Ensuring Middleware Reliability: A Practical Guide for Redis, RabbitMQ, and Kafka

Scenario

You are an SRE on call. Your team's e-commerce platform experiences order processing delays during flash sales. The architecture uses Redis for session caching, RabbitMQ for order queueing, and Kafka for event streaming. After a recent scaling event, latency spikes occur.

Symptoms

• Redis: Increased latency > 100ms, CPU high, evictions.
• RabbitMQ: Queue depth growing, consumers idle, disk alarm.
• Kafka: Consumer lag increasing, broker CPU high, replication underreplicated partitions.

Diagnosis

Redis

• redis-cli info stats check evicted_keys.
• redis-cli slowlog get for slow commands.
• redis-cli client list for connections.
• Use memory doctor if OOM.

RabbitMQ

• rabbitmqctl list_queues name messages consumers memory.
• Check disk and memory alarms via rabbitmqctl status.
• Enable trace logs if needed.

Kafka

• kafka-consumer-groups --bootstrap-server <server> --describe --group <group> for lag.
• kafka-topics --describe --under-replicated-partitions.
• Check broker logs and JMX metrics.

Commands (with safety notes)

Redis

• To clear slow commands, consider scaling read replicas or optimizing data structures. Use CLIENT KILL cautiously.

RabbitMQ

• To unbind queues temporarily: rabbitmqctl set_policy to limit queue length or rabbitmqadmin delete queue with caution. Use rabbitmqctl set_disk_free_limit to adjust alarms.

Kafka

• To throttle consumers: increase partitions or use consumer group rebalancing. For hot partitions, kafka-reassign-partitions.sh. Never delete topics without backup.

Risk Controls

• Always snapshot Redis RDB/AOF before changes.
• For RabbitMQ, backup definitions with rabbitmqadmin export.
• For Kafka, back up offsets and topic configs. Use racks awareness.

Rollback Procedures

Redis

• Restore from RDB or AOF backup. Ensure no pending writes lost.

RabbitMQ

• Re-import definitions, purge queues if needed.

Kafka

• Reset consumer group offsets via kafka-consumer-groups --reset-offsets. For data loss, replay from last committed.

Verification

• Redis: redis-benchmark test latency. Monitor evictions and hits/misses.
• RabbitMQ: Publish test messages, verify consumption rate.
• Kafka: Produce and consume test records, check lag reduced.

When to submit an OpsGlobal ticket

• If root cause unclear after checks.
• If data loss occurred or risk of data loss.
• If Kubernetes pod restarts or persistent volume issues persist.
• If you need help with fine-tuning configurations or security hardening.