added VaporProxy class to move the proxy code into a different class

Author: Jan Kammerath

src/Handler.swift

@@ -11,24 +11,18 @@ struct HelloWorld: Content {
 struct APIGatewayProxyLambda: LambdaHandler {
     typealias Event = APIGatewayRequest
     typealias Output = APIGatewayResponse
-
+    
     init(context: LambdaInitializationContext) async throws {
         print("Serverless Swift cold started!")
 
-        Task {
-            // instanciate the vapor application
-            let vaporApp = Vapor.Application()
-
-            // define the routes for the vapor app
-            vaporApp.get { req in
+        let vaporProxy = VaporProxy.shared
+        if !vaporProxy.isRunning() {
+            let app = vaporProxy.app
+            app.get { req in
                 return HelloWorld(message: "Hello, world!")
             }
-
-            // run the app locally, so we can proxy to it
-            let vaporAddress = BindAddress.hostname("127.0.0.1", port: 8585)
-            vaporApp.http.server.configuration.address = vaporAddress
-
-            try? vaporApp.run()
+            
+            vaporProxy.start()
         }
     }
 
@@ -37,40 +31,6 @@ struct APIGatewayProxyLambda: LambdaHandler {
         by executing the Vapor application and returning the json response
     */
     func handle(_ request: APIGatewayRequest, context: LambdaContext) async throws -> APIGatewayResponse {
-        // perform an http request to the vapor app
-        let client = HTTPClient()
-        var url = "http://127.0.0.1:8585" + request.path
-        var headers = HTTPHeaders()
-        var body: HTTPClient.Body?
-
-        let httpMethod = HTTPMethod(rawValue: request.requestContext.httpMethod)
-
-        if let queryString = request.queryStringParameters {
-            url += "?" + queryString.map { "\($0.key)=\($0.value)" }.joined(separator: "&")
-        }
-
-        if let bodyString = request.body {
-            let bodyData = Data(bodyString.utf8)
-            body = .byteBuffer(ByteBuffer(data: bodyData))
-            headers.add(name: "Content-Length", value: "\(bodyData.count)")
-            headers.add(name: "Content-Type", value: "application/json")
-        }
-
-        for (key, value) in request.headers {
-            headers.add(name: key, value: value)
-        }
-
-        let httpRequest = try HTTPClient.Request(url: url, method: httpMethod, headers: headers, body: body)
-        let response = try await client.execute(request: httpRequest).get()
-
-        let bodyString = response.body!.getString(at: 0, length: response.body!.readableBytes)
-
-        var gatewayResponse = APIGatewayResponse(statusCode: .init(code: response.status.code))
-        gatewayResponse.body = bodyString
-        for (key, value) in response.headers {
-            gatewayResponse.headers?[key] = value
-        }
-
-        return gatewayResponse
+        return try! await VaporProxy.shared.handle(request: request)
     }
 }

src/VaporProxy.swift

@@ -0,0 +1,79 @@
+import AWSLambdaEvents
+import Vapor
+
+class VaporProxy {
+    /* singleton instance of the VaporProxy class */
+    static let shared = VaporProxy()
+    
+    var app = Vapor.Application()
+    let port = 8585
+    private var running = false
+    
+    /* returns true if the vapor app is running */
+    func isRunning() -> Bool {
+        return running
+    }
+
+    /* starts the vapor app that listens on the
+        defined port. The port is used to connect
+        to the app through this proxy class */
+    func start() {
+        guard !running else {
+            print("Vapor app is already running, not starting it")
+            return
+        }
+
+        let address = BindAddress.hostname("127.0.0.1", port: 8585)
+        app.http.server.configuration.address = address
+
+        DispatchQueue.global().async {
+            do {
+                self.running = true
+                try self.app.run()
+            } catch {
+                print("Failed to start app: \(error)")
+                self.running = false
+            }
+        }
+    }
+    
+    /* handles api gateway requests and forwards them
+        to the vapor app running on the defined port */
+    func handle(request: APIGatewayRequest) async throws -> APIGatewayResponse {
+        // perform an http request to the vapor app
+        let client = HTTPClient()
+        var url = "http://127.0.0.1:\(port)" + request.path
+        var headers = HTTPHeaders()
+        var body: HTTPClient.Body?
+
+        let httpMethod = HTTPMethod(rawValue: request.requestContext.httpMethod)
+
+        if let queryString = request.queryStringParameters {
+            url += "?" + queryString.map { "\($0.key)=\($0.value)" }.joined(separator: "&")
+        }
+
+        if let bodyString = request.body {
+            let bodyData = Data(bodyString.utf8)
+            body = .byteBuffer(ByteBuffer(data: bodyData))
+            headers.add(name: "Content-Length", value: "\(bodyData.count)")
+            headers.add(name: "Content-Type", value: "application/json")
+        }
+
+        for (key, value) in request.headers {
+            headers.add(name: key, value: value)
+        }
+
+        let httpRequest = try HTTPClient.Request(url: url, method: httpMethod, headers: headers, body: body)
+        let response = try await client.execute(request: httpRequest).get()
+
+        let bodyString = response.body!.getString(at: 0, length: response.body!.readableBytes)
+
+        var gatewayResponse = APIGatewayResponse(statusCode: .init(code: response.status.code))
+        gatewayResponse.body = bodyString
+        for (key, value) in response.headers {
+            gatewayResponse.headers?[key] = value
+        }
+
+        return gatewayResponse
+    }
+}