Add Logger support

Author: adam-fowler

Package.resolved

@@ -8,13 +8,15 @@ let package = Package(
         .library(name: "MQTTNIO", targets: ["MQTTNIO"]),
     ],
     dependencies: [
+        .package(url: "https://github.com/apple/swift-log.git", from: "1.0.0"),
         .package(url: "https://github.com/apple/swift-nio.git", from: "2.21.0"),
         .package(url: "https://github.com/apple/swift-nio-ssl.git", from: "2.10.0"),
-            .package(url: "https://github.com/apple/swift-nio-transport-services.git", from: "1.6.0")
+        .package(url: "https://github.com/apple/swift-nio-transport-services.git", from: "1.6.0")
     ],
     targets: [
         .target(name: "MQTTNIO", dependencies: [
             .byName(name: "CCoreMQTT"),
+            .product(name: "Logging", package: "swift-log"),
             .product(name: "NIO", package: "swift-nio"),
             .product(name: "NIOHTTP1", package: "swift-nio"),
             .product(name: "NIOWebSocket", package: "swift-nio"),

Package.swift

@@ -13,7 +13,7 @@ final class MQTTEncodeHandler: ChannelOutboundHandler {
 
     func write(context: ChannelHandlerContext, data: NIOAny, promise: EventLoopPromise<Void>?) {
         let message = unwrapOutboundIn(data)
-        print("\(client.clientIdentifier) Out: \(message)")
+        client.logger.debug("MQTT Out", metadata: ["mqtt_client": .string(client.clientIdentifier), "mqtt_message": .string("\(message)")])
         var bb = context.channel.allocator.buffer(capacity: 0)
         try! message.serialize(to: &bb)
         context.write(wrapOutboundOut(bb), promise: promise)
@@ -39,7 +39,7 @@ struct ByteToMQTTMessageDecoder: ByteToMessageDecoder {
                 do {
                     let publish = try MQTTSerializer.readPublish(from: packet)
                     let publishMessage = MQTTPublishMessage(publish: publish.publishInfo, packetId: publish.packetId)
-                    print("\(client.clientIdentifier) In: \(publishMessage)")
+                    client.logger.debug("MQTT In", metadata: ["mqtt_client": .string(client.clientIdentifier), "mqtt_message": .string("\(publishMessage)")])
                     self.publish(publishMessage)
                 } catch MQTTSerializer.Error.incompletePacket {
                     return .needMoreData
@@ -58,7 +58,7 @@ struct ByteToMQTTMessageDecoder: ByteToMessageDecoder {
             default:
                 throw MQTTClient.Error.decodeError
             }
-            print("\(client.clientIdentifier) In: \(message)")
+            client.logger.debug("MQTT In", metadata: ["mqtt_client": .string(client.clientIdentifier), "mqtt_message": .string("\(message)")])
             context.fireChannelRead(wrapInboundOut(message))
         } catch MQTTSerializer.Error.incompletePacket {
             return .needMoreData

Sources/MQTTNIO/MQTTChannelHandlers.swift

@@ -1,4 +1,5 @@
 import Foundation
+import Logging
 #if canImport(Network)
 import Network
 #endif
@@ -29,6 +30,8 @@ public class MQTTClient {
     let host: String
     /// Port to connect to
     let port: Int
+    /// logger
+    let logger: Logger
     /// Client configuration
     let configuration: Configuration
     /// Called whenever a publish event occurs
@@ -40,6 +43,8 @@ public class MQTTClient {
     var clientIdentifier = ""
 
     private static let globalPacketId = NIOAtomic<UInt16>.makeAtomic(value: 1)
+    /// default logger that logs nothing
+    private static let loggingDisabled = Logger(label: "MQTT-do-not-log", factory: { _ in SwiftLogNoOpLogHandler() })
 
     /// Configuration for MQTTClient
     public struct Configuration {
@@ -88,6 +93,7 @@ public class MQTTClient {
         host: String,
         port: Int? = nil,
         eventLoopGroupProvider: NIOEventLoopGroupProvider,
+        logger: Logger? = nil,
         configuration: Configuration = Configuration(),
         publishCallback: @escaping (Result<MQTTPublishInfo, Swift.Error>) -> () = { _ in }
     ) {
@@ -109,6 +115,7 @@ public class MQTTClient {
         self.configuration = configuration
         self.publishCallback = publishCallback
         self.channel = nil
+        self.logger = logger ?? Self.loggingDisabled
         self.eventLoopGroupProvider = eventLoopGroupProvider
         switch eventLoopGroupProvider {
         case .createNew:

Sources/MQTTNIO/MQTTClient.swift

@@ -1,11 +1,18 @@
 import XCTest
+import Logging
 import NIO
 import NIOHTTP1
 import NIOSSL
 @testable import MQTTNIO
 
 final class MQTTNIOTests: XCTestCase {
 
+    let logger: Logger = {
+        var logger = Logger(label: "MQTTTests")
+        logger.logLevel = .trace
+        return logger
+    }()
+
     // downloaded from http://test.mosquitto.org/
     let mosquittoCertificate = """
     -----BEGIN CERTIFICATE-----
@@ -35,13 +42,20 @@ final class MQTTNIOTests: XCTestCase {
     """
 
     func createClient(cb: @escaping (Result<MQTTPublishInfo, Swift.Error>) -> () = { _ in }) -> MQTTClient {
-        MQTTClient(host: "test.mosquitto.org", port: 1883, eventLoopGroupProvider: .createNew, publishCallback: cb)
+        MQTTClient(
+            host: "test.mosquitto.org",
+            port: 1883,
+            eventLoopGroupProvider: .createNew,
+            logger: self.logger,
+            publishCallback: cb
+        )
     }
     func createWebSocketClient(cb: @escaping (Result<MQTTPublishInfo, Swift.Error>) -> () = { _ in }) -> MQTTClient {
         MQTTClient(
             host: "test.mosquitto.org",
             port: 8080,
             eventLoopGroupProvider: .createNew,
+            logger: self.logger,
             configuration: .init(useWebSockets: true, webSocketURLPath: "/mqtt"),
             publishCallback: cb
         )
@@ -55,6 +69,7 @@ final class MQTTNIOTests: XCTestCase {
             host: "test.mosquitto.org",
             port: 8883,
             eventLoopGroupProvider: .createNew,
+            logger: self.logger,
             configuration: .init(useSSL: true, tlsConfiguration: tlsConfiguration),
             publishCallback: cb
         )