From 81eeab351f3a81d0244e9884de0b5c9c049a1dc8 Mon Sep 17 00:00:00 2001 From: tom doron Date: Mon, 9 Jan 2023 13:54:19 -0800 Subject: [PATCH 1/7] udpate readme to reflect 1.x API motivation: prepare documentation in preperation for 1.x release changes: update readme with 1.x API --- readme.md | 611 +++++++++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 539 insertions(+), 72 deletions(-) diff --git a/readme.md b/readme.md index 8ffcff85..e1972e07 100644 --- a/readme.md +++ b/readme.md @@ -14,6 +14,543 @@ Swift AWS Lambda Runtime was designed to make building Lambda functions in Swift If you have never used AWS Lambda or Docker before, check out this [getting started guide](https://fabianfett.de/getting-started-with-swift-aws-lambda-runtime) which helps you with every step from zero to a running Lambda. +First, create a SwiftPM project and pull Swift AWS Lambda Runtime as dependency into your project + + ```swift + // swift-tools-version:5.7 + + import PackageDescription + + let package = Package( + name: "MyLambda", + products: [ + .executable(name: "MyLambda", targets: ["MyLambda"]), + ], + dependencies: [ + .package(url: "https://github.com/swift-server/swift-aws-lambda-runtime.git", from: "1.0.0-alpha"), + ], + targets: [ + .executableTarget(name: "MyLambda", dependencies: [ + .product(name: "AWSLambdaRuntime", package: "swift-aws-lambda-runtime"), + ]), + ] + ) + ``` + +Next, create a `MyLambda.swift` and implement your Lambda. + +### Using async function + + The simplest way to use `AWSLambdaRuntime` is to use the `SimpleLambdaHandler` protocol and pass in a async function, for example: + + ```swift + // Import the module + import AWSLambdaRuntime + + @main + struct MyLambda: SimpleLambdaHandler { + // in this example we are receiving and responding with strings + func handle(_ name: String, context: LambdaContext) async throws -> String { + return "Hello, \(name)" + } + } + ``` + + More commonly, the event would be a JSON, which is modeled using `Codable`, for example: + + ```swift + // Import the module + import AWSLambdaRuntime + + // Request, uses Codable for transparent JSON encoding + struct Request: Codable { + let name: String + } + + // Response, uses Codable for transparent JSON encoding + struct Response: Codable { + let message: String + } + + @main + struct MyLambda: SimpleLambdaHandler { + // In this example we are receiving and responding with `Codable`. + func handle(_ request: Request, context: LambdaContext) async throws -> Response { + Response(message: "Hello, \(request.name)") + } + } + ``` + + Since most Lambda functions are triggered by events originating in the AWS platform like `SNS`, `SQS` or `APIGateway`, the [Swift AWS Lambda Events](http://github.com/swift-server/swift-aws-lambda-events) package includes an `AWSLambdaEvents` module that provides implementations for most common AWS event types further simplifying writing Lambda functions. For example, handling an `SQS` message: + + First, add a dependency on the event packages: + + ```swift + // swift-tools-version:5.7 + + import PackageDescription + + let package = Package( + name: "MyLambda", + products: [ + .executable(name: "MyLambda", targets: ["MyLambda"]), + ], + dependencies: [ + .package(url: "https://github.com/swift-server/swift-aws-lambda-runtime.git", from: "1.0.0-alpha"), + .package(url: "https://github.com/swift-server/swift-aws-lambda-events.git", branch: "main"), + ], + targets: [ + .executableTarget(name: "MyLambda", dependencies: [ + .product(name: "AWSLambdaRuntime", package: "swift-aws-lambda-runtime"), + .product(name: "AWSLambdaEvents", package: "swift-aws-lambda-events"), + ]), + ] + ) + ``` + + Then in your Lambda: + + ```swift + // Import the modules + import AWSLambdaRuntime + import AWSLambdaEvents + + // In this example we are receiving an SQS Event, with no response (Void). + @main + struct MyLambda: SimpleLambdaHandler { + // In this example we are receiving and responding with `Codable`. + func handle(_ event: SQS.Event, context: LambdaContext) async throws -> Void { + ... + } + } + ``` + + In some cases, the Lambda needs to do work on initialization. + In such cases, use the `LambdaHandler` instead of the `SimpleLambdaHandler` which has an additional initialization method. For example: + + ```swift + import AWSLambdaRuntime + + @main + struct MyLambda: LambdaHandler { + init(context: LambdaInitializationContext) async throws { + ... + } + + func handle(_ event: String, context: LambdaContext) async throws -> Void { + ... + } + } + ``` + + Modeling Lambda functions as async functions is both simple and safe. Swift AWS Lambda Runtime will ensure that the user-provided