Address review

Author: ptoffy

.github/workflows/pull_request.yml

@@ -36,7 +36,7 @@ jobs:
       # We pass the list of examples here, but we can't pass an array as argument
       # Instead, we pass a String with a valid JSON array.
       # The workaround is mentioned here https://github.com/orgs/community/discussions/11692
-      examples: "[ 'APIGateway', 'APIGateway+LambdaAuthorizer', 'BackgroundTasks', 'HelloJSON', 'HelloWorld', 'ResourcesPackaging', 'S3_AWSSDK', 'S3_Soto', 'Streaming', 'Testing', 'Tutorial' ]"
+      examples: "[ 'APIGateway', 'APIGateway+LambdaAuthorizer', 'BackgroundTasks', 'HelloJSON', 'HelloWorld', 'ResourcesPackaging', 'S3EventNotifier', 'S3_AWSSDK', 'S3_Soto', 'Streaming', 'Testing', 'Tutorial' ]"
       archive_plugin_examples: "[ 'HelloWorld', 'ResourcesPackaging' ]"
       archive_plugin_enabled: true
 

Examples/README.md

@@ -28,6 +28,8 @@ This directory contains example code for Lambda functions.
 
 - **[HelloWorld](HelloWorld/README.md)**: a simple Lambda function (requires [AWS CLI](https://docs.aws.amazon.com/cli/latest/userguide/getting-started-install.html)).
 
+- **[S3EventNotifier](S3EventNotifier/README.md)**: a Lambda function that receives object-upload notifications from an [Amazon S3](https://docs.aws.amazon.com/AmazonS3/latest/userguide/Welcome.html) bucket.
+
 - **[S3_AWSSDK](S3_AWSSDK/README.md)**: a Lambda function that uses the [AWS SDK for Swift](https://docs.aws.amazon.com/sdk-for-swift/latest/developer-guide/getting-started.html) to invoke an [Amazon S3](https://docs.aws.amazon.com/AmazonS3/latest/userguide/Welcome.html) API (requires [AWS SAM](https://aws.amazon.com/serverless/sam/)).
 
 - **[S3_Soto](S3_Soto/README.md)**: a Lambda function that uses [Soto](https://github.com/soto-project/soto) to invoke an [Amazon S3](https://docs.aws.amazon.com/AmazonS3/latest/userguide/Welcome.html) API (requires [AWS SAM](https://aws.amazon.com/serverless/sam/)).
@@ -64,4 +66,4 @@ To obtain these keys, you need an AWS account:
 
 4. **(Optional) Generate Temporary Security Credentials**: If you’re using temporary credentials (which are more secure for short-term access), use AWS Security Token Service (STS). You can call the `GetSessionToken` or `AssumeRole` API to generate temporary credentials, including a session token.
 
-With these in hand, you can use AWS SigV4 to securely sign your requests and interact with AWS services from your Swift app.
+With these in hand, you can use AWS SigV4 to securely sign your requests and interact with AWS services from your Swift app.

Examples/S3EventNotifier/Package.swift

@@ -5,20 +5,18 @@ import PackageDescription
 import struct Foundation.URL
 
 let package = Package(
-    name: "CSVUploadAPINotificationLambda",
+    name: "S3EventNotifier",
     platforms: [.macOS(.v15)],
     dependencies: [
         .package(url: "https://github.com/swift-server/swift-aws-lambda-runtime.git", branch: "main"),
         .package(url: "https://github.com/swift-server/swift-aws-lambda-events", branch: "main"),
-        .package(url: "https://github.com/swift-server/async-http-client.git", from: "1.24.0"),
     ],
     targets: [
         .executableTarget(
-            name: "CSVUploadAPINotificationLambda",
+            name: "S3EventNotifier",
             dependencies: [
                 .product(name: "AWSLambdaRuntime", package: "swift-aws-lambda-runtime"),
                 .product(name: "AWSLambdaEvents", package: "swift-aws-lambda-events"),
-                .product(name: "AsyncHTTPClient", package: "async-http-client"),
             ]
         )
     ]

Examples/S3EventNotifier/README.md

@@ -1,10 +1,10 @@
 # S3 Event Notifier
 
-This example demonstrates how to create a Lambda that notifies an API of an S3 event in a bucket.
+This example demonstrates how to write a Lambda that is invoked by an event originating from Amazon S3, such as a new object being uploaded to a bucket.
 
