mirror of
https://github.com/swift-server/swift-aws-lambda-runtime.git
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Sébastien StormacqandTim Condon
412a345bdd
Add user-facing API for Streaming Lambda functions that receives JSON
events
### Motivation:
Streaming Lambda functions developed by developers had no choice but to
implement a handler that receives incoming data as a `ByteBuffer`. While
this is useful for low-level development, I assume most developers will
want to receive a JSON event to trigger their streaming Lambda function.
Going efficiently from a `ByteBuffer` to a Swift struct requires some
code implemented in the `JSON+ByteBuffer.swift` file of the librray. We
propose to further help developers by providing them with a new
`handler()` function that directly receives their `Decodable` type.
### Modifications:
This PR adds a public facing API (+ unit test + updated README) allowing
developers to write a handler method accepting any `Decodable` struct as
input.
```swift
import AWSLambdaRuntime
import NIOCore
// Define your input event structure
struct StreamingRequest: Decodable {
let count: Int
let message: String
let delayMs: Int?
}
// Use the new streaming handler with JSON decoding
let runtime = LambdaRuntime { (event: StreamingRequest, responseWriter, context: LambdaContext) in
context.logger.info("Received request to send \(event.count) messages")
// Stream the messages
for i in 1...event.count {
let response = "Message \(i)/\(event.count): \(event.message)\n"
try await responseWriter.write(ByteBuffer(string: response))
// Optional delay between messages
if let delay = event.delayMs, delay > 0 {
try await Task.sleep(for: .milliseconds(delay))
}
}
// Finish the stream
try await responseWriter.finish()
// Optional: Execute background work after response is sent
context.logger.info("Background work: processing completed")
}
try await runtime.run()
```
This interface provides:
- **Type-safe JSON input**: Automatic decoding of JSON events into Swift
structs
- **Streaming responses**: Full control over when and how to stream data
back to clients
- **Background work support**: Ability to execute code after the
response stream is finished
- **Familiar API**: Uses the same closure-based pattern as regular
Lambda handlers
Because streaming Lambda functions can be invoked either directly
through the API or through Lambda Function URL, this PR adds the
decoding logic to support both types, shielding developers from working
with Function URL requests and base64 encoding.
We understand these choice will have an impact on the raw performance
for event handling. Those advanced users that want to get the maximum
might use the existing `handler(_ event: ByteBuffer, writer:
LambaStreamingWriter)` function to implement their own custom decoding
logic.
This PR provides a balance between ease of use for 80% of the users vs
ultimate performance, without closing the door for the 20% who need it.
### Result:
Lambda function developers can now use arbitrary `Decodable` Swift
struct or Lambda events to trigger their streaming functions. 🎉
---------
Co-authored-by: Tim Condon <0xTim@users.noreply.github.com>
72 lines
2.8 KiB
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72 lines
2.8 KiB
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name: PR
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on:
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pull_request:
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types: [opened, reopened, synchronize]
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jobs:
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soundness:
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name: Soundness
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uses: swiftlang/github-workflows/.github/workflows/soundness.yml@main
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with:
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license_header_check_project_name: "SwiftAWSLambdaRuntime"
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shell_check_enabled: true
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python_lint_check_enabled: true
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api_breakage_check_container_image: "swiftlang/swift:nightly-6.1-jammy"
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docs_check_container_image: "swift:6.0-noble"
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format_check_container_image: "swiftlang/swift:nightly-6.1-jammy"
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yamllint_check_enabled: true
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unit-tests:
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name: Unit tests
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uses: apple/swift-nio/.github/workflows/unit_tests.yml@main
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with:
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linux_5_9_enabled: false
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linux_5_10_enabled: false
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linux_nightly_next_arguments_override: "--explicit-target-dependency-import-check error"
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linux_nightly_main_arguments_override: "--explicit-target-dependency-import-check error"
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integration-tests:
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name: Integration Tests
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uses: ./.github/workflows/integration_tests.yml
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with:
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name: "Integration tests"
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examples_enabled: true
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matrix_linux_command: "LAMBDA_USE_LOCAL_DEPS=../.. swift build"
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# We pass the list of examples here, but we can't pass an array as argument
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# Instead, we pass a String with a valid JSON array.
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# The workaround is mentioned here https://github.com/orgs/community/discussions/11692
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examples: "[ 'APIGateway', 'APIGateway+LambdaAuthorizer', 'BackgroundTasks', 'HelloJSON', 'HelloWorld', 'ResourcesPackaging', 'S3EventNotifier', 'S3_AWSSDK', 'S3_Soto', 'Streaming', 'StreamingFromEvent', 'Testing', 'Tutorial' ]"
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archive_plugin_examples: "[ 'HelloWorld', 'ResourcesPackaging' ]"
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archive_plugin_enabled: true
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swift-6-language-mode:
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name: Swift 6 Language Mode
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uses: apple/swift-nio/.github/workflows/swift_6_language_mode.yml@main
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semver-label-check:
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name: Semantic Version label check
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runs-on: ubuntu-latest
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timeout-minutes: 1
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steps:
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- name: Checkout repository
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uses: actions/checkout@v4
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with:
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persist-credentials: false
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- name: Check for Semantic Version label
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uses: apple/swift-nio/.github/actions/pull_request_semver_label_checker@main
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# until there is a support for musl in swiftlang/github-workflows
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# https://github.com/swiftlang/github-workflows/issues/34
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musl:
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runs-on: ubuntu-latest
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container: swift:6.0.2-noble
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timeout-minutes: 30
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steps:
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- name: Check out code
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uses: actions/checkout@v4
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- name: Install SDK
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run: swift sdk install https://download.swift.org/swift-6.0.2-release/static-sdk/swift-6.0.2-RELEASE/swift-6.0.2-RELEASE_static-linux-0.0.1.artifactbundle.tar.gz --checksum aa5515476a403797223fc2aad4ca0c3bf83995d5427fb297cab1d93c68cee075
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- name: Build
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run: swift build --swift-sdk x86_64-swift-linux-musl
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