Serverless OpenAPI Documentation Plugin

Generates OpenAPI 3.0.0 documentation from serverless configuration files. OpenAPI is formerly known as Swagger. The configuration is inspired by the format used in serverless-aws-documentation.

Works well with ReDoc.

• Usage
  • Options
  • Configuration
    • Models
    • Functions
    • queryParams
    • pathParams
    • cookieParams
    • requestModels
    • methodResponses
• Example configuration
• Install

Usage

This plugin requires additional configuration to use, see the "Configuration" section for how to configure the plugin to generate documentation.

Below are the commandline options to run the generator:

serverless openapi generate [options]

Options

Plugin: ServerlessOpenAPIDocumentation
openapi generate  ...................... Generate OpenAPI v3 Documentation
    --output / -o ...................... Output file location [default: openapi.yml|json]
    --format / -f ...................... OpenAPI file format (yml|json) [default: yml]
    --indent / -i ...................... File indentation in spaces [default: 2]
    --help / -h   ...................... Help

Configuration

To configure this plugin to generate valid OpenAPI documentation there are two places you'll need to modify in your serverless.yml file, the custom variables section and the http event section for each given function in your service.

This plugin is compatible with the same documentation configuration structure in serverless-aws-documentation and can run beside it.

The custom section of your serverless.yml can be configured as below:

custom:
  documentation:
    version: '1'
    title: 'My API'
    description: 'This is my API'
    # https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.2.md#securitySchemeObject
    securitySchemes: {}
    # https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.2.md#security-requirement-object
    security: {}
    models: {}

These configurations can be quite verbose; you can separate it out into it's own file, such as serverless.doc.yml as below:

custom:
  serverless-offline: # local testing plugin
    httpPort: 8000
    lambdaPort: 8002
    noPrependStageInUrl: true # important for local docs routing working correctly
  documentation: ${file(serverless.doc.yml):documentation}

functions:
  myFunc:
    events:
      - http:
          path: getStuff
          method: get
          documentation: ${file(serverless.doc.yml):endpoints.myFunc}

For more info on serverless.yml syntax, see their docs.

Models

Models contain additional information that you can use to define schemas for endpoints. You must define the content type for each schema that you provide in the models.

The required directives for the models section are as follow:

• name: the name of the schema
• description: a description of the schema
• contentType: the content type of the described request/response (ie. application/json or application/xml).
• schema: The JSON Schema (website) that describes the model. You can either:
  • use inline YAML to define these
  • use serverless' functionality to merge in external schema file
  • specify a path to json schema in which case if you reuse some types in multiple schemas - they will be included in resulting components once instead of duplicated for each referencing schema

custom:
  documentation:
    models:
      - name: "PutDocumentRequest"
        description: "Inline schema example"
        contentType: "application/json"
        schema:
          $schema: "http://json-schema.org/draft-04/schema#"
          properties:
            SomeObject:
              type: "object"
              properties:
                SomeAttribute:
                  type: "string"
      - name: "PutDocumentResponse"
        description: "External file merge example"
        contentType: "application/json"
        schema: ${file(models/PutDocumentResponse.json)}
      - name: "ErrorResponse"
        description: "Path to a schema example"
        contentType: "application/json"
        schema: models/ErrorResponse.json

Functions

To define the documentation for a given function event, you need to create a documentation attribute for your http event in your serverless.yml file.

The documentation section of the event configuration can contain the following attributes:

• summary: a short description of the method
• description: a detailed description of the method
• tags: an array of tags for this event
• deprecated: boolean indicator that indicates clients should migrate away from this function
• requestBody: contains description of the request
  • description: a description of the request body
• requestModels: a list of models to describe the request bodies (see requestModels below)
• queryParams: a list of query parameters (see queryParams below)
• pathParams: a list of path parameters (see pathParams below)
• cookieParams: a list of cookie parameters (see cookieParams below)
• methodResponses: an array of response models and applicable status codes
  • statusCode: applicable http status code (ie. 200/404/500 etc.)
  • responseBody: contains description of the response
    • description: a description of the body response
  • responseHeaders: a list of response headers (see responseHeaders below)
  • responseModels: a list of models to describe the request bodies (see responseModels below) for each Content-Type

