Lambda Invoker

The lambda-invoker module provides a way to invoke AWS Lambda functions from a light-4j application. It includes a configuration class and an HTTP handler that can be used to proxy requests to Lambda functions.

Core Components

LambdaInvokerConfig

The configuration class for the Lambda invoker. It loads settings from lambda-invoker.yml.

• region: The AWS region where the Lambda functions are deployed.
• endpointOverride: Optional URL to override the default AWS Lambda endpoint.
• apiCallTimeout: Timeout for the entire API call in milliseconds.
• apiCallAttemptTimeout: Timeout for each individual API call attempt in milliseconds.
• maxRetries: Maximum number of retries for the invocation.
• maxConcurrency: Maximum number of concurrent requests to Lambda.
• functions: A map of endpoints to Lambda function names or ARNs.
• metricsInjection: Whether to inject Lambda response time metrics into the metrics handler.

LambdaFunctionHandler

An HTTP handler that proxies requests to AWS Lambda functions based on the configured mapping.

• Behavior: It converts the incoming HttpServerExchange into an APIGatewayProxyRequestEvent, invokes the configured Lambda function asynchronously using the LambdaAsyncClient, and then converts the APIGatewayProxyResponseEvent back into the HTTP response.
• Metrics: If enabled, it records the total time spent in the Lambda invocation and injects it into the metrics handler.

Configuration

Example lambda-invoker.yml:

region: us-east-1
apiCallTimeout: 60000
apiCallAttemptTimeout: 20000
maxRetries: 2
maxConcurrency: 50
functions:
  /v1/pets: petstore-function
  /v1/users: user-service-function
metricsInjection: true
metricsName: lambda-response

Usage

To use the LambdaFunctionHandler, add it to your handler.yml chain:

- com.networknt.aws.lambda.LambdaFunctionHandler@lambda

And configure the paths in handler.yml:

paths:
  - path: '/v1/pets'
    method: 'GET'
    handler:
      - lambda