aws-openapigateway-lambda

Reference Documentation:

https://docs.aws.amazon.com/solutions/latest/constructs/

Language	Package
Python	aws_solutions_constructs.aws_openapigateway_lambda
Typescript	@aws-solutions-constructs/aws-openapigateway-lambda
Java	software.amazon.awsconstructs.services.openapigatewaylambda

Overview

This AWS Solutions Construct implements an Amazon API Gateway REST API defined by an OpenAPI specification file connected to an AWS Lambda function.

Here is a minimal deployable pattern definition.

NOTE The referenced openapi/apiDefinition.yaml openapi definition file and messages-lambda lambda package directory for the three code samples below can both be found under this constructs test folder (<repository_root>/source/patterns/@aws-solutions-constructs/aws-openapigateway-lambda/test)

Typescript

import { Stack, StackProps } from 'aws-cdk-lib';
import { Construct } from 'constructs';
import { OpenApiGatewayToLambda } from '@aws-solutions-constructs/aws-openapigateway-lambda';
import { Asset } from 'aws-cdk-lib/aws-s3-assets';
import * as path from 'path';
import * as lambda from 'aws-cdk-lib/aws-lambda';

const apiDefinitionAsset = new Asset(this, 'ApiDefinitionAsset', {
  path: path.join(__dirname, 'openapi/apiDefinition.yaml')
});

new OpenApiGatewayToLambda(this, 'OpenApiGatewayToLambda', {
  apiDefinitionAsset,
  apiIntegrations: [
    {
      id: 'MessagesHandler',
      lambdaFunctionProps: {
        runtime: lambda.Runtime.NODEJS_20_X,
        handler: 'index.handler',
        code: lambda.Code.fromAsset(`${__dirname}/messages-lambda`),
      }
    }
  ]
});

Python

from aws_cdk import (
    Stack,
    aws_s3_assets as s3_assets,
    aws_lambda as lambda_,
)
from constructs import Construct
from aws_solutions_constructs.aws_openapigateway_lambda import OpenApiGatewayToLambda, ApiIntegration

class TestStack(Stack):

    def __init__(self, scope: Construct, construct_id: str, **kwargs) -> None:
        super().__init__(scope, construct_id, **kwargs)

        api_definition_asset = s3_assets.Asset(self, "ApiDefinitionAsset", path="./openapi/apiDefinition.yaml")

        api_integration = ApiIntegration(id="MessagesHandler", lambda_function_props={
            "runtime": lambda_.Runtime.NODEJS_20_X,
            "handler": "index.handler",
            "code": lambda_.Code.from_asset("./messages-lambda")
        })

        openapigateway_to_lambda = OpenApiGatewayToLambda(self,
            id="OpenApiGatewayToLambda",
            api_integrations=[api_integration],
            api_definition_asset=api_definition_asset
        )

Java

import software.amazon.awscdk.services.lambda.Code;
import software.amazon.awscdk.services.lambda.FunctionProps;
import software.amazon.awscdk.services.s3.assets.Asset;
import software.amazon.awscdk.services.s3.assets.AssetProps;
import software.amazon.awsconstructs.services.openapigatewaylambda.ApiIntegration;
import software.amazon.awsconstructs.services.openapigatewaylambda.OpenApiGatewayToLambda;
import software.amazon.awsconstructs.services.openapigatewaylambda.OpenApiGatewayToLambdaProps;
import software.constructs.Construct;
import software.amazon.awscdk.Stack;
import software.amazon.awscdk.StackProps;

import java.util.Collections;

import static software.amazon.awscdk.services.lambda.Runtime.NODEJS_20_X;

final Asset apiDefinitionAsset = new Asset(this, "ApiDefinition", AssetProps.builder().path("openapi/apiDefinition.yaml").build());

final ApiIntegration apiIntegration = ApiIntegration.builder()
    .id("MessagesHandler")
    .lambdaFunctionProps(new FunctionProps.Builder()
        .runtime(NODEJS_20_X)
        .code(Code.fromAsset("messages-lambda"))
        .handler("index.handler")
        .build())
    .build();

new OpenApiGatewayToLambda(this, "OpenApiGatewayToLambda", OpenApiGatewayToLambdaProps.builder()
    .apiDefinitionAsset(apiDefinitionAsset)
    .apiIntegrations(Collections.singletonList(apiIntegration))
    .build());

Pattern Construct Props

Name	Type	Description
apiGatewayProps?	apigateway.RestApiBaseProps	Optional user-provided props to override the default props for the API.
apiDefinitionBucket?	s3.IBucket	S3 Bucket where the OpenAPI spec file is located. When specifying this property, apiDefinitionKey must also be specified.
apiDefinitionKey?	string	S3 Object name of the OpenAPI spec file. When specifying this property, apiDefinitionBucket must also be specified.
apiDefinitionAsset?	aws_s3_assets.Asset	Local file asset of the OpenAPI spec file.
apiDefinitionJson?	any	OpenAPI specification represented in a JSON object to be embedded in the CloudFormation template. IMPORTANT - Including the spec in the template introduces a risk of the template growing too big, but there are some use cases that require an embedded spec. Unless your use case explicitly requires an embedded spec you should pass your spec as an S3 asset.
apiIntegrations	ApiIntegration[]	One or more key-value pairs that contain an id for the api integration and either an existing lambda function or an instance of the LambdaProps. Please see the Overview of how the OpenAPI file transformation works section below for more usage details.
logGroupProps?	logs.LogGroupProps	User provided props to override the default props for for the CloudWatchLogs LogGroup.

