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Sébastien Stormacq
97583a78c2
This PR adds a new example demonstrating how to build a Lambda function that handles requests from multiple sources (Application Load Balancer and API Gateway V2) using a single handler. ### What's New **New Example: `Examples/MultiSourceAPI`** A Lambda function that: - Implements `StreamingLambdaHandler` to accept raw `ByteBuffer` events - Dynamically decodes events as either `ALBTargetGroupRequest` or `APIGatewayV2Request` - Returns appropriate responses based on the detected event source - Demonstrates handling multiple AWS service integrations with a single function ### Key Features - **Type-safe event detection**: Uses Swift's `Decodable` to identify the event source at runtime - **Streaming response**: Implements `StreamingLambdaHandler` for efficient response handling - **Complete deployment**: Includes SAM template with both ALB and API Gateway V2 infrastructure - **Production-ready**: Full VPC setup with subnets, security groups, and load balancer configuration ### Files Added - `Examples/MultiSourceAPI/Sources/main.swift` - Lambda handler implementation - `Examples/MultiSourceAPI/Package.swift` - Swift package configuration - `Examples/MultiSourceAPI/template.yaml` - SAM deployment template with ALB and API Gateway V2 - `Examples/MultiSourceAPI/README.md` - Documentation with build, deploy, and test instructions - Updated CI to include the new example ### Use Case This pattern is useful when you want to: - Expose the same Lambda function through multiple AWS services - Reduce code duplication by handling similar requests from different sources - Maintain a single codebase for multi-channel APIs --------- Co-authored-by: Sebastien Stormacq <stormacq@amazon.lu> Co-authored-by: Josh Elkins <jbelkins@users.noreply.github.com>
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Multi-Source API Example
This example demonstrates a Lambda function that handles requests from both Application Load Balancer (ALB) and API Gateway V2 by accepting a raw ByteBuffer and decoding the appropriate event type.
Overview
The Lambda handler receives events as ByteBuffer and attempts to decode them as either:
ALBTargetGroupRequest- for requests from Application Load BalancerAPIGatewayV2Request- for requests from API Gateway V2
Based on the successfully decoded type, it returns an appropriate response.
Building
swift package archive --allow-network-connections docker
Deploying
Deploy using SAM:
sam deploy \
--resolve-s3 \
--template-file template.yaml \
--stack-name MultiSourceAPI \
--capabilities CAPABILITY_IAM
Testing
After deployment, SAM will output two URLs:
Test API Gateway V2:
curl https://<api-id>.execute-api.<region>.amazonaws.com/apigw/test
Expected response:
{"source":"APIGatewayV2","path":"/apigw/test"}
Test ALB:
curl http://<alb-dns-name>/alb/test
Expected response:
{"source":"ALB","path":"/alb/test"}
How It Works
The handler uses Swift's type-safe decoding to determine the event source:
- Receives raw
ByteBufferevent - Attempts to decode as
ALBTargetGroupRequest - If that fails, attempts to decode as
APIGatewayV2Request - Returns appropriate response based on the decoded type
- Throws error if neither decoding succeeds
This pattern is useful when a single Lambda function needs to handle requests from multiple sources.