AWS APIGatewayv2 Integrations

Table of Contents

• HTTP APIs

  • Lambda Integration
  • HTTP Proxy Integration
  • Private Integration
  • Request Parameters

• WebSocket APIs

  • Lambda WebSocket Integration

HTTP APIs

Integrations connect a route to backend resources. HTTP APIs support Lambda proxy, AWS service, and HTTP proxy integrations. HTTP proxy integrations are also known as private integrations.

Lambda

Lambda integrations enable integrating an HTTP API route with a Lambda function. When a client invokes the route, the API Gateway service forwards the request to the Lambda function and returns the function's response to the client.

The API Gateway service will invoke the lambda function with an event payload of a specific format. The service expects the function to respond in a specific format. The details on this format is available at Working with AWS Lambda proxy integrations.

The following code configures a route GET /books with a Lambda proxy integration.

import "github.com/aws/aws-cdk-go/awscdk"

var booksDefaultFn function

booksIntegration := awscdk.NewHttpLambdaIntegration(jsii.String("BooksIntegration"), booksDefaultFn)

httpApi := apigwv2.NewHttpApi(this, jsii.String("HttpApi"))

httpApi.AddRoutes(&AddRoutesOptions{
	Path: jsii.String("/books"),
	Methods: []httpMethod{
		apigwv2.*httpMethod_GET,
	},
	Integration: booksIntegration,
})

HTTP Proxy

HTTP Proxy integrations enables connecting an HTTP API route to a publicly routable HTTP endpoint. When a client invokes the route, the API Gateway service forwards the entire request and response between the API Gateway endpoint and the integrating HTTP endpoint. More information can be found at Working with HTTP proxy integrations.

The following code configures a route GET /books with an HTTP proxy integration to an HTTP endpoint get-books-proxy.myproxy.internal.

import "github.com/aws/aws-cdk-go/awscdk"


booksIntegration := awscdk.NewHttpUrlIntegration(jsii.String("BooksIntegration"), jsii.String("https://get-books-proxy.myproxy.internal"))

httpApi := apigwv2.NewHttpApi(this, jsii.String("HttpApi"))

httpApi.AddRoutes(&AddRoutesOptions{
	Path: jsii.String("/books"),
	Methods: []httpMethod{
		apigwv2.*httpMethod_GET,
	},
	Integration: booksIntegration,
})

Private Integration

Private integrations enable integrating an HTTP API route with private resources in a VPC, such as Application Load Balancers or Amazon ECS container-based applications. Using private integrations, resources in a VPC can be exposed for access by clients outside of the VPC.

The following integrations are supported for private resources in a VPC.

Application Load Balancer

The following code is a basic application load balancer private integration of HTTP API:

import "github.com/aws/aws-cdk-go/awscdk"


vpc := ec2.NewVpc(this, jsii.String("VPC"))
lb := elbv2.NewApplicationLoadBalancer(this, jsii.String("lb"), &ApplicationLoadBalancerProps{
	Vpc: Vpc,
})
listener := lb.AddListener(jsii.String("listener"), &BaseApplicationListenerProps{
	Port: jsii.Number(80),
})
listener.AddTargets(jsii.String("target"), &AddApplicationTargetsProps{
	Port: jsii.Number(80),
})

httpEndpoint := apigwv2.NewHttpApi(this, jsii.String("HttpProxyPrivateApi"), &HttpApiProps{
	DefaultIntegration: awscdk.NewHttpAlbIntegration(jsii.String("DefaultIntegration"), listener),
})

When an imported load balancer is used, the vpc option must be specified for HttpAlbIntegration.

Network Load Balancer

The following code is a basic network load balancer private integration of HTTP API:

import "github.com/aws/aws-cdk-go/awscdk"


vpc := ec2.NewVpc(this, jsii.String("VPC"))
lb := elbv2.NewNetworkLoadBalancer(this, jsii.String("lb"), &NetworkLoadBalancerProps{
	Vpc: Vpc,
})
listener := lb.AddListener(jsii.String("listener"), &BaseNetworkListenerProps{
	Port: jsii.Number(80),
})
listener.AddTargets(jsii.String("target"), &AddNetworkTargetsProps{
	Port: jsii.Number(80),
})

httpEndpoint := apigwv2.NewHttpApi(this, jsii.String("HttpProxyPrivateApi"), &HttpApiProps{
	DefaultIntegration: awscdk.NewHttpNlbIntegration(jsii.String("DefaultIntegration"), listener),
})

When an imported load balancer is used, the vpc option must be specified for HttpNlbIntegration.

