feat: authsession service

authsession/internal/logging/logger.go

@@ -0,0 +1,82 @@
+// Package logging configures the authsession structured logger and provides
+// context-aware helpers for attaching OpenTelemetry trace identifiers.
+package logging
+
+import (
+	"context"
+	"strings"
+
+	"go.opentelemetry.io/otel/trace"
+	"go.uber.org/zap"
+	"go.uber.org/zap/zapcore"
+)
+
+// New constructs the process-wide JSON logger from level.
+func New(level string) (*zap.Logger, error) {
+	atomicLevel := zap.NewAtomicLevel()
+	if err := atomicLevel.UnmarshalText([]byte(strings.TrimSpace(level))); err != nil {
+		return nil, err
+	}
+
+	zapCfg := zap.NewProductionConfig()
+	zapCfg.Level = atomicLevel
+	zapCfg.Sampling = nil
+	zapCfg.Encoding = "json"
+	zapCfg.EncoderConfig.TimeKey = "timestamp"
+	zapCfg.EncoderConfig.EncodeTime = zapcore.ISO8601TimeEncoder
+	zapCfg.OutputPaths = []string{"stdout"}
+	zapCfg.ErrorOutputPaths = []string{"stderr"}
+
+	return zapCfg.Build()
+}
+
+// TraceFieldsFromContext returns zap fields for the active OpenTelemetry span
+// when ctx carries a valid span context.
+func TraceFieldsFromContext(ctx context.Context) []zap.Field {
+	if ctx == nil {
+		return nil
+	}
+
+	spanContext := trace.SpanContextFromContext(ctx)
+	if !spanContext.IsValid() {
+		return nil
+	}
+
+	return []zap.Field{
+		zap.String("otel_trace_id", spanContext.TraceID().String()),
+		zap.String("otel_span_id", spanContext.SpanID().String()),
+	}
+}
+
+// Sync flushes logger and ignores the benign stdout or stderr sync errors
+// commonly returned by containerized or redirected process outputs.
+func Sync(logger *zap.Logger) error {
+	if logger == nil {
+		return nil
+	}
+
+	err := logger.Sync()
+	if err == nil || isIgnorableSyncError(err) {
+		return nil
+	}
+
+	return err
+}
+
+func isIgnorableSyncError(err error) bool {
+	if err == nil {
+		return false
+	}
+
+	message := strings.ToLower(err.Error())
+	switch {
+	case strings.Contains(message, "invalid argument"):
+		return true
+	case strings.Contains(message, "bad file descriptor"):
+		return true
+	case strings.Contains(message, "inappropriate ioctl for device"):
+		return true
+	default:
+		return false
+	}
+}