functions:
  createUser:
    handler: "handler.create"
    events:
      - http:
        path: "create"
        method: "post"
        documentation:
          summary: "Create User"
          description: "Creates a user and then sends a generated password email"
          requestBody:
            description: "A user information object"
          requestModels:
            application/json: "PutDocumentRequest"
          pathParams:
            - name: "username"
              description: "The username for a user to create"
              schema:
                type: "string"
                pattern: "^[-a-z0-9_]+$"
          queryParams:
            - name: "membershipType"
              description: "The user's Membership Type"
              schema:
                type: "string"
                enum:
                  - "premium"
                  - "standard"
          cookieParams:
            - name: "SessionId"
              description: "A Session ID variable"
              schema:
                type: "string"
          methodResponses:
            - statusCode: 201
              responseBody:
                description: "A user object along with generated API Keys"
              responseModels:
                application/json: "PutDocumentResponse"
            - statusCode: 500
              responseBody:
                description: "An error message when creating a new user"
              responseModels:
                application/json: "ErrorResponse"

queryParams

Query parameters can be described as follow:

• name: the name of the query variable
• description: a description of the query variable
• required: whether the query parameter is mandatory (boolean)
• schema: JSON schema (inline or file)

queryParams:
  - name: "filter"
    description: "The filter parameter"
    required: true
    schema:
      type: "string"

pathParams

They get derived form the event path thus do not need to be passed explicitly. Path parameters can be described as follows:

• name: the name of the query variable
• description: a description of the query variable
• schema: JSON schema (inline or file)

pathParams:
  - name: "usernameId"
    description: "The usernameId parameter"
    schema:
      type: "string"

cookieParams

Cookie parameters can be described as follows:

• name: the name of the query variable
• description: a description of the query variable
• required: whether the query parameter is mandatory (boolean)
• schema: JSON schema (inline or file)

cookieParams:
  - name: "sessionId"
    description: "The sessionId parameter"
    required: true
    schema:
      type: "string"

requestModels

The requestModels property allows you to define models for the HTTP Request of the function event. You can define a different model for each different Content-Type. You can define a reference to the relevant request model named in the models section of your configuration (see Defining Models section).

requestModels:
  application/json: "CreateRequest"
  application/xml: "CreateRequestXML"

methodResponses

You can define the response schemas by defining properties for your function event.

For an example of a methodResponses configuration for an event see below:

methodResponse:
  - statusCode: 200
    responseHeaders:
      - name: "Content-Type"
        description: "Content Type header"
        schema:
          type: "string"
    responseModels:
      application/json: "CreateResponse"
      application/xml: "CreateResponseXML"

responseModels

The responseModels property allows you to define models for the HTTP Response of the function event. You can define a different model for each different Content-Type. You can define a reference to the relevant response model named in the models section of your configuration (see Defining Models section).

responseModels:
  application/json: "CreateResponse"
  application/xml: "CreateResponseXML"

responseHeaders and requestHeaders

The responseHeaders/requestHeaders section of the configuration allows you to define the HTTP headers for the function event.

The attributes for a header are as follow:

• name: the name of the HTTP Header
• description: a description of the HTTP Header
• schema: JSON schema (inline or file)

responseHeaders:
  - name: "Content-Type"
    description: "Content Type header"
    schema:
      type: "string"
requestHeaders:
  - name: "Content-Type"
    description: "Content Type header"
    schema:
      type: "string"

Example configuration

Please view the example serverless.yml.

Install

This plugin works for Serverless 1.x and up. Serverless 0.5 is not supported.

To add this plugin to your package.json:

Using npm:

npm install @finn.auto/sls-openapi-doc-generator --save-dev

Using Yarn:

yarn add @finn.auto/sls-openapi-doc-generator --dev

Next you need to add the plugin to the plugins section of your serverless.yml file.

plugins:
  - @finn.auto/sls-openapi-doc-generator

It should return ServerlessOpenAPIDocumentation as one of the plugins on the list.

Note: Add this plugin after serverless-offline to prevent issues with String.replaceAll being overridden incorrectly.

Test

All you need to do is to run the following command

yarn test:docjson

check if the command was executed without any errors and the result looks the way you want it. Test case runs automatically on the test/css folder, thus in case you want to include your own project both prepareTests.bash script and test:docjson need to be adjusted accordingly.

To see the generated docs preview on localhost run

cd test/css && sls offline && cd ../..

License

MIT