✨ Enhance observability and error handling in NATS integration. Introduce comprehensive OpenTelemetry support with environment-based sampling and semantic attributes for tracing and metrics. Implement an advisory dead-letter queue (DLQ) handler for managing message delivery failures. Update NATS consumer to utilize structured logging and improve error handling strategies. Refactor configuration files for OpenTelemetry collector in both development and production environments, ensuring robust telemetry integration. Enhance documentation to reflect new features and best practices for observability.

internal/infra/nats/consumer_core.go

@@ -14,7 +14,7 @@ import (
 func (c *Consumer) startCore(ctx context.Context) error {
 	queueGroup := c.cfg.Subscription.QueueGroup
 	if queueGroup == "" {
-		queueGroup = c.consumerName
+		queueGroup = c.config.consumerName
 	}
 
 	handler := func(msg *nats.Msg) {
@@ -28,16 +28,16 @@ func (c *Consumer) startCore(ctx context.Context) error {
 		}
 	}
 
-	sub, err := c.conn.QueueSubscribe(c.subject, queueGroup, handler)
+	sub, err := c.conn.QueueSubscribe(c.config.subject, queueGroup, handler)
 	if err != nil {
-		return fmt.Errorf("failed to subscribe to %s: %w", c.subject, err)
+		return fmt.Errorf("failed to subscribe to %s: %w", c.config.subject, err)
 	}
 	if err := c.conn.Flush(); err != nil {
 		return fmt.Errorf("failed to flush NATS connection: %w", err)
 	}
 
 	c.logger.Info("Started core NATS subscription",
-		zap.String("subject", c.subject),
+		zap.String("subject", c.config.subject),
 		zap.String("queue_group", queueGroup),
 	)