code is offloaded from the network processing thread such that even if the code becomes slow to respond or gets hang, the underlying process can continue to function. This safety comes at a small performance penalty from context switching between threads. In many cases, the simplicity and safety of using the Closure based API is often preferred over the complexity of the performance-oriented API. + +### Using EventLoopLambdaHandler + + Performance sensitive Lambda functions may choose to use a more complex API which allows user code to run on the same thread as the networking handlers. Swift AWS Lambda Runtime uses [SwiftNIO](https://github.com/apple/swift-nio) as its underlying networking engine which means the APIs are based on [SwiftNIO](https://github.com/apple/swift-nio) concurrency primitives like the `EventLoop` and `EventLoopFuture`. For example: + + ```swift + // Import the modules + import AWSLambdaRuntime + import AWSLambdaEvents + import NIOCore + + @main + struct Handler: EventLoopLambdaHandler { + typealias Event = SNSEvent.Message // Event / Request type + typealias Output = Void // Output / Response type + + static func makeHandler(context: LambdaInitializationContext) -> EventLoopFuture { + context.eventLoop.makeSucceededFuture(Self()) + } + + // `EventLoopLambdaHandler` does not offload the Lambda processing to a separate thread + // while the closure-based handlers do. + func handle(_ event: Event, context: LambdaContext) -> EventLoopFuture { + ... + context.eventLoop.makeSucceededFuture(Void()) + } + } + ``` + + Beyond the small cognitive complexity of using the `EventLoopFuture` based APIs, note these APIs should be used with extra care. An `EventLoopLambdaHandler` will execute the user code on the same `EventLoop` (thread) as the library, making processing faster but requiring the user code to never call blocking APIs as it might prevent the underlying process from functioning. + +## Deploying to AWS Lambda + +To deploy Lambda functions to AWS Lambda, you need to compile the code for Amazon Linux which is the OS used on AWS Lambda microVMs, package it as a Zip file, and upload to AWS. + +Swift AWS Lambda Runtime includes a SwiftPM plugin designed to help with the creation of of the zip archive. +To build and package your Lambda, run the following command: + + ```shell + swift package archive + ``` + + on macOS, the archiving plugin uses docker to build the Lambda for Amazon Linux 2, and as such requires to communicate with Docker over the localhost network. + At the moment, SwiftPM does not allow plugin communication over network, and as such the invocation requires breaking from the SwiftPM plugin sandbox. This limitation would be removed in the future. + +```shell + swift package --disable-sandbox archive + ``` + +AWS offers several tools to interact and deploy Lambda functions to AWS Lambda including [SAM](https://aws.amazon.com/serverless/sam/) and the [AWS CLI](https://aws.amazon.com/cli/). The [Examples Directory](/Examples) includes complete sample build and deployment scripts that utilize these tools. + +Note the examples mentioned above use dynamic linking, therefore bundle the required Swift libraries in the Zip package along side the executable. You may choose to link the Lambda function statically (using `-static-stdlib`) which could improve performance but requires additional linker flags. + +To build the Lambda function for Amazon Linux 2, use the Docker image published by Swift.org on [Swift toolchains and Docker images for Amazon Linux 2](https://swift.org/download/), as demonstrated in the examples. + +## Architecture + +The library defines four protocols for the implementation of a Lambda Handler. From low-level to more convenient: + +### ByteBufferLambdaHandler + +An `EventLoopFuture` based processing protocol for a Lambda that takes a `ByteBuffer` and returns a `ByteBuffer?` asynchronously. + +`ByteBufferLambdaHandler` is the lowest level protocol designed to power the higher level `EventLoopLambdaHandler` and `LambdaHandler` based APIs. Users are not expected to use this protocol, though some performance sensitive applications that operate at the `ByteBuffer` level or have special serialization needs may choose to do so. + +```swift +public protocol ByteBufferLambdaHandler { + /// Create a Lambda handler for the runtime. + /// + /// Use this to initialize all your resources that you want to cache between invocations. This could be database + /// connections and HTTP clients for example. It is encouraged to use the given `EventLoop`'s conformance + /// to `EventLoopGroup` when initializing NIO dependencies. This will improve overall performance, as