Keycloak is an open-source identity and access management solution that supports single sign-on, OAuth 2.0, OpenID Connect, and SAML. Out of the box it’s strong, but a single-node deployment is a single point of failure. For serious production workloads, you need a high availability architecture that eliminates downtime, scales horizontally, and survives outages.
A proper High Availability Keycloak setup runs multiple Keycloak instances behind a load balancer. Each node connects to a shared, highly available database. This ensures that requests keep flowing even if one node or database replica goes offline. Session data, user sessions, and tokens must replicate across nodes without delay. Sticky sessions can help, but in clustered setups, data should be stored centrally to avoid inconsistencies.
The load balancer—whether NGINX, HAProxy, or AWS ALB—routes traffic intelligently. Health checks detect unhealthy nodes and remove them from rotation. Horizontal scaling is simple: add nodes, update load balancer targets, and let Keycloak handle the rest. Keeping Keycloak stateless at the application layer ensures resilience; state lives in the database and cache layers.