Amazon API Gateway, AWS Lambda and Amazon DynamoDB with Lambda SnapStart for Java

This pattern demonstrates how to create a synchronous REST API using API Gateway, AWS Lambda and DynamoDB. This pattern is built using Spring Boot 3 and leverages the AWS Serverless Java Container for seamless integration with AWS Lambda. This pattern also demonstrates the usage of SnapStart to improve startup performance.

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

Spring Web support in Lambda

This pattern uses the Spring Web @Controller to support different REST endpoints in the same Lambda function. There are two supported ways to achieve this with the AWS Serverless Java Container.

Delegating the handler to Spring

The first is to specify a Spring class as the function handler and reference the SpringBootApplication class as an environment variable.

    Type: AWS::Serverless::Function
    Properties:
      Handler: com.amazonaws.serverless.proxy.spring.SpringDelegatingLambdaContainerHandler
      ...
      Environment:
         Variables:
            MAIN_CLASS: com.unicorn.store.StoreApplication

This is useful as you don't need to make any changes to your existing application to run it in Lambda.

Starting Spring in your own handler

An alternative is to create your own handler and start Spring within it. The class StreamLambdaHandler is an example of this.

This is useful when you want control over the handler method, for example to add an annotation.

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 Serverless Application Model (AWS SAM) installed
• Java 17
• Maven
• CURL
• jq

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 apigw-lambda-snapstart
   

3. Build the function

   sam build
   

4. Deploy the infrastructure

   sam deploy --stack-name unicorn-store --guided
   

Testing

To test the Lambda function you can POST a unicorn JSON payload to the '/unicorns' endpoint.

curl --location --request POST $(aws cloudformation describe-stacks --stack-name unicorn-store --query "Stacks[0].Outputs[?OutputKey=='UnicornEndpoint'].OutputValue" --output text)'/unicorns' \
--header 'Content-Type: application/json' \
--data-raw '{
"name": "Something",
"age": "Older",
"type": "Animal",
"size": "Very big"
}' | jq

Measuring the results

You can use the following AWS CloudWatch Insights query to measure the duration your SnapStart Lambda function.

filter @message like "REPORT"
| filter @message not like "RESTORE_REPORT"
| parse @message /Restore Duration: (?<@restore_duration_ms>[0-9\.]+)/
| parse @message /	Duration: (?<@invoke_duration_ms>[0-9\.]+)/
| fields
  greatest(@restore_duration_ms, 0) as restore_duration_ms,
  greatest(@invoke_duration_ms, 0) as invoke_duration_ms
| fields
  restore_duration_ms + invoke_duration_ms as total_invoke_ms
| stat
  pct(total_invoke_ms, 50) as total_invoke_ms_p50,
  pct(total_invoke_ms, 99) as total_invoke_ms_p99,
  pct(total_invoke_ms, 99.9) as total_invoke_ms_p99.9