it + /// minimizes thread hopping. + static func makeHandler(context: LambdaInitializationContext) -> EventLoopFuture + + /// The Lambda handling method. + /// Concrete Lambda handlers implement this method to provide the Lambda functionality. + /// + /// - parameters: + /// - context: Runtime ``LambdaContext``. + /// - event: The event or input payload encoded as `ByteBuffer`. + /// + /// - Returns: An `EventLoopFuture` to report the result of the Lambda back to the runtime engine. + /// The `EventLoopFuture` should be completed with either a response encoded as `ByteBuffer` or an `Error`. + func handle(_ buffer: ByteBuffer, context: LambdaContext) -> EventLoopFuture +} +``` + +### EventLoopLambdaHandler + +`EventLoopLambdaHandler` is a strongly typed, `EventLoopFuture` based asynchronous processing protocol for a Lambda that takes a user defined `Event` and returns a user defined `Output`. + +`EventLoopLambdaHandler` provides `ByteBuffer` -> `Event` decoding and `Output` -> `ByteBuffer?` encoding for `Codable` and `String`. + +`EventLoopLambdaHandler` executes the user provided Lambda on the same `EventLoop` as the core runtime engine, making the processing fast but requires more care from the implementation to never block the `EventLoop`. It it designed for performance sensitive applications that use `Codable` or `String` based Lambda functions. + +```swift +public protocol EventLoopLambdaHandler { + /// The lambda functions input. In most cases this should be `Codable`. If your event originates from an + /// AWS service, have a look at [AWSLambdaEvents](https://github.com/swift-server/swift-aws-lambda-events), + /// which provides a number of commonly used AWS Event implementations. + associatedtype Event + /// The lambda functions output. Can be `Void`. + associatedtype Output + + /// Create a Lambda handler for the runtime. + /// + /// Use this to initialize all your resources that you want to cache between invocations. This could be database + /// connections and HTTP clients for example. It is encouraged to use the given `EventLoop`'s conformance + /// to `EventLoopGroup` when initializing NIO dependencies. This will improve overall performance, as it + /// minimizes thread hopping. + static func makeHandler(context: LambdaInitializationContext) -> EventLoopFuture + + /// The Lambda handling method. + /// Concrete Lambda handlers implement this method to provide the Lambda functionality. + /// + /// - parameters: + /// - context: Runtime ``LambdaContext``. + /// - event: Event of type `Event` representing the event or request. + /// + /// - Returns: An `EventLoopFuture` to report the result of the Lambda back to the runtime engine. + /// The `EventLoopFuture` should be completed with either a response of type ``Output`` or an `Error`. + func handle(_ event: Event, context: LambdaContext) -> EventLoopFuture + + /// Encode a response of type ``Output`` to `ByteBuffer`. + /// Concrete Lambda handlers implement this method to provide coding functionality. + /// - parameters: + /// - value: Response of type ``Output``. + /// - buffer: A `ByteBuffer` to encode into, will be overwritten. + /// + /// - Returns: A `ByteBuffer` with the encoded version of the `value`. + func encode(value: Output, into buffer: inout ByteBuffer) throws + + /// Decode a `ByteBuffer` to a request or event of type ``Event``. + /// Concrete Lambda handlers implement this method to provide coding functionality. + /// + /// - parameters: + /// - buffer: The `ByteBuffer` to decode. + /// + /// - Returns: A request or event of type ``Event``. + func decode(buffer: ByteBuffer) throws -> Event +} +``` + +### LambdaHandler + +`LambdaHandler` is a strongly typed, completion handler based asynchronous processing protocol for a Lambda that takes a user defined `Event` and returns a user defined `Output`. + +`LambdaHandler` provides `ByteBuffer` -> `Event` decoding and `Output` -> `ByteBuffer` encoding for `Codable` and `String`. + +`LambdaHandler` offloads the user provided Lambda execution to an async task making processing safer but slightly slower. + +```swift +public protocol LambdaHandler { + /// The lambda function's input. In most cases this should be `Codable`. If your event originates from an + /// AWS service, have a look at [AWSLambdaEvents](https://github.com/swift-server/swift-aws-lambda-events), + /// which provides a number of commonly used AWS Event implementations. + associatedtype Event + /// The lambda function's output. Can be `Void`. + associatedtype Output + + /// The Lambda initialization method. + /// Use this method to initialize resources that will be used in every request. + /// + /// Examples for