Redis HA

A highly available Redis cluster using:

• Redis + Sentinel (colocated) on each node (ports 6379 / 26379)
• HAProxy for client connections, routing writes to the node reporting role:master

Architecture

• Redis-1 (Primary): Current master (may change after failover)
• Redis-2+ (Replicas): Streaming replicas that promote on primary loss
• Redis HA (Edge): HAProxy entry point — use this for all client connections

Minimum 3 Redis nodes: Sentinel requires a majority to authorize failover, so a 2-node cluster split-brains on a symmetric partition. 3 nodes (quorum 2) tolerate 1 node loss.

Connecting

Use the REDIS_URL or REDIS_PUBLIC_URL from the "Redis HA" (HAProxy) service. Do not connect directly to individual Redis nodes.

Scaling

• Replicas: scale from 2-5 using the cluster overview
• Sentinel quorum is ceil(nodes/2) - defaults are sized for 3 total nodes