feat: notification service

notification/internal/logging/logger.go

@@ -0,0 +1,112 @@
+// Package logging configures the Notification Service process logger and
+// provides context-aware helpers for trace fields.
+package logging
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+	"os"
+	"strings"
+
+	"galaxy/notification/internal/api/intentstream"
+
+	"go.opentelemetry.io/otel/trace"
+)
+
+// New constructs the process-wide JSON logger from level.
+func New(level string) (*slog.Logger, error) {
+	var slogLevel slog.Level
+	if err := slogLevel.UnmarshalText([]byte(strings.TrimSpace(level))); err != nil {
+		return nil, fmt.Errorf("build logger: %w", err)
+	}
+
+	return slog.New(slog.NewJSONHandler(os.Stdout, &slog.HandlerOptions{
+		Level: slogLevel,
+	})), nil
+}
+
+// TraceAttrsFromContext returns slog key-value pairs for the active
+// OpenTelemetry span when ctx carries a valid span context.
+func TraceAttrsFromContext(ctx context.Context) []any {
+	if ctx == nil {
+		return nil
+	}
+
+	spanContext := trace.SpanContextFromContext(ctx)
+	if !spanContext.IsValid() {
+		return nil
+	}
+
+	return []any{
+		"otel_trace_id", spanContext.TraceID().String(),
+		"otel_span_id", spanContext.SpanID().String(),
+	}
+}
+
+// NotificationAttrs returns structured notification-identifying log fields.
+func NotificationAttrs(
+	notificationID string,
+	notificationType intentstream.NotificationType,
+	producer intentstream.Producer,
+	audienceKind intentstream.AudienceKind,
+	idempotencyKey string,
+	requestID string,
+	traceID string,
+) []any {
+	attrs := []any{
+		"notification_id", notificationID,
+		"notification_type", string(notificationType),
+		"producer", string(producer),
+		"audience_kind", string(audienceKind),
+		"idempotency_key", idempotencyKey,
+	}
+	if strings.TrimSpace(requestID) != "" {
+		attrs = append(attrs, "request_id", requestID)
+	}
+	if strings.TrimSpace(traceID) != "" {
+		attrs = append(attrs, "trace_id", traceID)
+	}
+
+	return attrs
+}
+
+// IntentAttrs returns structured intent-identifying log fields when a durable
+// notification record does not yet exist.
+func IntentAttrs(intent intentstream.Intent) []any {
+	attrs := []any{
+		"notification_type", string(intent.NotificationType),
+		"producer", string(intent.Producer),
+		"audience_kind", string(intent.AudienceKind),
+		"idempotency_key", intent.IdempotencyKey,
+	}
+	if strings.TrimSpace(intent.RequestID) != "" {
+		attrs = append(attrs, "request_id", intent.RequestID)
+	}
+	if strings.TrimSpace(intent.TraceID) != "" {
+		attrs = append(attrs, "trace_id", intent.TraceID)
+	}
+
+	return attrs
+}
+
+// RouteAttrs returns structured route-identifying log fields.
+func RouteAttrs(
+	notificationID string,
+	notificationType intentstream.NotificationType,
+	producer intentstream.Producer,
+	audienceKind intentstream.AudienceKind,
+	idempotencyKey string,
+	requestID string,
+	traceID string,
+	routeID string,
+	channel intentstream.Channel,
+) []any {
+	attrs := NotificationAttrs(notificationID, notificationType, producer, audienceKind, idempotencyKey, requestID, traceID)
+	attrs = append(attrs,
+		"route_id", routeID,
+		"channel", string(channel),
+	)
+
+	return attrs
+}