this can be HTTP or database clients. + /// - parameters: + /// - context: Runtime ``LambdaInitializationContext``. + init(context: LambdaInitializationContext) async throws + + /// The Lambda handling method. + /// Concrete Lambda handlers implement this method to provide the Lambda functionality. + /// + /// - parameters: + /// - event: Event of type `Event` representing the event or request. + /// - context: Runtime ``LambdaContext``. + /// + /// - Returns: A Lambda result ot type `Output`. + func handle(_ event: Event, context: LambdaContext) async throws -> Output + + /// Encode a response of type ``Output`` to `ByteBuffer`. + /// Concrete Lambda handlers implement this method to provide coding functionality. + /// - parameters: + /// - value: Response of type ``Output``. + /// - buffer: A `ByteBuffer` to encode into, will be overwritten. + /// + /// - Returns: A `ByteBuffer` with the encoded version of the `value`. + func encode(value: Output, into buffer: inout ByteBuffer) throws + + /// Decode a `ByteBuffer` to a request or event of type ``Event``. + /// Concrete Lambda handlers implement this method to provide coding functionality. + /// + /// - parameters: + /// - buffer: The `ByteBuffer` to decode. + /// + /// - Returns: A request or event of type ``Event``. + func decode(buffer: ByteBuffer) throws -> Event +} +``` + +### SimpleLambdaHandler + +`SimpleLambdaHandler` is a strongly typed, completion handler based asynchronous processing protocol for a Lambda that takes a user defined `Event` and returns a user defined `Output`. + +`SimpleLambdaHandler` provides `ByteBuffer` -> `Event` decoding and `Output` -> `ByteBuffer` encoding for `Codable` and `String`. + +`SimpleLambdaHandler` is the same as `LambdaHandler`, but does not require explicit initialization . + +```swift +public protocol SimpleLambdaHandler { + /// The lambda function's input. In most cases this should be `Codable`. If your event originates from an + /// AWS service, have a look at [AWSLambdaEvents](https://github.com/swift-server/swift-aws-lambda-events), + /// which provides a number of commonly used AWS Event implementations. + associatedtype Event + /// The lambda function's output. Can be `Void`. + associatedtype Output + + init() + + /// The Lambda handling method. + /// Concrete Lambda handlers implement this method to provide the Lambda functionality. + /// + /// - parameters: + /// - event: Event of type `Event` representing the event or request. + /// - context: Runtime ``LambdaContext``. + /// + /// - Returns: A Lambda result ot type `Output`. + func handle(_ event: Event, context: LambdaContext) async throws -> Output + + /// Encode a response of type ``Output`` to `ByteBuffer`. + /// Concrete Lambda handlers implement this method to provide coding functionality. + /// - parameters: + /// - value: Response of type ``Output``. + /// - buffer: A `ByteBuffer` to encode into, will be overwritten. + /// + /// - Returns: A `ByteBuffer` with the encoded version of the `value`. + func encode(value: Output, into buffer: inout ByteBuffer) throws + + /// Decode a `ByteBuffer` to a request or event of type ``Event``. + /// Concrete Lambda handlers implement this method to provide coding functionality. + /// + /// - parameters: + /// - buffer: The `ByteBuffer` to decode. + /// + /// - Returns: A request or event of type ``Event``. + func decode(buffer: ByteBuffer) throws -> Event +} +``` + +### Context + +When calling the user provided Lambda function, the library provides a `LambdaContext` class that provides metadata about the execution context, as well as utilities for logging and allocating buffers. + +```swift +public struct LambdaContext: CustomDebugStringConvertible, Sendable { + /// The request ID, which identifies the request that triggered the function invocation. + public var requestID: String { + self.storage.requestID + } + + /// The AWS X-Ray tracing header. + public var traceID: String { + self.storage.traceID + } + + /// The ARN of the Lambda function, version, or alias that's specified in the invocation. + public var invokedFunctionARN: String { + self.storage.invokedFunctionARN + } + + /// The timestamp that the function times out. + public var deadline: DispatchWallTime { + self.storage.deadline + } + + /// For invocations from the AWS Mobile SDK, data about the Amazon Cognito identity provider. + public var cognitoIdentity: String? { + self.storage.cognitoIdentity + } + + /// For invocations from the AWS Mobile SDK, data about the client application and device. + public var clientContext: String? { + self.storage.clientContext + } + + /// `Logger` to log with. + /// + /// - note: The `LogLevel` can