 ## Code
 
-In this example the lambda function receives an `S3Event` object from the `AWSLambdaEvents` library as input object instead of a `APIGatewayV2Request`. The `S3Event` object contains all the information about the S3 event that triggered the lambda, but what we are interested in is the bucket name and the object key, which are inside of a notification `Record`. The object contains an array of records, however since the lambda is triggered by a single event, we can safely assume that there is only one record in the array: the first one. Inside of this record, we can find the bucket name and the object key:
+In this example the lambda function receives an `S3Event` object defined in the `AWSLambdaEvents` library as input object. The `S3Event` object contains all the information about the S3 event that triggered the function, but what we are interested in is the bucket name and the object key, which are inside of a notification `Record`. The object contains an array of records, however since the lambda is triggered by a single event, we can safely assume that there is only one record in the array: the first one. Inside of this record, we can find the bucket name and the object key:
 
 ```swift
 guard let s3NotificationRecord = event.records.first else {
@@ -17,8 +17,6 @@ let key = s3NotificationRecord.s3.object.key.replacingOccurrences(of: "+", with:
 
 The key is URL encoded, so we replace the `+` with a space.
 
-Once the event is decoded, the lambda sends a POST request to an API endpoint with the bucket name and the object key as parameters. The API URL is set as an environment variable.
-
 ## Build & Package 
 
 To build & archive the package you can use the following commands:
@@ -36,17 +34,46 @@ To deploy the Lambda function, you can use the `aws` command line:
 
