Serverless OpenAPI TypeScript Plugin

Generates OpenAPI 3.1.0 documentation from serverless configuration files including fully generated request/response models from TypeScript.

This is an extension plugin to the most excellent @conqa/serverless-openapi-documentation.

Partilly works with ReDoc as they're still working on OpenAPI 3.1.0 support.
Works well with Stoplight.io

Why OpenAPI 3.1.0 and not 3.0.0?
Because types generated from TypeScript are complex and require at least json-schema draft07 to be described properly.
OpenAPI 3.1.0 is the first version to be fully compatible with JSON Schema - 3.0.0 is just an "extended subset" of draft05

---

• Usage
  • Options
  • Configuration
    • Models
    • Functions
    • queryParams
    • pathParams
    • cookieParams
    • requestModels
    • methodResponses
    • webhooks
• 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 @conqa/serverless-openapi-documentation and needs to be 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: {}
    typescriptApiPath: 'api.d.ts'
    tsconfigPath: 'tsconfig.json'

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

custom:
  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

These will be generated for you from TypeScript.
For information on how to specify these yourself, see Models on the base plugin page.

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.

This plugin will assert the documentation attribute is set on every non private: true function with an http event.

If you wish a function to not be listed on your documentation, you must explicitly set documentation: ~ to disable docs on that function.

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) - these will be autogenerated for you from TypeScript
• queryParams: a list of query parameters (see queryParams below) - these can be autogenerated for you from TypeScript
• pathParams: a list of path parameters (see pathParams below) - these can be autogenerated for you from TypeScript
• cookieParams: a list of cookie parameters (see cookieParams below)
• methodResponses: an array of response models and applicable status codes (see methodResponses) - these will be autogenerated for you from TypeScript
• webhooks: an object with all the webhooks with descriptions (see webhooks) - these will be autogenerated for you from TypeScript

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) or a string representing fully qualified TypeScript type to generate schema from

Note: If schema is not specified one will be autogenerated for you as { "type": "string" } if you specify querystrings in your Serverless request parameters

Explicit schema example

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

Autogenerated Schema from Serverless config

functions:
  foo:
    events:
      - http:
          request:
            parameters:
              querystrings:
                filter: true

# This will be autogenerated for you based on your Serverless config above! No need to write it yourself:                
# queryParams:
#  - name: "filter"
#    required: true 
#    schema:
#      type: "string"

Generated Schema from TypeScript type

export namespace MyApi {
    export namespace FooBar {
        export namespace Request {
            export namespace QueryParams {
                // You may use JSdoc to set JSON Schema attributes! 
                /** @description The filter parameter **/
                export type Filter = 'hello' | 'world';
            }
        }
    }
}

functions:
  fooBar:
    events:
      - http:
          documentation:
            queryParams:
              - name: "filter"
                schema: "MyApi.FooBar.Request.QueryParams.Filter"
          request:
            parameters:
              querystrings:
                filter: false

# This will be autogenerated for you based from TypeScript! No need to write it yourself                
# queryParams:
#  - name: "filter"
#    required: false
#    description: "The filter parameter"  
#    schema:
#      type: string
#      enum:
#        - hello
#        - world

pathParams

Path parameters can be described as follow:

• name: the name of the query variable
• description: a description of the query variable
• schema: JSON schema (inline or file) or a string representing fully qualified TypeScript type to generate schema from

Explicit schema example

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

Autogenerated Schema from Serverless config

functions:
  foo:
    events:
      - http:
          request:
            parameters:
              pahts:
                usernameId: true

# This will be autogenerated for you based on your Serverless config above! No need to write it yourself:                
# queryParams:
#  - name: "filter"
#    required: true 
#    schema:
#      type: "string"

Generated Schema from TypeScript type

export namespace MyApi {
    export namespace FooBar {
        export namespace Request {
            export namespace PathParams {
                // You may use JSdoc to set JSON Schema attributes! 
                /** @description The usernameId parameter **/
                export type UsernameId = string;
            }
        }
    }
}

functions:
  fooBar:
    events:
      - http:
          documentation:
            paths:
              - name: "usernameId"
                schema: "MyApi.FooBar.Request.QueryParams.Filter"
          request:
            parameters:
              paths:
                usernameId: true

# This will be autogenerated for you based from TypeScript! No need to write it yourself                
# queryParams:
#  - name: "filter"
#    required: true 
#    description: "The usernameId parameter"
#    schema:
#      type: string

cookieParams

TypeScript generation for these isn't supported.
For information on how to specify these yourself, see Cookie Parameters on the base plugin page.

requestModels

The requestModels property allows you to define models for the HTTP Request of the function event.