Cloud Map Service Discovery

The following code is a basic discovery service private integration of HTTP API:

import servicediscovery "github.com/aws/aws-cdk-go/awscdk"
import "github.com/aws/aws-cdk-go/awscdk"


vpc := ec2.NewVpc(this, jsii.String("VPC"))
vpcLink := apigwv2.NewVpcLink(this, jsii.String("VpcLink"), &VpcLinkProps{
	Vpc: Vpc,
})
namespace := servicediscovery.NewPrivateDnsNamespace(this, jsii.String("Namespace"), &PrivateDnsNamespaceProps{
	Name: jsii.String("boobar.com"),
	Vpc: Vpc,
})
service := namespace.CreateService(jsii.String("Service"))

httpEndpoint := apigwv2.NewHttpApi(this, jsii.String("HttpProxyPrivateApi"), &HttpApiProps{
	DefaultIntegration: awscdk.NewHttpServiceDiscoveryIntegration(jsii.String("DefaultIntegration"), service, &HttpServiceDiscoveryIntegrationProps{
		VpcLink: *VpcLink,
	}),
})

Request Parameters

Request parameter mapping allows API requests from clients to be modified before they reach backend integrations. Parameter mapping can be used to specify modifications to request parameters. See Transforming API requests and responses.

The following example creates a new header - header2 - as a copy of header1 and removes header1.

import "github.com/aws/aws-cdk-go/awscdk"

var lb applicationLoadBalancer

listener := lb.AddListener(jsii.String("listener"), &BaseApplicationListenerProps{
	Port: jsii.Number(80),
})
listener.AddTargets(jsii.String("target"), &AddApplicationTargetsProps{
	Port: jsii.Number(80),
})

httpEndpoint := apigwv2.NewHttpApi(this, jsii.String("HttpProxyPrivateApi"), &HttpApiProps{
	DefaultIntegration: awscdk.NewHttpAlbIntegration(jsii.String("DefaultIntegration"), listener, &HttpAlbIntegrationProps{
		ParameterMapping: apigwv2.NewParameterMapping().AppendHeader(jsii.String("header2"), apigwv2.MappingValue_RequestHeader(jsii.String("header1"))).RemoveHeader(jsii.String("header1")),
	}),
})

To add mapping keys and values not yet supported by the CDK, use the custom() method:

import "github.com/aws/aws-cdk-go/awscdk"

var lb applicationLoadBalancer

listener := lb.AddListener(jsii.String("listener"), &BaseApplicationListenerProps{
	Port: jsii.Number(80),
})
listener.AddTargets(jsii.String("target"), &AddApplicationTargetsProps{
	Port: jsii.Number(80),
})

httpEndpoint := apigwv2.NewHttpApi(this, jsii.String("HttpProxyPrivateApi"), &HttpApiProps{
	DefaultIntegration: awscdk.NewHttpAlbIntegration(jsii.String("DefaultIntegration"), listener, &HttpAlbIntegrationProps{
		ParameterMapping: apigwv2.NewParameterMapping().Custom(jsii.String("myKey"), jsii.String("myValue")),
	}),
})

WebSocket APIs

WebSocket integrations connect a route to backend resources. The following integrations are supported in the CDK.

Lambda WebSocket Integration

Lambda integrations enable integrating a WebSocket API route with a Lambda function. When a client connects/disconnects or sends message specific to a route, the API Gateway service forwards the request to the Lambda function

The API Gateway service will invoke the lambda function with an event payload of a specific format.

The following code configures a sendmessage route with a Lambda integration

import "github.com/aws/aws-cdk-go/awscdk"

var messageHandler function


webSocketApi := apigwv2.NewWebSocketApi(this, jsii.String("mywsapi"))
apigwv2.NewWebSocketStage(this, jsii.String("mystage"), &WebSocketStageProps{
	WebSocketApi: WebSocketApi,
	StageName: jsii.String("dev"),
	AutoDeploy: jsii.Boolean(true),
})
webSocketApi.AddRoute(jsii.String("sendmessage"), &WebSocketRouteOptions{
	Integration: awscdk.NewWebSocketLambdaIntegration(jsii.String("SendMessageIntegration"), messageHandler),
})