Pattern Properties

Name	Type	Description
apiLambdaFunctions	ApiLambdaFunction[]	Returns an array of ApiLambdaFunction objects, where each has an id of the apiIntegration and the corresponding lambda.Function that it maps to.
apiGateway	api.SpecRestApi	Returns an instance of the API Gateway REST API created by the pattern.
apiGatewayCloudWatchRole?	iam.Role	Returns an instance of the iam.Role created by the construct for API Gateway for CloudWatch access.
apiGatewayLogGroup	logs.LogGroup	Returns an instance of the LogGroup created by the construct for API Gateway access logging to CloudWatch.

Interfaces defined by this construct

ApiIntegration Maps a Lambda function to the id string used as a placeholder in the OpenAPI spec. The type has a required property, id, and two optional properties existingLambdaObj, and lambdaFunctionProps. The id property is used to map the corresponding lambda function being defined with the placeholder string in the OpenAPI template file, and is not a CDK construct ID. Exactly one of existingLambdaObj or lambdaFunctionProps must be specified or the construct will throw an error. The existingLambaObj property will accept a lambda.Function object OR a lambda.Alias object. The property ApiIntegrations is an array of this interface and is a required property when launching this construct.

ApiLambdaFunction This interface returns the Lambda objects used when launching the construct. The id property will always be set, if an existing function was provided in the props or this construct created a new Lambda function, then that function will be in the lambdaFunction property. If a Lambda Alias was provided in the props, then that value will be specified in the functionAlias property. At no time will lambdaFunction and functionAlias be set on the same ApiLambdaFunction object. The construct exposes an array of these objects as a property.

Overview of how the OpenAPI file transformation works

This construct automatically transforms an incoming OpenAPI Definition (residing locally or in S3) by auto-populating the uri fields of the x-amazon-apigateway-integration integrations with the resolved value of the backing lambda functions. It does so by allowing the user to specify the apiIntegrations property and then correlates it with the api definition.

Looking at an example - a user creates an instantiation of apiIntegrations that specifies one integration named MessagesHandler that passes in a set of lambda.FunctionProps and a second integration named PhotosHandler that passes in an existing lambda.Function:

const apiIntegrations: ApiIntegration[] = [
  {
    id: 'MessagesHandler',
    lambdaFunctionProps: {
      runtime: lambda.Runtime.NODEJS_20_X,
      handler: 'index.handler',
      code: lambda.Code.fromAsset(`${__dirname}/messages-lambda`),
    }
  },
  {
    id: 'PhotosHandler',
    existingLambdaObj: new lambda.Function(this, 'PhotosLambda', {
      runtime: lambda.Runtime.NODEJS_20_X,
      handler: 'index.handler',
      code: lambda.Code.fromAsset(`${__dirname}/photos-lambda`),
    })
  }
]

And a corresponding api definition with GET and POST methods on a /messages resource and a GET method on a /photos resource.

openapi: "3.0.1"
info:
  title: "api"
  version: "2023-02-20T20:46:08Z"
paths:
  /messages:
    get:
      x-amazon-apigateway-integration:
        httpMethod: "POST"
        uri: MessagesHandler
        passthroughBehavior: "when_no_match"
        type: "aws_proxy"
    post:
      x-amazon-apigateway-integration:
        httpMethod: "POST"
        uri: MessagesHandler
        passthroughBehavior: "when_no_match"
        type: "aws_proxy"
  /photos:
    get:
      x-amazon-apigateway-integration:
        httpMethod: "POST"
        uri: PhotosHandler
        passthroughBehavior: "when_no_match"
        type: "aws_proxy"

When the construct is created or updated, it will overwrite the MessagesHandler string with the fully resolved lambda proxy uri of the MessagesHandlerLambdaFunction, e.g., arn:${Aws.PARTITION}:apigateway:${Aws.REGION}:lambda:path/2015-03-31/functions/${messagesLambda.functionArn}/invocations, and similarly for the PhotosHandler string and PhotosHandlerLambdaFunction, resulting in a valid OpenAPI spec file that is then passed to the SpecRestApi construct.

For more information on specifying an API with OpenAPI, please see the OpenAPI Specification

Default settings

Out of the box implementation of the Construct without any override will set the following defaults:

Amazon API Gateway

• Deploy an edge-optimized API endpoint

• Enable CloudWatch logging for API Gateway

• Configure least privilege access IAM role for API Gateway

• Enable X-Ray Tracing

AWS Lambda Function

• Configure limited privilege access IAM roles for Lambda functions

• Enable reusing connections with Keep-Alive for NodeJs Lambda functions

• Enable X-Ray Tracing

• Set Environment Variables

  • AWS_NODEJS_CONNECTION_REUSE_ENABLED (for Node 10.x and higher functions)

Architecture

Github

Go to the Github repo for this pattern to view the code, read/create issues and pull requests and more.