Amazon API Gateway to AWS Fargate

This project contains a sample AWS Cloud Development Kit (AWS CDK) template for deploying an AWS Fargate service running on an Amazon Elastic Container Service (ECS) cluster with a private Application Load Balancer in-front. The Application Load Balanced Fargate Service is integrated with Amazon API Gateway HTTP API to expose the endpoint. This template uses a custom image without having to pre-push the image to Amazon Elastic Container Registry (ECR) or another container library. This makes use of the in-built ecs.ContainerImage.fromAsset method. The custom image has a base route / to output a message.

Learn more about this pattern at Serverless Land Patterns: https://serverlessland.com/patterns/apigw-fargate-cdk.

Important: this application uses various AWS services and there are costs associated with these services after the Free Tier usage – please see the AWS Pricing page for details. You are responsible for any AWS costs incurred. No warranty is implied in this example.

Warning: As of this writing, there are known issues with the images built on Apple’s M1 chip, which is based on the ARM architecture. You might encounter the following error log on ECS standard_init_linux.go:228: exec user process caused: exec format error fargate. More details can be found at Stackoverflow ‘exec user process caused: exec format error’ in AWS Fargate Service

Requirements

• Create an AWS account if you do not already have one and log in. The IAM user that you use must have sufficient permissions to make necessary AWS service calls and manage AWS resources.
• AWS CLI installed and configured
• Git Installed
• AWS CDK installed and configured

Deployment Instructions

1. Create a new directory, navigate to that directory in a terminal and clone the GitHub repository:

   git clone https://github.com/aws-samples/serverless-patterns
   

2. Change directory to the pattern directory:

   cd serverless-patterns/apigw-fargate-cdk/cdk
   

3. Install dependencies:

   npminstall

4. From the command line, configure AWS CDK:

   cdk bootstrap ACCOUNT-NUMBER/REGION # e.g.
   cdk bootstrap 1111111111/us-east-1
   cdk bootstrap --profile test1111111111/us-east-1
   

5. Ensure that the bucket name is unique in cdk-stack.ts
6. From the command line, use AWS CDK to deploy the AWS resources for the pattern as specified in the lib/cdk-stack.ts file:

   cdk deploy
   

7. Note the outputs from the CDK deployment process. This contains the apigw endpoint that is used to make the GET request

How it works

• The image is constructed directly from sources on disk when cdk deploy is executed
• The image is automatically pushed to Amazon ECR
• The VPC and subnets are created
• The ECS cluster is created
• The Task Definitions are created
• The API Gateway Integration, Route, and VPC Link are created
• The Fargate Service is created

Testing

Retrieve the API Gateway URL from the cdk deploy output. Example of the output is:

CdkStack.APIGatewayUrl = https://abcd123efg.execute-api.ap-southeast-2.amazonaws.com/

For reference:

<img src=”./docs/01-cdk-deploy-output.png” alt=”cdk-deploy-output” width=”90%”/>

The API Gateway allows a GET request to /. To call it, run the following:

curl --location --request GET '<REPLACE WITH API GATEWAY URL>'# Examplecurl --location --request GET 'https://abcd123efg.execute-api.ap-southeast-2.amazonaws.com/'

Running the request above should produce the following output:

<img src=”./docs/02-example-request.png” alt=”example-request” width=”90%”/>

Cleanup

1. Delete the stack

   cdk destroy
   

2. Navigate to ECR in the AWS console and delete the container images created

Documentation and useful references

• GitHub issue where one of the contributors provided an example with a pre-built image and any type of request
• CDK documentation for ApplicationLoadBalancedFargateService
• CDK documentation for APIGatewayv2 CfnIntegration
• CDK documentation for APIGatewayv2 CfnRoute
• CDK documentation for APIGatewayv2 HttpApi
• CDK documentation for CDK Core CfnResource