Files
Sébastien Stormacq 97b2e6d017 Add support for Lambda functions exposed behind an Application Load Balancer (ALB) (#29)
This PR adds support for exposing Swift OpenAPI Lambda functions behind
an Application Load Balancer (ALB), providing an alternative to API
Gateway for HTTP routing to Lambda functions.

## Changes

### New ALB Support
- **OpenAPILambdaALB Protocol**: New protocol for ALB integration
alongside existing API Gateway support
- **ALB Event Handling**: Added `ALBTargetGroupRequest` and
`ALBTargetGroupResponse` support
- **HTTP Request Conversion**: Extension methods to convert ALB events
to/from HTTP requests/responses

### Core Library Updates
- **ALB-related source files**: New `/Sources/ALB/` directory with
ALB-specific implementations
- **Event Type Support**: Support for `ALBTargetGroupRequest` events
from Elastic Load Balancing
- **Response Mapping**: Proper mapping from OpenAPI responses to ALB
target group responses

### Complete ALB Example
- **QuoteAPI ALB Example**: Full working example in
`Examples/quoteapi-alb/`
- **Infrastructure as Code**: Complete SAM template with VPC, subnets,
security groups, and ALB
- **Build System**: Makefile and Docker build support for ALB deployment
- **Documentation**: Comprehensive README with ALB-specific deployment
instructions

### Key Files Added
```
Sources/ALB/
├── OpenAPILambdaALB.swift
└── ALBTargetGroup+HTTPRequest.swift

Examples/quoteapi-alb/
├── Package.swift
├── template.yaml
├── Makefile
├── README.md
├── Sources/QuoteAPI/QuoteService.swift
├── Sources/QuoteAPI/openapi.yaml
├── Sources/QuoteAPI/openapi-generator-config.yaml
└── events/GetQuote.json
```

## Usage

### Simple ALB Integration
```swift
@main
struct QuoteServiceALBImpl: APIProtocol, OpenAPILambdaALB {
    func register(transport: OpenAPILambdaTransport) throws {
        try self.registerHandlers(on: transport)
    }
    
    static func main() async throws {
        let service = QuoteServiceALBImpl()
        try await service.run()
    }
    
    // Your OpenAPI implementation...
}
```

### Key Differences from API Gateway
- Uses `OpenAPILambdaALB` instead of `OpenAPILambdaHttpApi`
- Handles `ALBTargetGroupRequest` events instead of
`APIGatewayV2Request`
- Returns `ALBTargetGroupResponse` instead of `APIGatewayV2Response`
- Requires VPC infrastructure (included in SAM template)
- No built-in authorization (implement via custom middleware if needed)

## Benefits

- **Cost Optimization**: ALB can be more cost-effective for high-traffic
applications
- **VPC Integration**: Native VPC support for private network access
- **Load Balancing**: Advanced load balancing features and health checks
- **WebSocket Support**: Future WebSocket support through ALB
- **Flexibility**: Choice between API Gateway and ALB based on use case

## Testing

-  ALB example builds successfully with `sam build`
-  Local testing with `sam local invoke`
-  Complete infrastructure deployment via SAM
-  HTTP requests properly routed through ALB to Lambda
-  OpenAPI specification compatibility maintained

## Deployment

Deploy the ALB example:
```bash
cd Examples/quoteapi-alb
sam build && sam deploy --guided
```

Test the deployed endpoint:
```bash
curl http://[alb-dns-name]/stocks/AAPL
```

## Backward Compatibility

This is a purely additive change:
- Existing API Gateway implementations continue to work unchanged
- No breaking changes to existing APIs
- New ALB support is opt-in via protocol conformance
2025-10-26 09:10:09 +01:00

80 lines
2.5 KiB
Swift

//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift OpenAPI Lambda open source project
//
// Copyright Swift OpenAPI Lambda project authors
// Copyright (c) 2025 Amazon.com, Inc. or its affiliates.
// Licensed under Apache License v2.0
//
// See LICENSE.txt for license information
// See CONTRIBUTORS.txt for the list of Swift OpenAPI Lambda project authors
//
// SPDX-License-Identifier: Apache-2.0
//
//===----------------------------------------------------------------------===//
import Foundation
import Logging
import OpenAPIRuntime
import OpenAPILambda
@main
struct QuoteServiceALBImpl: APIProtocol, OpenAPILambdaALB {
let logger: Logger
func register(transport: OpenAPILambdaTransport) throws {
// OPTIONAL
// you have a chance here to customize the routes, for example
try transport.router.get("/health") { _, _ in
"OK"
}
logger.trace("Available Routes\n\(transport.router)") // print the router tree (for debugging purposes)
// OPTIONAL
// to log all requests and their responses, add a logging middleware
let loggingMiddleware = LoggingMiddleware(logger: logger)
// MANDATORY (middlewares are optional)
try self.registerHandlers(on: transport, middlewares: [loggingMiddleware])
}
static func main() async throws {
let openAPIService = QuoteServiceALBImpl()
try await openAPIService.run()
}
init() {
var logger = Logger(label: "QuoteServiceALB")
logger.logLevel = .trace
self.logger = logger
}
func getQuote(_ input: Operations.getQuote.Input) async throws -> Operations.getQuote.Output {
logger.trace("GetQuote - Started")
let symbol = input.path.symbol
var date: Date = Date()
if let dateString = input.query.date {
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyyMMdd"
date = dateFormatter.date(from: dateString) ?? Date()
}
let price = Components.Schemas.quote(
symbol: symbol,
price: Double.random(in: 100..<150).rounded(),
change: Double.random(in: -5..<5).rounded(),
changePercent: Double.random(in: -0.05..<0.05),
volume: Double.random(in: 10000..<100000).rounded(),
timestamp: date
)
logger.trace("GetQuote - Returning")
return .ok(.init(body: .json(price)))
}
}