be configured using the `LOG_LEVEL` environment variable. + public var logger: Logger { + self.storage.logger + } + + /// The `EventLoop` the Lambda is executed on. Use this to schedule work with. + /// This is useful when implementing the ``EventLoopLambdaHandler`` protocol. + /// + /// - note: The `EventLoop` is shared with the Lambda runtime engine and should be handled with extra care. + /// Most importantly the `EventLoop` must never be blocked. + public var eventLoop: EventLoop { + self.storage.eventLoop + } + + /// `ByteBufferAllocator` to allocate `ByteBuffer`. + /// This is useful when implementing ``EventLoopLambdaHandler``. + public var allocator: ByteBufferAllocator { + self.storage.allocator + } +} +``` + +Similarally, the library provides a context if and when initializing the Lambda. + +```swift +public struct LambdaInitializationContext: Sendable { + /// `Logger` to log with. + /// + /// - note: The `LogLevel` can be configured using the `LOG_LEVEL` environment variable. + public let logger: Logger + + /// The `EventLoop` the Lambda is executed on. Use this to schedule work with. + /// + /// - note: The `EventLoop` is shared with the Lambda runtime engine and should be handled with extra care. + /// Most importantly the `EventLoop` must never be blocked. + public let eventLoop: EventLoop + + /// `ByteBufferAllocator` to allocate `ByteBuffer`. + public let allocator: ByteBufferAllocator + + /// ``LambdaTerminator`` to register shutdown operations. + public let terminator: LambdaTerminator +} +``` + +### Configuration + +The library’s behavior can be fine tuned using environment variables based configuration. The library supported the following environment variables: + +* `LOG_LEVEL`: Define the logging level as defined by [SwiftLog](https://github.com/apple/swift-log). Set to INFO by default. +* `MAX_REQUESTS`: Max cycles the library should handle before exiting. Set to none by default. +* `STOP_SIGNAL`: Signal to capture for termination. Set to `TERM` by default. +* `REQUEST_TIMEOUT`: Max time to wait for responses to come back from the AWS Runtime engine. Set to none by default. + +### AWS Lambda Runtime Engine Integration + +The library is designed to integrate with AWS Lambda Runtime Engine via the [AWS Lambda Runtime API](https://docs.aws.amazon.com/lambda/latest/dg/runtimes-custom.html) which was introduced as part of [AWS Lambda Custom Runtimes](https://aws.amazon.com/about-aws/whats-new/2018/11/aws-lambda-now-supports-custom-runtimes-and-layers/) in 2018. The latter is an HTTP server that exposes three main RESTful endpoint: + +* `/runtime/invocation/next` +* `/runtime/invocation/response` +* `/runtime/invocation/error` + +A single Lambda execution workflow is made of the following steps: + +1. The library calls AWS Lambda Runtime Engine `/next` endpoint to retrieve the next invocation request. +2. The library parses the response HTTP headers and populate the `Context` object. +3. The library reads the `/next` response body and attempt to decode it. Typically it decodes to user provided `Event` type which extends `Decodable`, but users may choose to write Lambda functions that receive the input as `String` or `ByteBuffer` which require less, or no decoding. +4. The library hands off the `Context` and `Event` event to the user provided handler. In the case of `LambdaHandler` based handler this is done on a dedicated `DispatchQueue`, providing isolation between user's and the library's code. +5. User provided handler processes the request asynchronously, invoking a callback or returning a future upon completion, which returns a `Result` type with the `Output` or `Error` populated. +6. In case of error, the library posts to AWS Lambda Runtime Engine `/error` endpoint to provide the error details, which will show up on AWS Lambda logs. +7. In case of success, the library will attempt to encode the response. Typically it encodes from user provided `Output` type which extends `Encodable`, but users may choose to write Lambda functions that return a `String` or `ByteBuffer`, which require less, or no encoding. The library then posts the response to AWS Lambda Runtime Engine `/response` endpoint to provide the response to the callee. + +The library encapsulates the workflow via the internal `LambdaRuntimeClient` and `LambdaRunner` structs respectively. + +### Lifecycle Management + +AWS Lambda Runtime Engine controls the Application lifecycle and in the happy case never terminates the application, only suspends its execution when no work is available. + +As such, the library's main entry point is designed to run forever in a blocking fashion, performing the workflow