HTTPSRequest

HTTPSRequest

This example shows the usage of the LambdaSwiftSprinter framework and the plugin LambdaSwiftSprinterNioPlugin to build a lambda capable to perform an HTTPS request.

Swift code

Define an Event and a Response as Codable.

import AsyncHTTPClient
import Foundation
#if canImport(FoundationNetworking)
    import FoundationNetworking
#endif
import LambdaSwiftSprinter
import LambdaSwiftSprinterNioPlugin
import Logging
import NIO
import NIOFoundationCompat

struct Event: Codable {
    let url: String
}

struct Response: Codable {
    let url: String
    let content: String
}

Add a loger:

let logger = Logger(label: "AWS.Lambda.HTTPSRequest")

Define the lambda:

let syncCodableNIOLambda: SyncCodableNIOLambda<Event, Response> = { (event, context) throws -> EventLoopFuture<Response> in
    
    let request = try HTTPClient.Request(url: event.url)
    let future = httpClient.execute(request: request, deadline: nil)
        .flatMapThrowing { (response) throws -> String in
                guard let body = response.body,
                    let value = body.getString(at: 0, length: body.readableBytes) else {
                        throw SprinterError.invalidJSON
            }
            return value
        }.map { content -> Response in
            return Response(url: event.url, content: content)
        }
    return future
}

If there are not error, the Event will be automatically decoded inside the lambda and then used to perform a https request to the url received. The response of the https request is returned into the Response. This lambda is synchronous, meaning that all the operation are performed on the same lambda thread.

Then use this boilerplate code to run the lambda:

do {
    let sprinter = try SprinterNIO()
    sprinter.register(handler: "getHttps", lambda: syncCodableNIOLambda)
    
    try sprinter.run()
} catch {
    logger.error("\(String(describing: error))")
}

This will initialize the Sprinter with a Sprinter based on NIO 2 library.

Then the internal handler getHttps is being registered.

Finally the sprinter run.

Any error will be logged.

Note

In this example we used swift-log to log the output.

Deployment

To build this example make sure the following lines on the Makefile are not commented and the other example configurations are commented.

...

# HelloWorld Example Configuration
# SWIFT_EXECUTABLE=HelloWorld
# SWIFT_PROJECT_PATH=Examples/HelloWorld
# LAMBDA_FUNCTION_NAME=HelloWorld
# LAMBDA_HANDLER=$(SWIFT_EXECUTABLE).helloWorld

# HTTPSRequest Example Configuration
SWIFT_EXECUTABLE=HTTPSRequest
SWIFT_PROJECT_PATH=Examples/HTTPSRequest
LAMBDA_FUNCTION_NAME=HTTPSRequest
LAMBDA_HANDLER=$(SWIFT_EXECUTABLE).getHttps

# S3Test Example Configuration
# SWIFT_EXECUTABLE=S3Test
# SWIFT_PROJECT_PATH=Examples/S3Test
# LAMBDA_FUNCTION_NAME=S3Test
# LAMBDA_HANDLER=$(SWIFT_EXECUTABLE).getObject

...

Then follow the main README to build and test the code.

Test

The test event is defined in the file event.json

{
    "url": "https://swift.org"
}

expected response:

{
    "url": "https://swift.org",
    "content": "<THE HTML PAGE FROM swift.org>"
}

Change it to try different output and error conditions.

LambdaSwiftSprinter

To know more refer to LambdaSwiftSprinter.