swift-aws-lambda-runtime/Sources/AWSLambdaRuntime/Docs.docc/quick-setup.md

Getting Started Quickly

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Learn how to create your first project in 3 minutes.

Follow these instructions to get a high-level overview of the steps to write, test, and deploy your first Lambda function written in Swift.

For a detailed step-by-step instruction, follow the tutorial instead.

doc:/tutorials/table-of-content

For the impatient, keep reading.

High-level instructions

Follow these 6 steps to write, test, and deploy a Lambda function in Swift.

1. Create a Swift project for an executable target

swift package init --type executable 

2. Add dependencies on AWSLambdaRuntime library

// swift-tools-version:6.2
// The swift-tools-version declares the minimum version of Swift required to build this package.

import PackageDescription

let package = Package(
    name: "YourProjetName",
    platforms: [
        .macOS(.v15),
    ],
    products: [
        .executable(name: "MyFirstLambdaFunction", targets: ["MyFirstLambdaFunction"]),
    ],
    dependencies: [
        .package(url: "https://github.com/awslabs/swift-aws-lambda-runtime.git", from: "2.0.0"),
    ],
    targets: [
        .executableTarget(
            name: "MyFirstLambdaFunction",
            dependencies: [
                .product(name: "AWSLambdaRuntime", package: "swift-aws-lambda-runtime"),
            ],
            path: "Sources"
        ),
    ]
)

3. Write your function code.

Create an instance of LambdaRuntime and pass a function as a closure. The function has this signature: (_: Event, context: LambdaContext) async throws -> Output (as defined in the LambdaHandler protocol). Event must be Decodable. Output must be Encodable.

If your Lambda function is invoked by another AWS service, use the AWSLambdaEvent library at https://github.com/awslabs/swift-aws-lambda-events to represent the input event.

Finally, call runtime.run() to start the event loop.

// the data structure to represent the input parameter
struct HelloRequest: Decodable {
    let name: String
    let age: Int
}

// the data structure to represent the output response
struct HelloResponse: Encodable {
    let greetings: String
}

// the Lambda runtime
let runtime = LambdaRuntime {
    (event: HelloRequest, context: LambdaContext) in

    HelloResponse(
        greetings: "Hello \(event.name). You look \(event.age > 30 ? "younger" : "older") than your age."
    )
}

// start the loop
try await runtime.run()

4. Test your code locally

swift run  # this starts a local server on port 7000

# Switch to another Terminal tab

curl --header "Content-Type: application/json" \
     --request POST                            \
     --data '{"name": "Seb", "age": 50}'       \
     http://localhost:7000/invoke

{"greetings":"Hello Seb. You look younger than your age."}

5. Build and package your code for AWS Lambda

AWS Lambda runtime runs on Amazon Linux. You must compile your code for Amazon Linux.

Be sure to have Docker installed for this step.

swift package --allow-network-connections docker archive

-------------------------------------------------------------------------
building "MyFirstLambdaFunction" in docker
-------------------------------------------------------------------------
updating "swift:amazonlinux2" docker image
  amazonlinux2: Pulling from library/swift
  Digest: sha256:5b0cbe56e35210fa90365ba3a4db9cd2b284a5b74d959fc1ee56a13e9c35b378
  Status: Image is up to date for swift:amazonlinux2
  docker.io/library/swift:amazonlinux2
building "MyFirstLambdaFunction"
  Building for production...
...
-------------------------------------------------------------------------
archiving "MyFirstLambdaFunction"
-------------------------------------------------------------------------
1 archive created
  * MyFirstLambdaFunction at /Users/YourUserName/MyFirstLambdaFunction/.build/plugins/AWSLambdaPackager/outputs/AWSLambdaPackager/MyFirstLambdaFunction/MyFirstLambdaFunction.zip


cp .build/plugins/AWSLambdaPackager/outputs/AWSLambdaPackager/MyFirstLambdaFunction/MyFirstLambdaFunction.zip ~/Desktop

6. Deploy on AWS Lambda

Be sure to have an AWS Account to follow these steps.

• Connect to the AWS Console
• Navigate to Lambda
• Create a function
• Select Provide your own bootstrap on Amazon Linux 2 as Runtime
• Select an Architecture that matches the one of the machine where you build the code. Select x86_64 when you build on Intel-based Macs or arm64 for Apple Silicon-based Macs.
• Upload the ZIP create during step 5
• Select the Test tab, enter a test event such as {"name": "Seb", "age": 50} and select Test

If the test succeeds, you will see the result: {"greetings":"Hello Seb. You look younger than your age."}.

Congratulations 🎉! You just wrote, test, build, and deployed a Lambda function written in Swift.