described above in an endless loop. + +That loop is broken if/when an internal error occurs, such as a failure to communicate with AWS Lambda Runtime Engine API, or under other unexpected conditions. + +By default, the library also registers a Signal handler that traps `INT` and `TERM`, which are typical Signals used in modern deployment platforms to communicate shutdown request. + +### Integration with AWS Platform Events + +AWS Lambda functions can be invoked directly from the AWS Lambda console UI, AWS Lambda API, AWS SDKs, AWS CLI, and AWS toolkits. More commonly, they are invoked as a reaction to an events coming from the AWS platform. To make it easier to integrate with AWS platform events, [Swift AWS Lambda Runtime Events](http://github.com/swift-server/swift-aws-lambda-events) library is available, designed to work together with this runtime library. [Swift AWS Lambda Runtime Events](http://github.com/swift-server/swift-aws-lambda-events) includes an `AWSLambdaEvents` target which provides abstractions for many commonly used events. + +## Performance + +Lambda functions performance is usually measured across two axes: + +- **Cold start times**: The time it takes for a Lambda function to startup, ask for an invocation and process the first invocation. + +- **Warm invocation times**: The time it takes for a Lambda function to process an invocation after the Lambda has been invoked at least once. + +Larger packages size (Zip file uploaded to AWS Lambda) negatively impact the cold start time, since AWS needs to download and unpack the package before starting the process. + +Swift provides great Unicode support via [ICU](http://site.icu-project.org/home). Therefore, Swift-based Lambda functions include the ICU libraries which tend to be large. This impacts the download time mentioned above and an area for further optimization. Some of the alternatives worth exploring are using the system ICU that comes with Amazon Linux (albeit older than the one Swift ships with) or working to remove the ICU dependency altogether. We welcome ideas and contributions to this end. + +## Security + +Please see [SECURITY.md](SECURITY.md) for details on the security process. + +## Project status + +This is a community-driven open-source project actively seeking contributions. +There are several areas which need additional attention, including but not limited to: + +* Further performance tuning +* Additional documentation and best practices +* Additional examples + +--- +# Version 0.x (previous version) documentation +--- + +## Getting started + +If you have never used AWS Lambda or Docker before, check out this [getting started guide](https://fabianfett.de/getting-started-with-swift-aws-lambda-runtime) which helps you with every step from zero to a running Lambda. + First, create a SwiftPM project and pull Swift AWS Lambda Runtime as dependency into your project ```swift @@ -39,9 +576,9 @@ First, create a SwiftPM project and pull Swift AWS Lambda Runtime as dependency Next, create a `main.swift` and implement your Lambda. - ### Using Closures +### Using Closures - The simplest way to use `AWSLambdaRuntime` is to pass in a closure, for example: +The simplest way to use `AWSLambdaRuntime` is to pass in a closure, for example: ```swift // Import the module @@ -304,73 +841,3 @@ public final class Context { public let allocator: ByteBufferAllocator } ``` - -### Configuration - -The library’s behavior can be fine tuned using environment variables based configuration. The library supported the following environment variables: - -* `LOG_LEVEL`: Define the logging level as defined by [SwiftLog](https://github.com/apple/swift-log). Set to INFO by default. -* `MAX_REQUESTS`: Max cycles the library should handle before exiting. Set to none by default. -* `STOP_SIGNAL`: Signal to capture for termination. Set to `TERM` by default. -* `REQUEST_TIMEOUT`: Max time to wait for responses to come back from the AWS Runtime engine. Set to none by default. - - -### AWS Lambda Runtime Engine Integration - -The library is designed to integrate with AWS Lambda Runtime Engine via the [AWS Lambda Runtime API](https://docs.aws.amazon.com/lambda/latest/dg/runtimes-custom.html) which was introduced as part of [AWS Lambda Custom Runtimes](https://aws.amazon.com/about-aws/whats-new/2018/11/aws-lambda-now-supports-custom-runtimes-and-layers/) in 2018. The latter is an HTTP server that exposes three main RESTful endpoint: - -* `/runtime/invocation/next` -* `/runtime/invocation/response` -* `/runtime/invocation/error` - -A single Lambda execution workflow is made of the following steps: - -1. The library calls AWS Lambda Runtime Engine `/next` endpoint to retrieve the next invocation request. -2. The library parses the response HTTP headers and populate the `Context` object. -3. The library reads the `/next` response body and attempt to decode it. Typically it decodes to user provided `In` type which extends `Decodable`, but users may choose to write Lambda functions that receive the input as `String` or `ByteBuffer` which require less, or no decoding. -4. The library hands off the `Context` and `In` event to the user provided handler. In the case of `LambdaHandler` based handler this is done on a dedicated `DispatchQueue`, providing isolation between user's and the library's code. -5. User provided handler processes the request asynchronously, invoking a callback or returning a future upon completion, which returns a `Result` type with the `Out` or `Error` populated. -6. In case of error, the library posts to AWS Lambda Runtime Engine `/error` endpoint to provide the error details, which will show up on AWS Lambda logs. -7. In case of success, the library will attempt to encode the response. Typically it encodes from user provided `Out` type which extends `Encodable`, but users may choose to write Lambda functions that return a `String` or `ByteBuffer`, which require less, or no encoding. The library then posts the response to AWS Lambda Runtime Engine `/response` endpoint to provide the response to the callee. - -The library encapsulates the workflow via the internal `LambdaRuntimeClient` and `LambdaRunner` structs respectively. - -### Lifecycle Management - -AWS Lambda Runtime Engine controls the Application lifecycle and in the happy case never terminates the application, only suspends its execution when no work is available. - -As such, the library's main entry point is designed to run forever in a blocking fashion, performing the workflow described above in an endless loop. - -That loop is broken if/when an internal error occurs, such as a failure to communicate with AWS Lambda Runtime Engine API, or under other unexpected conditions. - -By default, the library also registers a Signal handler that traps `INT` and `TERM`, which are typical Signals used in modern deployment platforms to communicate shutdown request. - -### Integration with AWS Platform Events - -AWS Lambda functions can be invoked directly from the AWS Lambda console UI, AWS Lambda API, AWS SDKs, AWS CLI, and AWS toolkits. More commonly, they are invoked as a reaction to an events coming from the AWS platform. To make it easier to integrate with AWS platform events, [Swift AWS Lambda Runtime Events](http://github.com/swift-server/swift-aws-lambda-events) library is available, designed to work together with this runtime library. [Swift AWS Lambda Runtime Events](http://github.com/swift-server/swift-aws-lambda-events) includes an `AWSLambdaEvents` target which provides abstractions for many commonly used events. - -## Performance - -Lambda functions performance is usually measured across two axes: - -- **Cold start times**: The time it takes for a Lambda function to startup, ask for an invocation and process the first invocation. - -- **Warm invocation times**: The time it takes for a Lambda function to process an invocation after the Lambda has been invoked at least once. - -Larger packages size (Zip file uploaded to AWS Lambda) negatively impact the cold start time, since AWS needs to download and unpack the package before starting the process. - -Swift provides great Unicode support via [ICU](http://site.icu-project.org/home). Therefore, Swift-based Lambda functions include the ICU libraries which tend to be large. This impacts the download time mentioned above and an area for further optimization. Some of the alternatives worth exploring are using the system ICU that comes with Amazon Linux (albeit older than the one Swift ships with) or working to remove the ICU dependency altogether. We welcome ideas and contributions to this end. - -## Security - -Please see [SECURITY.md](SECURITY.md) for details on the security process. - -## Project status - -This is a community-driven open-source project actively seeking contributions. -While the core API is considered stable, the API may still evolve as we get closer to a `1.0` version. -There are several areas which need additional attention, including but not limited to: - -* Further performance tuning -* Additional documentation and best practices -* Additional examples From 19ab25c1f8df64afe3ebc6b18bf001b47189e50f Mon Sep 17 00:00:00 2001 From: tomer doron Date: Tue, 10 Jan 2023 09:21:11 -0800 Subject: [PATCH 2/7] Update readme.md Co-authored-by: Yim Lee --- readme.