Adds support for metadata providers (#12)

* feat: add metadata provider support

* test: add test for metadata subscript

Package.resolved

@@ -140,8 +140,8 @@
       "kind" : "remoteSourceControl",
       "location" : "https://github.com/apple/swift-protobuf.git",
       "state" : {
-        "revision" : "ab3a58b7209a17d781c0d1dbb3e1ff3da306bae8",
-        "version" : "1.20.3"
+        "revision" : "9f0c76544701845ad98716f3f6a774a892152bcb",
+        "version" : "1.26.0"
       }
     },
     {

Package.swift

@@ -3,7 +3,7 @@ import PackageDescription
 
 let package = Package(
     name: "swift-log-loki",
-    platforms: [.macOS(.v14), .iOS(.v17), .tvOS(.v17), .watchOS(.v9), .visionOS(.v1)],
+    platforms: [.macOS(.v14), .iOS(.v17), .tvOS(.v17), .watchOS(.v10), .visionOS(.v1)],
     products: [
         .library(name: "LoggingLoki", targets: ["LoggingLoki"]),
     ],

README.md

@@ -2,7 +2,8 @@
 
 [![Coverage](https://codecov.io/gh/lovetodream/swift-log-loki/graph/badge.svg?token=Q70PZWS0T2)](https://codecov.io/gh/lovetodream/swift-log-loki)
 [![Tests](https://github.com/lovetodream/swift-log-loki/actions/workflows/tests.yml/badge.svg)](https://github.com/lovetodream/swift-log-loki/actions/workflows/tests.yml)
-[![Docs](https://github.com/lovetodream/swift-log-loki/actions/workflows/deploy_docs.yml/badge.svg)](https://github.com/lovetodream/swift-log-loki/actions/workflows/deploy_docs.yml)
+[![Swift Versions](https://img.shields.io/endpoint?url=https%3A%2F%2Fswiftpackageindex.com%2Fapi%2Fpackages%2Flovetodream%2Fswift-log-loki%2Fbadge%3Ftype%3Dswift-versions)](https://swiftpackageindex.com/lovetodream/swift-log-loki)
+[![Supported Platforms](https://img.shields.io/endpoint?url=https%3A%2F%2Fswiftpackageindex.com%2Fapi%2Fpackages%2Flovetodream%2Fswift-log-loki%2Fbadge%3Ftype%3Dplatforms)](https://swiftpackageindex.com/lovetodream/swift-log-loki)
 
 This library can be used as an implementation of Apple's [swift-log](https://github.com/apple/swift-log) interface that captures console logs from apps or services and sends them to [Grafana Loki](https://grafana.com/oss/loki).
 
@@ -59,7 +60,7 @@ try await withThrowingDiscardingTaskGroup { group in
 
 ## API documentation
 
-For more information visit the [API reference](https://timozacherl.com/swift-log-loki/documentation/loggingloki/).
+For more information visit the [API reference](https://swiftpackageindex.com/lovetodream/swift-log-loki/documentation/loggingloki).
 
 ## License
 

Sources/LoggingLoki/LokiLogHandler.swift

@@ -17,6 +17,8 @@ public struct LokiLogHandler<Clock: _Concurrency.Clock>: LogHandler, Sendable wh
     /// Static labels sent to Loki, which should not depend on the context of a log message.
     public var lokiLabels: [String: String]
 
+    public var metadataProvider: Logger.MetadataProvider?
+
     /// Creates a log handler, which sends logs to Grafana Loki.
     ///
     /// @Snippet(path: "swift-log-loki/Snippets/BasicUsage", slice: "setup")
@@ -28,16 +30,19 @@ public struct LokiLogHandler<Clock: _Concurrency.Clock>: LogHandler, Sendable wh
     ///              It will be sent to Loki as the `service` label.
     ///   - lokiLabels: Static labels sent to Loki, which should not depend on the context of a log message.
     ///   - processor: Backend service which manages and sends logs to Loki.
+    ///   - metadataProvider: A MetadataProvider, used to automatically inject runtime-generated metadata to all logs.
     public init(
         label: String,
         service: String = ProcessInfo.processInfo.processName,
         lokiLabels: [String: String] = [:],
-        processor: LokiLogProcessor<Clock>
+        processor: LokiLogProcessor<Clock>,
+        metadataProvider: Logger.MetadataProvider? = nil
     ) {
         self.label = label
         self.service = service
         self.lokiLabels = lokiLabels
         self.processor = processor
+        self.metadataProvider = metadataProvider
     }
 
     /// This method is called when a `LogHandler` must emit a log message. There is no need for the `LogHandler` to

Tests/LoggingLokiTests/LokiLogHandlerTests.swift

@@ -138,6 +138,29 @@ final class LokiLogHandlerTests: XCTestCase {
         processing.cancel()
     }
 
+    func testMetadataPreparation() {
+        let metadata1 = LokiLogHandler<TestClock>.prepareMetadata(base: [:], provider: .init({ [:] }), explicit: [:])
+        XCTAssertEqual(metadata1, [:])
+        let metadata2 = LokiLogHandler<TestClock>.prepareMetadata(base: ["hello": "there"], provider: .init({ [:] }), explicit: [:])
+        XCTAssertEqual(metadata2, ["hello": "there"])
+        let metadata3 = LokiLogHandler<TestClock>.prepareMetadata(base: ["hello": "there"], provider: .init({ ["provided": "metadata"] }), explicit: [:])
+        XCTAssertEqual(metadata3, ["hello": "there", "provided": "metadata"])
+        let metadata4 = LokiLogHandler<TestClock>.prepareMetadata(base: ["hello": "there"], provider: .init({ ["provided": "metadata"] }), explicit: ["explicit": "metadata"])
+        XCTAssertEqual(metadata4, ["hello": "there", "provided": "metadata", "explicit": "metadata"])
+        let metadata5 = LokiLogHandler<TestClock>.prepareMetadata(base: ["hello": "there"], provider: nil, explicit: ["explicit": "metadata"])
+        XCTAssertEqual(metadata5, ["hello": "there", "explicit": "metadata"])
+        let metadata6 = LokiLogHandler<TestClock>.prepareMetadata(base: ["hello": "there"], provider: nil, explicit: nil)
+        XCTAssertEqual(metadata6, ["hello": "there"])
+        let metadata7 = LokiLogHandler<TestClock>.prepareMetadata(base: ["hello": "there"], provider: .init({ ["hello": "how are you"] }), explicit: nil)
+        XCTAssertEqual(metadata7, ["hello": "how are you"])
+        let metadata8 = LokiLogHandler<TestClock>.prepareMetadata(base: ["hello": "there"], provider: .init({ ["hello": "how are you"] }), explicit: ["hello": "I am fine"])
+        XCTAssertEqual(metadata8, ["hello": "I am fine"])
+        var handler = LokiLogHandler(label: "test", processor: .init(configuration: .init(lokiURL: "")))
+        handler[metadataKey: "key"] = "value"
+        XCTAssertEqual(handler.metadata, ["key": "value"])
+        XCTAssertEqual(handler[metadataKey: "key"], "value")
+    }
+
     func checkIfLogExists(for transformer: TestTransformer, file: StaticString = #filePath, line: UInt = #line) throws {
         let firstLog = try XCTUnwrap(transformer.logs?.first, file: file, line: line)