Keycloak Load Balancer Configuration for High Availability

Keycloak works best in a high availability setup, and that means you need a load balancer configured with precision. Without it, session stickiness breaks, tokens fail, and logins stall under pressure. A proper Keycloak load balancer setup makes authentication resilient, scalable, and predictable even under sudden spikes.

Place the load balancer in front of all Keycloak nodes. Use TCP mode for HTTPS termination at the balancer, or pass TLS through if you need end-to-end encryption. Enable sticky sessions so that once a user hits a node, their session stays there. Keycloak stores session state in the database, but stickiness reduces database churn and improves response time.

For HAProxy, configure balance source or balance hdr(cookie) with persistence set to your session cookie. For Nginx, use ip_hash or sticky modules. In AWS, use Application Load Balancer with cookie stickiness enabled. In Kubernetes, consider Ingress with annotations for sticky sessions or an external load balancer service.

Set health checks to hit /auth/realms/master or another stable endpoint to ensure the node is alive. Avoid deep checks on admin endpoints—they are heavier. Configure failover so dead nodes are pulled quickly from rotation.

If you run multiple Keycloak instances, ensure they share the same database and have consistent configuration. Use DNS short TTL if your load balancer needs quick endpoint changes. Monitor latency, IOPS on the DB, and active session count—your load balancer is only as good as the slowest dependent system.

When scaling Keycloak horizontally, the load balancer is your control tower. Get it wrong, and authentication collapses under load. Get it right, and you gain uptime, speed, and confidence.

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