_Feedback is appreciated! If you have an idea for how this plugin/library can be improved (or even just a complaint/criticism) then please open an issue._

Serverless Plugin: AWS Api Gateway integration helper

1. Overview
1. Installation & Setup
1. Plugin configuration
1. Usage
1. Command
1. CORS Generator
1. AUTO-MOCK Generator
1. VALIDATION Generator
1. PROXY Manager
1. Configuration Reference
1. Known Issues
1. Stage Deployment
1. Variable Resolving
1. Example
1. Approach to a functional test of schema validation

Overview

The plugin provides the functionality to merge OpenApiSpecification files (formerly known as swagger) with one or multiple YML files containing the the x-amazon-apigateway extensions.
There are several use-cases to keep both information separated, e.g. it is needed to deploy different api gateway integrations depending on a stage environment.

When dealing with functional tests you do not want to test the production environment, but only a mocking response.

The plugin supports YML based OpenApi3 specification files only

Features

- Serverless 3.x Support
- deploy stage dependent x-amazon-apigateway integrations
- separate infrastructure (aws) from openapi specification
- use mock integrations for functional testing
- auto-generating CORS methods, headers and api gateway mocking response
- hook into package & deploy lifeCycle and generate combined openApi files on the fly during deployment
- auto-inject generated openApi file into the Body property of specified API Gateway
- generate mocking responses without specifying x-amazon-apigateway-integration objects
- generate request-validation blocks
- generate all required x-amazon-apigateway-integration objects automatically
- full proxy generation support with [NEW]: feature: PROXY Manager

See the examples folder for a full working example

Installation & Setup

Run npm install in your Serverless project.

$ npm install --save-dev serverless-openapi-integration-helper

Add the plugin to your serverless.yml file

``yml
plugins:
- serverless-openapi-integration-helper
`


Plugin configuration

You can configure the plugin under the key openApiIntegration. See
See Configuration Reference for a list of available options

The value for openApiIntegration must be either a single object or an array of objects.
For an array of objects, the apiResourceName property must be specified in each object to determine
which Aws::ApiGateway::RestApi resource to insert the merged API specification into,
while for a single object it's optional and will default to the first found
Aws::ApiGateway::RestApi resource.

The mapping array must be used to configure where the files containing the x-amazon-apigateway-integration blocks are located.

`yml
openApiIntegration:
package: true #New feature! Hook into the package & deploy process
inputFile: schema.yml
mapping:
- stage: [dev, prod] #multiple stages
path: integrations
- stage: test #single stage
path: mocks
`

In the above example all YML files inside the _integrations_ directory will be processed and merged with the schema.yml file when deploying the dev stage
`shell
serverless deploy --stage=dev
`

To use a different x-amazon-apigateway to perform functional tests (with mocking responses e.g) the directory mock is processed and merged with the schema.yml file when deploying the test stage
`shell
serverless deploy --stage=test
`

Multiple APIs

To handle multiple APIs, supply an array as the value of openApiIntegrations
instead of a single object, and specify the target Aws::ApiGateway::RestApi
resource for each item using the apiResourceName property, and make sure to specify
unique output files by setting outputDirectory and/or outputFile uniquely:

`yml
openApiIntegration:
- package: true
inputFile: schema-1.yml
apiResourceName: Api1
outputFile: api-1.yml
mapping:
- stage: [dev, prod]
path: integrations/api-1
- package: true
inputFile: schema-2.yml
apiResourceName: Api2
outputFile: api-2.yml
mapping:
- stage: [dev, prod]
path: integrations/api-2

...

resources:
Resources:
Api1:
Type: AWS::ApiGateway::RestApi
Properties:
Body: ~ # auto-generated by plugin from schema-1

...

Api2:
Type: AWS::ApiGateway::RestApi
Properties:
Body: ~ # auto-generated by plugin from schema-2

...
`

Usage


You can setup a fully working API GATEWAY with any openApi 3.0 specification file
First create the input file containing the OpenApiSpecification
`yml

./schema.yml

openapi: 3.0.0
info:
description: User Registration
version: 1.0.0
title: UserRegistration
paths:
/api/v1/user:
post:
summary: adds a user
requestBody:
content:
application/json:
schema:
$ref: '#/components/schemas/Customer'
responses:
'201':
description: user created
components:
schemas:
Customer:
type: object
required:
- email_address
- password
properties:
email_address:
type: string
example: test@example.com
password:
type: string
format: password
example: someStrongPassword#
`

The plugin will generate the x-amazon-apigateway integrations objects for all methods that do not have an integration.