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/readme.md b/readme.md index e1972e07..0975d66e 100644 --- a/readme.md +++ b/readme.md @@ -41,7 +41,7 @@ Next, create a `MyLambda.swift` and implement your Lambda. ### Using async function - The simplest way to use `AWSLambdaRuntime` is to use the `SimpleLambdaHandler` protocol and pass in a async function, for example: + The simplest way to use `AWSLambdaRuntime` is to use the `SimpleLambdaHandler` protocol and pass in an async function, for example: ```swift // Import the module From a475976a88a9ba8b5668faa1e69169bd51ab590b Mon Sep 17 00:00:00 2001 From: tomer doron Date: Tue, 10 Jan 2023 09:21:17 -0800 Subject: [PATCH 3/7] Update readme.md Co-authored-by: Yim Lee --- readme.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/readme.md b/readme.md index 0975d66e..41fe112f 100644 --- a/readme.md +++ b/readme.md @@ -51,7 +51,7 @@ Next, create a `MyLambda.swift` and implement your Lambda. struct MyLambda: SimpleLambdaHandler { // in this example we are receiving and responding with strings func handle(_ name: String, context: LambdaContext) async throws -> String { - return "Hello, \(name)" + "Hello, \(name)" } } ``` From 7738570432051bda66eb8403582eca0a78138fd8 Mon Sep 17 00:00:00 2001 From: tomer doron Date: Tue, 10 Jan 2023 09:21:35 -0800 Subject: [PATCH 4/7] Update readme.md Co-authored-by: Yim Lee --- readme.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/readme.md b/readme.md index 41fe112f..f7c24fe9 100644 --- a/readme.md +++ b/readme.md @@ -118,7 +118,7 @@ Next, create a `MyLambda.swift` and implement your Lambda. // In this example we are receiving an SQS Event, with no response (Void). @main struct MyLambda: SimpleLambdaHandler { - // In this example we are receiving and responding with `Codable`. + // In this example we are receiving a SQS Event, with no response (Void). func handle(_ event: SQS.Event, context: LambdaContext) async throws -> Void { ... } From 536dab800b63f77c66a6f233c4de7c7a20a7571e Mon Sep 17 00:00:00 2001 From: tomer doron Date: Tue, 10 Jan 2023 09:21:43 -0800 Subject: [PATCH 5/7] Update readme.md Co-authored-by: Yim Lee --- readme.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/readme.md b/readme.md index f7c24fe9..696ea90b 100644 --- a/readme.md +++ b/readme.md @@ -179,7 +179,7 @@ Next, create a `MyLambda.swift` and implement your Lambda. To deploy Lambda functions to AWS Lambda, you need to compile the code for Amazon Linux which is the OS used on AWS Lambda microVMs, package it as a Zip file, and upload to AWS. -Swift AWS Lambda Runtime includes a SwiftPM plugin designed to help with the creation of of the zip archive. +Swift AWS Lambda Runtime includes a SwiftPM plugin designed to help with the creation of the zip archive. To build and package your Lambda, run the following command: ```shell From 44409c372742ebeaf5a509f255cde2140fc14b9f Mon Sep 17 00:00:00 2001 From: tomer doron Date: Tue, 10 Jan 2023 09:22:38 -0800 Subject: [PATCH 6/7] Update readme.md --- readme.md | 1 - 1 file changed, 1 deletion(-) diff --git a/readme.md b/readme.md index 696ea90b..6b38bdf9 100644 --- a/readme.md +++ b/readme.md @@ -115,7 +115,6 @@ Next, create a `MyLambda.swift` and implement your Lambda. import AWSLambdaRuntime import AWSLambdaEvents - // In this example we are receiving an SQS Event, with no response (Void). @main struct MyLambda: SimpleLambdaHandler { // In this example we are receiving a SQS Event, with no response (Void). From 3f44810f80ace86f15279d114603dce0ae49a5f5 Mon Sep 17 00:00:00 2001 From: tomer doron Date: Tue, 10 Jan 2023 09:23:45 -0800 Subject: [PATCH 7/7] Update readme.md --- readme.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/readme.md b/readme.md index 6b38bdf9..a405778f 100644 --- a/readme.md +++ b/readme.md @@ -81,7 +81,7 @@ Next, create a `MyLambda.swift` and implement your Lambda. } ``` - Since most Lambda functions are triggered by events originating in the AWS platform like `SNS`, `SQS` or `APIGateway`, the [Swift AWS Lambda Events](http://github.com/swift-server/swift-aws-lambda-events) package includes an `AWSLambdaEvents` module that provides implementations for most common AWS event types further simplifying writing Lambda functions. For example, handling an `SQS` message: + Since most Lambda functions are triggered by events originating in the AWS platform like `SNS`, `SQS` or `APIGateway`, the [Swift AWS Lambda Events](http://github.com/swift-server/swift-aws-lambda-events) package includes an `AWSLambdaEvents` module that provides implementations for most common AWS event types further simplifying writing Lambda functions. For example, handling a `SQS` message: First, add a dependency on the event packages: