Default to enabled observability (#54)

### Motivation

Swift Log/Swift Metrics integration should be enabled by default. And
the operator can always pass in a no-op log/metrics backend if they want
to discard it.

This is important when Configuration is used as a transitive dependency,
as there the operator wouldn't have a way to _enable_ observability from
this library unless the direct dependency that pulled in Configuration
was cooperative.

### Modifications

Enabled logging/metrics by default by changing the default parameter
values in the reloading providers.

### Result

Logs/metrics emitted for reloading providers by default.

### Test Plan

Adapted tests.

Author: czechboy0

.gitignore

@@ -7,3 +7,4 @@ DerivedData/
 Package.resolved
 *.pyc
 .docc-build
+.vscode

Sources/Configuration/Providers/Common/ReloadingFileProviderCore.swift

@@ -94,17 +94,17 @@ internal final class ReloadingFileProviderCore<SnapshotType: ConfigSnapshotProto
     ///   - pollInterval: The interval between timestamp checks.
     ///   - providerName: The human-readable name of the provider.
     ///   - fileSystem: The file system to use.
-    ///   - logger: The logger instance, or nil to create a default one.
-    ///   - metrics: The metrics factory, or nil to use a no-op implementation.
+    ///   - logger: The logger instance.
+    ///   - metrics: The metrics factory.
     ///   - createSnapshot: A closure that creates a snapshot from file data.
     /// - Throws: If the initial file load or snapshot creation fails.
     internal init(
         filePath: FilePath,
         pollInterval: Duration,
         providerName: String,
         fileSystem: any CommonProviderFileSystem,
-        logger: Logger?,
-        metrics: (any MetricsFactory)?,
+        logger: Logger,
+        metrics: any MetricsFactory,
         createSnapshot: @Sendable @escaping (Data) async throws -> SnapshotType
     ) async throws {
         self.filePath = filePath
@@ -114,7 +114,7 @@ internal final class ReloadingFileProviderCore<SnapshotType: ConfigSnapshotProto
         self.createSnapshot = createSnapshot
 
         // Set up the logger with metadata
-        var logger = logger ?? Logger(label: providerName)
+        var logger = logger
         logger[metadataKey: "\(providerName).filePath"] = .string(filePath.lastComponent?.string ?? "<nil>")
         logger[metadataKey: "\(providerName).pollInterval.seconds"] = .string(
             pollInterval.components.seconds.description
@@ -123,7 +123,7 @@ internal final class ReloadingFileProviderCore<SnapshotType: ConfigSnapshotProto
 
         // Set up metrics
         self.metrics = ReloadingFileProviderMetrics(
-            factory: metrics ?? NOOPMetricsHandler.instance,
+            factory: metrics,
             providerName: providerName
         )
 

Sources/Configuration/Providers/JSON/ReloadingJSONProvider.swift

@@ -95,8 +95,8 @@ public final class ReloadingJSONProvider: Sendable {
         pollInterval: Duration = .seconds(15),
         bytesDecoder: some ConfigBytesFromStringDecoder = .base64,
         secretsSpecifier: SecretsSpecifier<String, any Sendable> = .none,
-        logger: Logger? = nil,
-        metrics: (any MetricsFactory)? = nil
+        logger: Logger = Logger(label: "ReloadingJSONProvider"),
+        metrics: any MetricsFactory = MetricsSystem.factory
     ) async throws {
         try await self.init(
             filePath: filePath,
@@ -116,17 +116,17 @@ public final class ReloadingJSONProvider: Sendable {
     ///   - bytesDecoder: A decoder of bytes from a string.
     ///   - secretsSpecifier: A secrets specifier in case some of the values should be treated as secret.
     ///   - fileSystem: The underlying file system.
-    ///   - logger: The logger instance to use, or nil to create a default one.
-    ///   - metrics: The metrics factory to use, or nil to use a no-op implementation.
+    ///   - logger: The logger instance to use.
+    ///   - metrics: The metrics factory to use.
     /// - Throws: If the file cannot be read or parsed, or if the JSON structure is invalid.
     internal init(
         filePath: FilePath,
         pollInterval: Duration,
         bytesDecoder: some ConfigBytesFromStringDecoder,
         secretsSpecifier: SecretsSpecifier<String, any Sendable>,
         fileSystem: some CommonProviderFileSystem,
-        logger: Logger?,
-        metrics: (any MetricsFactory)?
+        logger: Logger,
+        metrics: any MetricsFactory
     ) async throws {
         self.core = try await ReloadingFileProviderCore(
             filePath: filePath,
@@ -189,8 +189,8 @@ public final class ReloadingJSONProvider: Sendable {
         config: ConfigReader,
         bytesDecoder: some ConfigBytesFromStringDecoder = .base64,
         secretsSpecifier: SecretsSpecifier<String, any Sendable> = .none,
-        logger: Logger? = nil,
-        metrics: (any MetricsFactory)? = nil
+        logger: Logger = Logger(label: "ReloadingJSONProvider"),
+        metrics: any MetricsFactory = MetricsSystem.factory
     ) async throws {
         try await self.init(
             filePath: config.requiredString(forKey: "filePath", as: FilePath.self),

Sources/Configuration/Providers/YAML/ReloadingYAMLProvider.swift

@@ -92,16 +92,16 @@ public final class ReloadingYAMLProvider: Sendable {
     ///   - pollInterval: The interval between file modification checks. Defaults to 15 seconds.
     ///   - bytesDecoder: The decoder used to convert string values to byte arrays.
     ///   - secretsSpecifier: Specifies which configuration values should be treated as secrets.
-    ///   - logger: The logger instance to use, or nil to create a default one.
-    ///   - metrics: The metrics factory to use, or nil to use a no-op implementation.
+    ///   - logger: The logger instance to use.
+    ///   - metrics: The metrics factory to use.
     /// - Throws: If the file cannot be read or parsed, or if the YAML structure is invalid.
     public convenience init(
         filePath: FilePath,
         pollInterval: Duration = .seconds(15),
         bytesDecoder: some ConfigBytesFromStringDecoder = .base64,
         secretsSpecifier: SecretsSpecifier<String, Void> = .none,
-        logger: Logger? = nil,
-        metrics: (any MetricsFactory)? = nil
+        logger: Logger = Logger(label: "ReloadingYAMLProvider"),
+        metrics: any MetricsFactory = MetricsSystem.factory
     ) async throws {
         try await self.init(
             filePath: filePath,
@@ -121,17 +121,17 @@ public final class ReloadingYAMLProvider: Sendable {
     ///   - bytesDecoder: A decoder of bytes from a string.
     ///   - secretsSpecifier: A secrets specifier in case some of the values should be treated as secret.
     ///   - fileSystem: The underlying file system.
-    ///   - logger: The logger instance to use, or nil to create a default one.
-    ///   - metrics: The metrics factory to use, or nil to use a no-op implementation.
+    ///   - logger: The logger instance to use.
+    ///   - metrics: The metrics factory to use.
     /// - Throws: If the file cannot be read or parsed, or if the YAML structure is invalid.
     internal init(
         filePath: FilePath,
         pollInterval: Duration,
         bytesDecoder: some ConfigBytesFromStringDecoder,
         secretsSpecifier: SecretsSpecifier<String, Void>,
         fileSystem: some CommonProviderFileSystem,
-        logger: Logger?,
-        metrics: (any MetricsFactory)?
+        logger: Logger,
+        metrics: any MetricsFactory
     ) async throws {
         self.core = try await ReloadingFileProviderCore(
             filePath: filePath,
@@ -186,15 +186,15 @@ public final class ReloadingYAMLProvider: Sendable {
     ///   - config: The configuration reader containing the file path.
     ///   - bytesDecoder: The decoder used to convert string values to byte arrays.
     ///   - secretsSpecifier: Specifies which configuration values should be treated as secrets.
-    ///   - logger: The logger instance to use, or nil to create a default one.
-    ///   - metrics: The metrics factory to use, or nil to use a no-op implementation.
+    ///   - logger: The logger instance to use.
+    ///   - metrics: The metrics factory to use.
     /// - Throws: If the file path is missing, or if the file cannot be read or parsed.
     public convenience init(
         config: ConfigReader,
         bytesDecoder: some ConfigBytesFromStringDecoder = .base64,
         secretsSpecifier: SecretsSpecifier<String, Void> = .none,
-        logger: Logger? = nil,
-        metrics: (any MetricsFactory)? = nil
+        logger: Logger = Logger(label: "ReloadingYAMLProvider"),
+        metrics: any MetricsFactory = MetricsSystem.factory
     ) async throws {
         try await self.init(
             filePath: config.requiredString(forKey: "filePath", as: FilePath.self),

Tests/ConfigurationTests/ReloadingFileProviderCoreTests.swift

@@ -20,6 +20,7 @@ import ConfigurationTestingInternal
 import Foundation
 import ConfigurationTesting
 import Logging
+import Metrics
 import ServiceLifecycle
 import Synchronization
 import SystemPackage
@@ -97,7 +98,7 @@ private func withTestProvider<R>(
         providerName: "TestProvider",
         fileSystem: fileSystem,
         logger: .noop,
-        metrics: nil,
+        metrics: NOOPMetricsHandler.instance,
         createSnapshot: { data in
             try TestSnapshot(contents: String(decoding: data, as: UTF8.self))
         }
@@ -155,7 +156,7 @@ struct CoreTests {
             providerName: "TestProvider",
             fileSystem: fileSystem,
             logger: .noop,
-            metrics: nil,
+            metrics: NOOPMetricsHandler.instance,
             createSnapshot: { data in
                 try TestSnapshot(contents: String(decoding: data, as: UTF8.self))
             }