CLI Testing

1. Check Replication Status

• On the Master:
  • redis-cli -h <master_host> -p <master_port> INFO REPLICATION
  • Look for connected_slaves. It should list all connected replicas with their IP addresses and ports.
• On the Replica:
  • redis-cli -h <replica_host> -p <replica_port> INFO REPLICATION
  • Verify role:slave, master_host, master_port, and that slave_read_only is set to 1.

2. Monitor Replication Lag

• On the Master:
  • redis-cli -h <master_host> -p <master_port> INFO REPLICATION
  • Note the master_repl_offset.
• On the Replica:
  • redis-cli -h <replica_host> -p <replica_port> INFO REPLICATION
  • Note the slave_repl_offset.
  • Calculate the difference between master_repl_offset and slave_repl_offset. A small difference indicates low lag.

3. Test Data Consistency

• Set a Key on the Master:
  • redis-cli -h <master_host> -p <master_port> SET mykey "value"
• Get the Key on the Replica:
  • redis-cli -h <replica_host> -p <replica_port> GET mykey
  • Verify that the value retrieved from the replica matches the value set on the master.

4. Force a Resync (for testing)

• On the Replica:
  • redis-cli -h <replica_host> -p <replica_port> SLAVEOF NO ONE
  • redis-cli -h <replica_host> -p <replica_port> SLAVEOF <master_host> <master_port>

Key Considerations:

• Frequency: Regularly run these checks to monitor replication health.
• Scripting: Create scripts to automate these checks and generate reports.
• Alerting: Set up alerts based on replication lag thresholds.