Add JSON logging support using Go's slog library

README.md

@@ -16,6 +16,70 @@
 </p>
 <br>
 
+## Features
+
+- **Text Logging**: Traditional text-based logging with customizable prefixes and levels
+- **JSON Logging**: Structured JSON logging using Go's `slog` library (Go 1.21+)
+- **Level-based Filtering**: Support for TRACE, DEBUG, INFO, WARN, ERROR, and DISABLED levels
+- **Scope-based Configuration**: Different log levels for different scopes/components
+- **Environment Variable Configuration**: Configure log levels via environment variables
+- **Thread-safe**: All logging operations are thread-safe
+
+## Usage
+
+### Text Logging (Default)
+
+```go
+import "github.com/pion/logging"
+
+// Create a logger factory
+factory := logging.NewDefaultLoggerFactory()
+
+// Create loggers for different scopes
+apiLogger := factory.NewLogger("api")
+dbLogger := factory.NewLogger("database")
+
+// Log messages
+apiLogger.Info("API server started")
+apiLogger.Debug("Processing request")
+dbLogger.Error("Database connection failed")
+```
+
+### JSON Logging
+
+```go
+import "github.com/pion/logging"
+
+// Create a JSON logger factory
+factory := logging.NewJSONLoggerFactory()
+
+// Create loggers for different scopes
+apiLogger := factory.NewLogger("api")
+dbLogger := factory.NewLogger("database")
+
+// Log messages with structured data
+apiLogger.Info("API server started")
+apiLogger.Debug("Processing request", "method", "GET", "path", "/users")
+dbLogger.Error("Database connection failed", "error", "connection timeout")
+```
+
+### Environment Variable Configuration
+
+Set environment variables to configure log levels:
+
+```bash
+# Enable all log levels
+export PION_LOG_TRACE=all
+export PION_LOG_DEBUG=all
+export PION_LOG_INFO=all
+export PION_LOG_WARN=all
+export PION_LOG_ERROR=all
+
+# Enable specific scopes
+export PION_LOG_DEBUG=api,database
+export PION_LOG_INFO=feature1,feature2
+```
+
 ### Roadmap
 The library is used as a part of our WebRTC implementation. Please refer to that [roadmap](https://github.com/pion/webrtc/issues/9) to track our major milestones.
 

examples/example_json_logger.go

@@ -0,0 +1,41 @@
+// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
+// SPDX-License-Identifier: MIT
+
+package main
+
+import (
+	"os"
+
+	"github.com/pion/logging"
+)
+
+func main() {
+	// Create a JSON logger factory
+	factory := logging.NewJSONLoggerFactory(logging.WithJSONWriter(os.Stdout))
+
+	// Create loggers for different scopes
+	apiLogger := factory.NewLogger("api")
+	dbLogger := factory.NewLogger("database")
+	authLogger := factory.NewLogger("auth")
+
+	// Log some messages
+	apiLogger.Info("API server started")
+	apiLogger.Debugf("Processing request method=%s path=%s", "GET", "/users")
+	apiLogger.Warnf("Rate limit approaching requests=%d limit=%d", 95, 100)
+
+	dbLogger.Info("Database connection established")
+	dbLogger.Debugf("Executing query query=%q duration_ms=%d", "SELECT * FROM users", 15)
+
+	authLogger.Errorf("Authentication failed user_id=%s reason=%s", "12345", "invalid_token")
+	authLogger.Infof("User logged in user_id=%s ip=%s", "67890", "192.168.1.100")
+
+	// nolint:lll
+	// Example output will be JSON formatted like:
+	// {"time":"2023-12-07T10:30:00Z","level":"INFO","msg":"API server started","scope":"api"}
+	// {"time":"2023-12-07T10:30:00Z","level":"DEBUG","msg":"Processing request","scope":"api","method":"GET","path":"/users"}
+	// {"time":"2023-12-07T10:30:00Z","level":"WARN","msg":"Rate limit approaching","scope":"api","requests":95,"limit":100}
+	// {"time":"2023-12-07T10:30:00Z","level":"INFO","msg":"Database connection established","scope":"database"}
+	// {"time":"2023-12-07T10:30:00Z","level":"DEBUG","msg":"Executing query","scope":"database","query":"SELECT * FROM users","duration_ms":15}
+	// {"time":"2023-12-07T10:30:00Z","level":"ERROR","msg":"Authentication failed","scope":"auth","user_id":"12345","reason":"invalid_token"}
+	// {"time":"2023-12-07T10:30:00Z","level":"INFO","msg":"User logged in","scope":"auth","user_id":"67890","ip":"192.168.1.100"}
+}