`yml
#generate a file containing a gateway mock integration in the directory /mocks
serverless integration create --output mocks --type mock --stage=test

#generate a file containing the production integration in the directory integrations/
serverless integration create --output integrations --type http --stage=prod
`

Supported types are
- http_proxy
- http
- aws
- aws_proxy
- mock


The plugin now generates a merged file during deployment that is automatically injected in your serverless resources

`shell
#Create OpenApi File containing mocking responses (usable in functional tests) and deploy to ApiGateway
serverless deploy --stage==test
`

`shell
#Create OpenApi File containing the production integration and deploy to ApiGateway
serverless deploy --stage=prod
`

The generated output is automatically injected in the resources.Resources.YOUR_API_GATEWAY.Properties.Body property
`yml
resources:
Resources:
ApiGatewayRestApi:
Type: AWS::ApiGateway::RestApi
Properties:
ApiKeySourceType: HEADER
Body: ~ #autogenerated by plugin
Description: "Some Description"
FailOnWarnings: false
Name: ${opt:stage, self:provider.stage}-some-name
EndpointConfiguration:
Types:
- REGIONAL
ApiGatewayDeployment:
Type: AWS::ApiGateway::Deployment
Properties:
RestApiId:
Ref: ApiGatewayRestApi
StageName: ${opt:stage, self:provider.stage}
`

Commands

Manual merge


The generate command can be used independently with
`yml
serverless integration merge --stage=dev
`
Of course then the API Gateway Body property has to be specified manually

`yml
resources:
Resources:
ApiGatewayRestApi:
Type: AWS::ApiGateway::RestApi
Properties:
ApiKeySourceType: HEADER
Body: ${file(openapi-integration/api.yml)}
`

CORS generator

The plugin can generate full CORS support out of the box.
`yml
openApiIntegration:
cors: true
...
`

If enabled, the plugin generates all required OPTIONS methods as well as the required header informations and adds a mocking response to API Gateway.
You can customize the CORS templates by placing your own files inside a directory openapi-integration (in your project root). The following files can be overwritten:

| Filename | Description |
| ------------- |:-------------:|
| headers.yml | All headers required for CORS support |
| integration.yml | Contains the x-amazon-apigateway-integration block |
| path.yml| OpenApi specification for the OPTIONS method |
| response-parameters.yml| The response Parameters of the x-amazon-apigateway-integration responses |

See the EXAMPLES directory for detailed instructions.

Auto Mock Generator


If enabled, the plugin generates mocking responses for all methods that do not have an x-amazon-apigateway-integration block defined.
It takes the first 2xx response defined in the openApi specification and generates a simple mocking response on the fly
`yml
openApiIntegration:
autoMock: true
...
`

When using the autoMock feature, you do not need to specify inputPath mappings, since all endpoints are mocked automatically

`yml
openApiIntegration:
package: true
inputFile: schema.yml
mapping: ~
`

VALIDATION generator

The plugin supports full request validation out of the box
`yml
openApiIntegration:
validation: true
...
`

If enabled, the plugin generates the x-amazon-apigateway-request-validators blocks and adds a basic request validation to all methods.
You can customize the VALIDATION template by placing your own files inside a directory openapi-integration (in your project root). The following files can be overwritten:

| Filename | Description |
| ------------- |:-------------:|
| request-validator.yml | The x-amazon-apigateway-request-validators block |

See the EXAMPLES directory for detailed instructions.

Proxy Manager

The proxymanager feature automates the complete generation of an HTTP proxy integration.
You only have to define the target URL and all necessary AWS integration blocks are generated on-the-fly during deployment.


`yml
openApiIntegration:
cors: true
validation: true
mapping:
- stage: [dev, prod]
proxyManager:
type: http_proxy
baseUrl: https://www.example.com
pattern: "(?<=api\/v1)\/.+"
...
`

With this setting, no separate integration files need to be created

A combination of your own and auto-generated files is still possible without any problems

Proxy Manager configuration

$3

at the moment only http_proxy supported

$3

The base url is required to map the path variable from the openapi specification to the URI from the aws integration.

Example:

`yml
#original openapi specification
paths:
/api/v1/user:
post:
...
`

will be translated to

`yml
#generated openapi specification output
paths:
/api/v1/user:
post:
...
x-amazon-apigateway-integration:
type: http_proxy
passthroughBehavior: when_no_match
httpMethod: POST
uri: https://www.example.com/api/v1/user
`

$3

The pattern can be used to adapt the mapping of the base url using regexp, to remove a prefix, or a version string

Example:

`yml
baseUrl: https://www.example.com
pattern: "(?<=api\/v1)\/.+"
`

will translate the route /api/v1/user to https://www.example.com/user

Configuration Reference

configure the plugin under the key openApiIntegration

`yml
openApiIntegration:
inputFile: schema.yml #required
package: true #optional, defaults to false
inputDirectory: ./ #optional, defaults to ./
cors: true #optional, defaults to false
autoMock: true #optional, defaults to false
validation: true #optional, defaults to false
mapping: #optional, can be completely blank if autoMock option is enabled
- stage: [dev, prod] #multiple stages
path: integrations
proxyManager: #optional
type: http_proxy
baseUrl: https://example.com
pattern: "(?<=v1)\/.+"
- stage: test #single stage
path: mocks/customer.yml
outputFile: api.yml #optional, defaults to api.yml
outputDirectory: openapi-integration #optional, defaults to ./openapi-integration
`