 ```bash
 aws lambda create-function \
---function-name S3EventNotifier \
---zip-file fileb://.build/plugins/AWSLambdaPackager/outputs/AWSLambdaPackager/S3EventNotifier/S3EventNotifier.zip \
---runtime provided.al2 \
---handler provided  \
---architectures arm64 \
---role arn:aws:iam::<YOUR_ACCOUNT_ID>:role/lambda_basic_execution
+    --function-name S3EventNotifier \
+    --zip-file fileb://.build/plugins/AWSLambdaPackager/outputs/AWSLambdaPackager/S3EventNotifier/S3EventNotifier.zip \
+    --runtime provided.al2 \
+    --handler provided  \
+    --architectures arm64 \
+    --role arn:aws:iam::<YOUR_ACCOUNT_ID>:role/lambda_basic_execution
 ```
 
 The `--architectures` flag is only required when you build the binary on an Apple Silicon machine (Apple M1 or more recent). It defaults to `x64`.
 
-Be sure to replace <YOUR_ACCOUNT_ID> with your actual AWS account ID (for example: 012345678901).
+Be sure to replace `<YOUR_ACCOUNT_ID>` with your actual AWS account ID (for example: 012345678901).
+
+Besides deploying the lambda function you also need to create the S3 bucket and configure it to send events to the lambda function. You can do this using the following commands:
+
+```bash
+aws s3api create-bucket --bucket my-test-bucket --region eu-west-1 --create-bucket-configuration LocationConstraint=eu-west-1
+
+aws lambda add-permission \
+    --function-name ProcessS3Upload \
+    --statement-id S3InvokeFunction \
+    --action lambda:InvokeFunction \
+    --principal s3.amazonaws.com \
+    --source-arn arn:aws:s3:::my-test-bucket
+
+aws s3api put-bucket-notification-configuration \
+    --bucket my-test-bucket \
+    --notification-configuration '{
+        "LambdaFunctionConfigurations": [{
+            "LambdaFunctionArn": "arn:aws:lambda:<REGION>:<YOUR_ACCOUNT_ID>:function:ProcessS3Upload",
+            "Events": ["s3:ObjectCreated:*"]
+        }]
+    }'
+
+aws s3 cp testfile.txt s3://my-test-bucket/
+```
+
+This will:
+ - create a bucket named `my-test-bucket` in the `eu-west-1` region;
+ - add a permission to the lambda function to be invoked by the bucket;
+ - configure the bucket to send `s3:ObjectCreated:*` events to the lambda function named `ProcessS3Upload`;
+ - upload a file named `testfile.txt` to the bucket.
 
-> [!WARNING]
-> You will have to set up an S3 bucket and configure it to send events to the lambda function. This is not covered in this example.
+Replace `<REGION>` with the region where you deployed the lambda function and `<YOUR_ACCOUNT_ID>` with your actual AWS account ID.

Examples/S3EventNotifier/Sources/main.swift

@@ -2,7 +2,7 @@
 //
 // This source file is part of the SwiftAWSLambdaRuntime open source project
 //
-// Copyright (c) 2024 Apple Inc. and the SwiftAWSLambdaRuntime project authors
+// Copyright (c) 2025 Apple Inc. and the SwiftAWSLambdaRuntime project authors
 // Licensed under Apache License v2.0
 //
 // See LICENSE.txt for license information
@@ -24,63 +24,20 @@ import Foundation
 
 let httpClient = HTTPClient.shared
 
-enum LambdaError: Error {
-    case noNotificationRecord
-    case missingEnvVar(name: String)
+let runtime = LambdaRuntime { (event: S3Event, context: LambdaContext) async throws in
+    context.logger.debug("Received S3 event: \(event)")
 
-    var description: String {
-        switch self {
-        case .noNotificationRecord:
-            "No notification record in S3 event"
-        case .missingEnvVar(let name):
-            "Missing env var named \(name)"
-        }
+    guard let s3NotificationRecord = event.records.first else {
+        context.logger.error("No S3 notification record found in the event")
+        return
     }
-}
-
-let runtime = LambdaRuntime { (event: S3Event, context: LambdaContext) async throws -> APIGatewayV2Response in
-    do {
-        context.logger.debug("Received S3 event: \(event)")
-
-        guard let s3NotificationRecord = event.records.first else {
-            throw LambdaError.noNotificationRecord
-        }
-
-        let bucket = s3NotificationRecord.s3.bucket.name
-        let key = s3NotificationRecord.s3.object.key.replacingOccurrences(of: "+", with: " ")
 
-        guard let apiURL = ProcessInfo.processInfo.environment["API_URL"] else {
-            throw LambdaError.missingEnvVar(name: "API_URL")
-        }
+    let bucket = s3NotificationRecord.s3.bucket.name
+    let key = s3NotificationRecord.s3.object.key.replacingOccurrences(of: "+", with: " ")
 
-        let body = """
-            {
-                "bucket": "\(bucket)",
-                "key": "\(key)"
-            }
-            """
+    context.logger.info("Received notification from S3 bucket '\(bucket)' for object with key '\(key)'")
 
-        context.logger.debug("Sending request to \(apiURL) with body \(body)")
-
-        var request = HTTPClientRequest(url: "\(apiURL)/upload-complete/")
-        request.method = .POST
-        request.headers = [
-            "Content-Type": "application/json"
-        ]
-        request.body = .bytes(.init(string: body))
-
-        let response = try await httpClient.execute(request, timeout: .seconds(30))
-        return APIGatewayV2Response(
-            statusCode: .ok,
-            body: "Lambda terminated successfully. API responded with: Status: \(response.status), Body: \(response.body)"
-        )
-    } catch let error as LambdaError {
-        context.logger.error("\(error.description)")
-        return APIGatewayV2Response(statusCode: .internalServerError, body: "[ERROR] \(error.description)")
-    } catch {
-        context.logger.error("\(error)")
-        return APIGatewayV2Response(statusCode: .internalServerError, body: "[ERROR] \(error)")
-    }
+    // Here you could, for example, notify an API or a messaging service
 }
 
 try await runtime.run()