aws-cdk.aws-apigateway 0.35.0

The CDK Construct Library for AWS::ApiGateway

Amazon API Gateway Construct Library

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This is a developer preview (public beta) module. Releases might lack important features and might have future breaking changes.

This API is still under active development and subject to non-backward compatible changes or removal in any future version. Use of the API is not recommended in production environments. Experimental APIs are not subject to the Semantic Versioning model.

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Amazon API Gateway is a fully managed service that makes it easy for developers to publish, maintain, monitor, and secure APIs at any scale. Create an API to access data, business logic, or functionality from your back-end services, such as applications running on Amazon Elastic Compute Cloud (Amazon EC2), code running on AWS Lambda, or any web application.

Defining APIs

APIs are defined as a hierarchy of resources and methods. addResource and addMethod can be used to build this hierarchy. The root resource is api.root.

For example, the following code defines an API that includes the following HTTP endpoints: ANY /, GET /books, POST /books, GET /books/{book_id}, DELETE /books/{book_id}.

const api = new apigateway.RestApi(this, 'books-api');

api.root.addMethod('ANY');

const books = api.root.addResource('books');
books.addMethod('GET');
books.addMethod('POST');

const book = books.addResource('{book_id}');
book.addMethod('GET');
book.addMethod('DELETE');

AWS Lambda-backed APIs

A very common practice is to use Amazon API Gateway with AWS Lambda as the backend integration. The LambdaRestApi construct makes it easy:

The following code defines a REST API that routes all requests to the specified AWS Lambda function:

const backend = new lambda.Function(...);
new apigateway.LambdaRestApi(this, 'myapi', {
  handler: backend,
});

You can also supply proxy: false, in which case you will have to explicitly define the API model:

const backend = new lambda.Function(...);
const api = new apigateway.LambdaRestApi(this, 'myapi', {
  handler: backend,
  proxy: false
});

const items = api.root.addResource('items');
items.addMethod('GET');  // GET /items
items.addMethod('POST'); // POST /items

const item = items.addResource('{item}');
item.addMethod('GET');   // GET /items/{item}

// the default integration for methods is "handler", but one can
// customize this behavior per method or even a sub path.
item.addMethod('DELETE', new apigateway.HttpIntegration('http://amazon.com'));

Integration Targets

Methods are associated with backend integrations, which are invoked when this method is called. API Gateway supports the following integrations:

• MockIntegration - can be used to test APIs. This is the default integration if one is not specified.
• LambdaIntegration - can be used to invoke an AWS Lambda function.
• AwsIntegration - can be used to invoke arbitrary AWS service APIs.
• HttpIntegration - can be used to invoke HTTP endpoints.

The following example shows how to integrate the GET /book/{book_id} method to an AWS Lambda function:

const getBookHandler = new lambda.Function(...);
const getBookIntegration = new apigateway.LambdaIntegration(getBookHandler);
book.addMethod('GET', getBookIntegration);

Integration options can be optionally be specified:

const getBookIntegration = new apigateway.LambdaIntegration(getBookHandler, {
  contentHandling: apigateway.ContentHandling.ConvertToText, // convert to base64
  credentialsPassthrough: true, // use caller identity to invoke the function
});

Method options can optionally be specified when adding methods:

book.addMethod('GET', getBookIntegration, {
  authorizationType: apigateway.AuthorizationType.IAM,
  apiKeyRequired: true
});

The following example shows how to use an API Key with a usage plan:

const hello = new lambda.Function(this, 'hello', {
  runtime: lambda.Runtime.NodeJS810,
  handler: 'hello.handler',
  code: lambda.Code.asset('lambda')
});

const api = new apigateway.RestApi(this, 'hello-api', { });
const integration = new apigateway.LambdaIntegration(hello);

const v1 = api.root.addResource('v1');
const echo = v1.addResource('echo');
const echoMethod = echo.addMethod('GET', integration, { apiKeyRequired: true });
const key = api.addApiKey('ApiKey');

const plan = api.addUsagePlan('UsagePlan', {
  name: 'Easy',
  apiKey: key
});

plan.addApiStage({
  stage: api.deploymentStage,
  throttle: [
    {
      method: echoMethod,
      throttle: {
        rateLimit: 10,
        burstLimit: 2
      }
    }
  ]
});

Default Integration and Method Options

The defaultIntegration and defaultMethodOptions properties can be used to configure a default integration at any resource level. These options will be used when defining method under this resource (recursively) with undefined integration or options.

If not defined, the default integration is MockIntegration. See reference documentation for default method options.

The following example defines the booksBackend integration as a default integration. This means that all API methods that do not explicitly define an integration will be routed to this AWS Lambda function.

const booksBackend = new apigateway.LambdaIntegration(...);
const api = new apigateway.RestApi(this, 'books', {
  defaultIntegration: booksBackend
});

const books = new api.root.addResource('books');
books.addMethod('GET');  // integrated with `booksBackend`
books.addMethod('POST'); // integrated with `booksBackend`

const book = books.addResource('{book_id}');
book.addMethod('GET');   // integrated with `booksBackend`

Proxy Routes

The addProxy method can be used to install a greedy {proxy+} resource on a path. By default, this also installs an "ANY" method:

const proxy = resource.addProxy({
  defaultIntegration: new LambdaIntegration(handler),

  // "false" will require explicitly adding methods on the `proxy` resource
  anyMethod: true // "true" is the default
});

Deployments

By default, the RestApi construct will automatically create an API Gateway Deployment and a "prod" Stage which represent the API configuration you defined in your CDK app. This means that when you deploy your app, your API will be have open access from the internet via the stage URL.

The URL of your API can be obtained from the attribute restApi.url, and is also exported as an Output from your stack, so it's printed when you cdk deploy your app:

$ cdk deploy
...
books.booksapiEndpointE230E8D5 = https://6lyktd4lpk.execute-api.us-east-1.amazonaws.com/prod/

To disable this behavior, you can set { deploy: false } when creating your API. This means that the API will not be deployed and a stage will not be created for it. You will need to manually define a apigateway.Deployment and apigateway.Stage resources.

Use the deployOptions property to customize the deployment options of your API.

The following example will configure API Gateway to emit logs and data traces to AWS CloudWatch for all API calls:

By default, an IAM role will be created and associated with API Gateway to allow it to write logs and metrics to AWS CloudWatch unless cloudWatchRole is set to false.

const api = new apigateway.RestApi(this, 'books', {
  deployOptions: {
    loggingLevel: apigateway.MethodLoggingLevel.Info,
    dataTraceEnabled: true
  }
})

Deeper dive: invalidation of deployments

API Gateway deployments are an immutable snapshot of the API. This means that we want to automatically create a new deployment resource every time the API model defined in our CDK app changes.

In order to achieve that, the AWS CloudFormation logical ID of the AWS::ApiGateway::Deployment resource is dynamically calculated by hashing the API configuration (resources, methods). This means that when the configuration changes (i.e. a resource or method are added, configuration is changed), a new logical ID will be assigned to the deployment resource. This will cause CloudFormation to create a new deployment resource.

By default, old deployments are deleted. You can set retainDeployments: true to allow users revert the stage to an old deployment manually.

Missing Features

See awslabs/aws-cdk#723 for a list of missing features.

Roadmap

• Support defining REST API Models #1695

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This module is part of the AWS Cloud Development Kit project.