iOS: Logging Part 2 – Basic File Persistence

mobile/TeleportKit/.swiftpm/xcode/xcshareddata/xcschemes/LogBackends.xcscheme

@@ -0,0 +1,66 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Scheme
+   LastUpgradeVersion = "2700"
+   version = "1.7">
+   <BuildAction
+      parallelizeBuildables = "YES"
+      buildImplicitDependencies = "YES"
+      buildArchitectures = "Automatic">
+      <BuildActionEntries>
+         <BuildActionEntry
+            buildForTesting = "YES"
+            buildForRunning = "YES"
+            buildForProfiling = "YES"
+            buildForArchiving = "YES"
+            buildForAnalyzing = "YES">
+            <BuildableReference
+               BuildableIdentifier = "primary"
+               BlueprintIdentifier = "LogBackends"
+               BuildableName = "LogBackends"
+               ReferencedContainer = "container:">
+            </BuildableReference>
+         </BuildActionEntry>
+      </BuildActionEntries>
+   </BuildAction>
+   <TestAction
+      buildConfiguration = "Debug"
+      selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
+      selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      shouldUseLaunchSchemeArgsEnv = "YES"
+      shouldAutocreateTestPlan = "YES">
+   </TestAction>
+   <LaunchAction
+      buildConfiguration = "Debug"
+      selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
+      selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      launchStyle = "0"
+      useCustomWorkingDirectory = "NO"
+      ignoresPersistentStateOnLaunch = "NO"
+      debugDocumentVersioning = "YES"
+      debugServiceExtension = "internal"
+      allowLocationSimulation = "YES"
+      queueDebuggingEnabled = "No">
+   </LaunchAction>
+   <ProfileAction
+      buildConfiguration = "Release"
+      shouldUseLaunchSchemeArgsEnv = "YES"
+      savedToolIdentifier = ""
+      useCustomWorkingDirectory = "NO"
+      debugDocumentVersioning = "YES">
+      <MacroExpansion>
+         <BuildableReference
+            BuildableIdentifier = "primary"
+            BlueprintIdentifier = "LogBackends"
+            BuildableName = "LogBackends"
+            ReferencedContainer = "container:">
+         </BuildableReference>
+      </MacroExpansion>
+   </ProfileAction>
+   <AnalyzeAction
+      buildConfiguration = "Debug">
+   </AnalyzeAction>
+   <ArchiveAction
+      buildConfiguration = "Release"
+      revealArchiveInOrganizer = "YES">
+   </ArchiveAction>
+</Scheme>

mobile/TeleportKit/Package.swift

@@ -4,7 +4,7 @@ import PackageDescription
 
 let package = Package(
 	name: "TeleportKit",
-	platforms: [.iOS(.v26)],
+	platforms: [.iOS(.v26), .macOS(.v26)],
 	products: [
 		.library(name: "SystemClients", targets: ["SystemClients"]),
 		.library(name: "LogBackends", targets: ["LogBackends"]),
@@ -13,6 +13,7 @@ let package = Package(
 		.package(url: "https://github.com/pointfreeco/swift-dependencies", .upToNextMajor(from: "1.14.0")),
 		.package(url: "https://github.com/pointfreeco/swift-sharing", .upToNextMajor(from: "2.9.1")),
 		.package(url: "https://github.com/apple/swift-log", .upToNextMajor(from: "1.14.0")),
+		.package(url: "https://github.com/apple/swift-collections", .upToNextMajor(from: "1.6.0")),
 	],
 	targets: [
 		.target(
@@ -26,7 +27,19 @@ let package = Package(
 		.target(
 			name: "LogBackends",
 			dependencies: [
+				.collections,
 				.logging,
+				.dependencies,
+				"SystemClients",
+			],
+		),
+		.testTarget(
+			name: "LogBackendsTests",
+			dependencies: [
+				.dependencies,
+				.logging,
+				"LogBackends",
+				"SystemClients",
 			],
 		),
 	],
@@ -52,6 +65,10 @@ extension Target.Dependency {
 		name: "Logging",
 		package: "swift-log",
 	)
+	fileprivate static let collections: Self = .product(
+		name: "Collections",
+		package: "swift-collections",
+	)
 }
 
 // MARK: - Build Settings

mobile/TeleportKit/Sources/LogBackends/ConsoleLogHandler.swift

@@ -14,13 +14,17 @@
 // You should have received a copy of the GNU Affero General Public License
 // along with this program.  If not, see http://www.gnu.org/licenses/
 
+import Dependencies
 import Foundation
 public import Logging
 
 /// A simple print-based log handler primarily used for live debugging sessions.
 public struct ConsoleLogHandler: LogHandler {
 	public let label: String
 
+	@Dependency(\.date.now)
+	private var now
+
 	private let timestampFormmater = Date.ISO8601FormatStyle(
 		dateSeparator: .dash,
 		dateTimeSeparator: .space,
@@ -46,11 +50,7 @@ public struct ConsoleLogHandler: LogHandler {
 	}
 
 	public func log(event: LogEvent) {
-		let timestamp = timestampFormmater.format(.now)
-		let metadataToLog = metadata.merging(event.metadata ?? [:]) { _, new in new }
-
-		let output = "\(timestamp) \(event.level.formatted) \(event.file):\(event.line) | \(event.message) \(metadataToLog.formatted)"
-
-		print(output)
+		let logMessage = LogFormatter.format(label: label, event: event, handlerMetadata: metadata, timestamp: now)
+		print(logMessage)
 	}
 }

mobile/TeleportKit/Sources/LogBackends/Formatting/LogFormatter.swift

@@ -0,0 +1,67 @@
+// Teleport
+// Copyright (C) 2026 Gravitational, Inc.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see http://www.gnu.org/licenses/
+
+import Foundation
+import Logging
+
+/// LogFormatter doesn't currently maintain any local state, so it's simplest to implement it as an enum with static
+/// functions.
+enum LogFormatter {
+	private static let timestampFormatter = Date.ISO8601FormatStyle(
+		dateSeparator: .dash,
+		dateTimeSeparator: .space,
+		timeSeparator: .colon,
+		timeZoneSeparator: .colon,
+		includingFractionalSeconds: true,
+		timeZone: .autoupdatingCurrent,
+	)
+
+	/// Formats the log message
+	/// - Parameters:
+	///   - label: The label of the logger
+	///   - event: The event to log
+	///   - handlerMetadata: The metadata for the `LogHandler` (note: events carry their own metadata and this formatter
+	/// 	automatically coalesces them with the `LogHandler` metadata)
+	///   - timestamp: The time at which the logging event took place
+	/// - Returns: A formatted log message suitable for output to a debug console or writing to a file
+	static func format(
+		label: String,
+		event: LogEvent,
+		handlerMetadata: Logger.Metadata,
+		timestamp: Date,
+	) -> String {
+		let metadata = handlerMetadata.merging(event.metadata ?? [:]) { _, eventValue in eventValue }
+		var components: [String] = [
+			timestampFormatter.format(timestamp),
+			event.level.formatted,
+			"[\(label)]",
+			"\(event.file):\(event.line)",
+			"|",
+			"\(event.message)",
+		]
+
+		let formattedMetadata = metadata.formatted
+		if !formattedMetadata.isEmpty {
+			components.append(formattedMetadata)
+		}
+
+		if let error = event.error {
+			components.append("❌ error=\(error)")
+		}
+
+		return components.joined(separator: " ")
+	}
+}

mobile/TeleportKit/Sources/LogBackends/Metadata+Formatting.swift → mobile/TeleportKit/Sources/LogBackends/Formatting/Metadata+Formatting.swift

@@ -25,12 +25,7 @@ extension Logger.Metadata {
 	var formatted: String {
 		guard !isEmpty else { return "" }
 		let metadataAsStrings = map { key, value in
-			let prefix = if key.lowercased().localizedStandardContains("error") {
-				"❌"
-			} else {
-				"🔸"
-			}
-			return "\(prefix) \(key)=\(value)"
+			"🔸 \(key)=\(value)"
 		}
 		return metadataAsStrings.joined(separator: " ")
 	}

mobile/TeleportKit/Sources/LogBackends/Rotating File/RotatingFileLogHandler.swift

@@ -0,0 +1,50 @@
+// Teleport
+// Copyright (C) 2026 Gravitational, Inc.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see http://www.gnu.org/licenses/
+
+import Dependencies
+import Foundation
+import Logging
+
+/// A log handler that writes to a rotating file on disk.
+public struct RotatingFileLogHandler: LogHandler {
+	public let label: String
+
+	@Dependency(\.date.now)
+	private var now
+
+	private let writer: RotatingFileWriter
+
+	public init(label: String, writer: RotatingFileWriter) {
+		self.label = label
+		self.writer = writer
+	}
+
+	// MARK: LogHandler Conformance
+
+	public var logLevel: Logger.Level = .info
+
+	public var metadata: Logger.Metadata = [:]
+
+	public subscript(metadataKey key: String) -> Logger.Metadata.Value? {
+		get { metadata[key] }
+		set { metadata[key] = newValue }
+	}
+
+	public func log(event: LogEvent) {
+		let logMessage = LogFormatter.format(label: label, event: event, handlerMetadata: metadata, timestamp: now)
+		writer.enqueue(logMessage: "\(logMessage)\n")
+	}
+}