Initial commit: logcorrelator with unified packaging (DEB + RPM using fpm)

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

internal/observability/logger.go

@@ -0,0 +1,85 @@
+package observability
+
+import (
+	"log"
+	"os"
+	"sync"
+)
+
+// Logger provides structured logging.
+type Logger struct {
+	mu       sync.Mutex
+	logger   *log.Logger
+	prefix   string
+	fields   map[string]any
+}
+
+// NewLogger creates a new logger.
+func NewLogger(prefix string) *Logger {
+	return &Logger{
+		logger: log.New(os.Stderr, "", log.LstdFlags|log.Lmicroseconds),
+		prefix: prefix,
+		fields: make(map[string]any),
+	}
+}
+
+// WithFields returns a new logger with additional fields.
+func (l *Logger) WithFields(fields map[string]any) *Logger {
+	newLogger := &Logger{
+		logger: l.logger,
+		prefix: l.prefix,
+		fields: make(map[string]any),
+	}
+	for k, v := range l.fields {
+		newLogger.fields[k] = v
+	}
+	for k, v := range fields {
+		newLogger.fields[k] = v
+	}
+	return newLogger
+}
+
+// Info logs an info message.
+func (l *Logger) Info(msg string) {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	l.log("INFO", msg)
+}
+
+// Error logs an error message.
+func (l *Logger) Error(msg string, err error) {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	if err != nil {
+		l.log("ERROR", msg+" "+err.Error())
+	} else {
+		l.log("ERROR", msg)
+	}
+}
+
+// Debug logs a debug message.
+func (l *Logger) Debug(msg string) {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	l.log("DEBUG", msg)
+}
+
+func (l *Logger) log(level, msg string) {
+	prefix := l.prefix
+	if prefix != "" {
+		prefix = "[" + prefix + "] "
+	}
+
+	l.logger.SetPrefix(prefix + level + " ")
+	
+	var args []any
+	for k, v := range l.fields {
+		args = append(args, k, v)
+	}
+	
+	if len(args) > 0 {
+		l.logger.Printf(msg+" %+v", args...)
+	} else {
+		l.logger.Print(msg)
+	}
+}