

Schemas Field with Schema Reference

custom:
  openapi:
    components:
      schemas:
        ErrorResponse: 
          $ref: '#/components/schemas/ErrorResponse'

Security Schemes

custom:
  openapi:
    components:
      securitySchemes:
        PetAuth:
          type: oauth2
          flows: 
            implicit:
              authorizationUrl: https://example.com/api/oauth/dialog
              scopes:
                write:pets: modify pets in your account
                read:pets: read your pets
            authorizationCode:
              authorizationUrl: https://example.com/api/oauth/dialog
              tokenUrl: https://example.com/api/oauth/token
              scopes:
                write:pets: modify pets in your account
                read:pets: read your pets 

Security Field

custom:
  openapi:
    security:
      - PetAuth:
        - read:pets
        - write:pets

Paths Field (Function Definitions)

functions:
  RetrievePets:
    name: RetrievePets-Dev
    events:
      - http:
          method: get
          path: /pets
          openapi:
            summary: Retrieve pets
            description: Retrieves pets
            tags:
              - Pets
            security:
              - PetAuth:
                  - read:pets
            responses:
              '200':
                description: An API Query response with pets
                content:
                  application/json:
                    schema:
                      $ref: '#/components/schemas/RetrievePetsResponse'
              '400':
                description: An invalid request error
                content:
                  application/json:
                    schema:
                      $ref: '#/components/schemas/ErrorResponse'
              '401':
                description: An unauthorized error
                content:
                  application/json:
                    schema:
                      $ref: '#/components/schemas/ErrorResponse'
              '500':
                description: An unknown error
                content:
                  application/json:
                    schema:
                      $ref: '#/components/schemas/ErrorResponse'