This example shows the usage of the LambdaSwiftSprinter framework and the plugin LambdaSwiftSprinterNioPlugin to build a lambda capable to perform an Redis request using RediStack.
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
import RediStack
struct Event: Codable {
let key: String
let value: String
}
struct Response: Codable {
let value: String
}Add a loger:
let logger = Logger(label: "AWS.Lambda.Redis")Add a redis connection:
let elasticacheConfigEndpoint = "redis"
let eventLoop = httpClient.eventLoopGroup.next()
let connection = try? RedisConnection.connect(
to: try .makeAddressResolvingHost(elasticacheConfigEndpoint,
port: RedisConnection.defaultPort),
on: eventLoop
).wait()
enum LambdaError: Error {
case redisConnectionFailed
}Define the Lambda:
let syncCodableNIOLambda: SyncCodableNIOLambda<Event, Response> = { (event, context) throws -> EventLoopFuture<Response> in
guard let connection = connection else {
throw LambdaError.redisConnectionFailed
}
let future = connection.set(event.key, to: event.value)
.flatMap {
return connection.get(event.key)
}
.map { content -> Response in
return Response(value: content ?? "")
}
return future
}If there are not error, the Event will be automatically decoded inside the lambda and then used to perform a set and a get to Redis.
The value of the get is returned into the Response.
Then use this boilerplate code to run the lambda:
do {
let sprinter = try SprinterNIO()
sprinter.register(handler: "setGet", 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 setGet is being registered.
Finally the sprinter run.
Any error will be logged.
Note
In this example we used swift-log to log the output.
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=$(SWIFT_EXECUTABLE).helloWorld
....
# RedisDemo Example Configuration
SWIFT_EXECUTABLE?=RedisDemo
SWIFT_PROJECT_PATH?=Examples/RedisDemo
LAMBDA_FUNCTION_NAME?=RedisDemo
LAMBDA_HANDLER?=$(SWIFT_EXECUTABLE).setGet
...
Then follow the main README to build and test the code.
The test event is defined in the file event.json
{
"key": "language",
"value": "Swift"
}expected response:
{"value":"Swift"}Change it to try different output and error conditions.
To know more refer to LambdaSwiftSprinter.