These will be autogenerated for you from TypeScript by convention.
The plugin will autogenerate a request model for every put, patch or post method based on the TypeScript type found by convention.
The look strategy will be by:
${serverless.custom.documentation.apiNamespace}.${upper-case-name-of-function}.Request.Body. Note that any underscores (_) or hyphens (-) in function names will be excluded in the resolved type (e.g. the Serverless function my_get-function will resolve to MyGetFunction in Typescript)

For example, the following function:

functions:
  myFunction: 
    events:
      - http:
        documentation:
          summary: "Does a lot for you"

Will look for the resolve type as its request model:

// api.d.ts

export namespace MyApi {
    export namespace MyFunction {
        export namespace Request {
            export type Body = {
                id: string,
                name: string,
                age: number
                // ...
            }
        }
    }
}

methodResponses and responseModels

These will be autogenerated for you from TypeScript by convention.
The plugin will autogenerate a response model for every put, patch, post and get method based on the TypeScript type found by convention.
The response will use the generated type as body, and will have a 200 status code.
delete method will be generated with an empty body and 204 status code.
Only application/json response types are supported.

The look strategy will be by:
${serverless.custom.documentation.apiNamespace}.${upper-case-name-of-function}.Response

For example, the following function:

functions:
  myFunction: 
    events:
      - http:
        documentation:
          summary: "Does a lot for you"

Will look for the resolve type as its request model:

// api.d.ts

export namespace MyApi {
  export namespace MyFunction {
    export type Response = {
      id: string,
      name: string,
      age: number
      // ...
    }
  }
}

responseHeaders and requestHeaders

The responseHeaders/requestHeaders section of the configuration allows you to define the HTTP headers for the function event.
TypeScript generation for these isn't supported.
For information on how to specify these yourself, see Response Headers on the base plugin page.

customTags

In some cases where a single serverless.yml contains endpoints which can be grouped differently, you can define custom tags as following:

custom:
  documentation:
    title: 'Project'
    description: DummyDescription

    apiNamespace: ProjectApi
    tags:
       - name: FooBarTitle
         description: FooBarDescription
       - name: BazTitle
         description: BazDescription

functions:
  createFunc:
    handler: handler.create
    events:
      - http:
          documentation:
            summary: "Create Function"
            tag: FooBarTitle

Endpoints that are not attached to a custom tag, are still attached to the title ( which is the default tag ).

webhooks

OpenAPI have an option to add your application webhooks, while this feature isn't supported by serverless.

For those the plugin will look for the webhooks under custom.documentation.webhooks.

For example

custom:
  documentation:
    apiNamespace: MyApi
    webhooks:
      WebhookName:
        post:
          requestBody:
            description: |
              This is a request body description
          responses:
            200:
              description: |
                This is a expected response description

this will generate the next OpenAPI file

components:
  schemas:
    MyApi.Webhooks.WebhookName:
      type: object
webhooks:
  WebhookName:
    post:
      requestBody:
        description: |
          This is a request body description
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/MyApi.Webhooks.WebhookName'
      responses:
        '200':
          description: |
            This is a expected response description

With the next api.d.ts:

export namespace MyApi {
  export namespace Webhooks {
    export type WebhookName = {
      id: string,
      name: string,
      age: number
      // ...
    }
  }
}

Install

This plugin is an extension.
It means you must install and enable @conqa/serverless-openapi-documentation too.

To add these plugins to your package.json:

Using npm:

npm install @conqa/serverless-openapi-documentation --save-dev
npm install serverless-openapi-typescript --save-dev

Using Yarn:

yarn add @conqa/serverless-openapi-documentation --dev
yarn add serverless-openapi-typescript --dev

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

plugins:
  - @conqa/serverless-openapi-documentation
  - serverless-openapi-typescript
  # NOTE: Order is important here - this plugin must be added after the base @conqa/serverless-openapi-documentation plugin
  # This plugin asserts that - you will get a validation message if you get the ordering wrong 

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

License

MIT