Known Issues

Stage deployment

When using serverless framework only to deploy your aws resources without having any lambda functions or triggers, the AWS Gateway deploymemt does not behave as expected.
Any deployment to an existing stage will be ignored, since CloudFormation does not redeploy a stage if the DeploymentIdentifier has not changed.

The plugin serverless-random-gateway-deployment-id solves this problem by adding a random id to the deployment-name and all references to it on every deploy

See the examples folder for a full working example

Variable Resolving

Serverless variables inside the openapi integration files are not resolved correctly when using the package & deploy hooks. This problem can be solved by using the api gateway STAGE VARIABLES.

See the examples folder for a full working example

Example

`yml
service:
name: user-registration

provider:
name: aws
stage: dev
region: eu-central-1

plugins:
- serverless-openapi-integration-helper

openApiIntegration:
inputFile: schema.yml
package: true
mapping:
- path: integrations
stage: [dev, prod]
- path: mocks/customer.yml
stage: test

functions:

resources:
Resources:
ApiGatewayRestApi:
Type: AWS::ApiGateway::RestApi
Properties:
ApiKeySourceType: HEADER
Body: ~
Description: "Some Description"
FailOnWarnings: false
Name: ${opt:stage, self:provider.stage}-some-name
EndpointConfiguration:
Types:
- REGIONAL
ApiGatewayDeployment:
Type: AWS::ApiGateway::Deployment
Properties:
RestApiId:
Ref: ApiGatewayRestApi
StageName: ${opt:stage, self:provider.stage}
`

`
serverless deploy --stage=test
`

`
serverless deploy --stage=prod
`

Approach to a functional test of schema validation

The plugin works well in combination with the serverless-plugin-test-helper to automate tests against the deployed api gateway

Install The plugin test helper package

`shell
npm install --save-dev serverless-plugin-test-helper
`

add the plugin as a plugin dependency in your serverless configuration file and configure the plugin according to the Readme
`yml
#./serveless.yml
plugins:
- serverless-plugin-test-helper
- serverless-openapi-integration-helper

[...]

resources:
Outputs:
GatewayUrl: # This is the key that will be used in the generated outputs file
Description: This is a helper for functional tests
Value: !Join
- ''
- - 'https://'
- !Ref ApiGatewayRestApi
- '.execute-api.'
- ${opt:region, self:provider.region}
- '.amazonaws.com/'
- ${opt:stage, self:provider.stage}

Resources:
ApiGatewayRestApi:
Type: AWS::ApiGateway::RestApi
Properties:
ApiKeySourceType: HEADER
Body: ~
Description: User Registration (${opt:stage, self:provider.stage})
FailOnWarnings: false
Name: ${opt:stage, self:provider.stage}-gateway
EndpointConfiguration:
Types:
- REGIONAL
ApiGatewayDeployment:
Type: AWS::ApiGateway::Deployment
Properties:
RestApiId:
Ref: ApiGatewayRestApi
StageName: ${opt:stage, self:provider.stage}
`

Testing the schema validation

Add a functional test (e.g. with jest)

`javascript
//tests/registration.js
import {getOutput} from 'serverless-plugin-test-helper';
import axios from 'axios';

axios.defaults.adapter = require('axios/lib/adapters/http'); //Todo

const URL = getOutput('GatewayUrl');
test('request validation on registration', async () => {
expect.assertions(1);
const {status} = await axios.post(URL + '/api/v1/user',
{
"email_address": "test@example.com",
"password": "someStrongPassword#"
},
{
headers: {
'Content-Type': 'application/json',
}
});
expect(status).toEqual(201);
});

test('request validation on registration (invalid request)', async () => {
expect.assertions(1);
try {
await axios.post(URL + '/api/v1/user',
{
"email": "test@example.com"
},
{
headers: {
'Content-Type': 'application/json',
}
});
} catch (e) {
expect(e.response).toMatchObject({
statusText: 'Bad Request',
status: 400
});
}
});
`
Then perform the functional test
`shell
serverless deploy --stage=test
npm test
serverless remove --stage=test
``

The command will
- merge the openapi specification file with the MOCK integration configured before
- deploy to API Gateway in an isolated TEST infrastructure environment (your other environments will not be affected since we are deploying to a separated gateway)
- perform the test and verify that schema validation is correct
- remove all TEST resources if test succeeded

See the examples folder for a full working example