Guidance on multi-site setup #42527

richard-sistern · 2025-09-10T15:36:09Z

richard-sistern
Sep 10, 2025

Hi,

Pretty new to Keycloak/Infinispan and looking for some advice on a multi-site setup. Have been through a lot of documentation and GitHub issues/discussions on this but my understanding may be a little lacking!

Proposed setup

Keycloak 26.3.1 installed via the operator
Two Kubernetes (Azure AKS) clusters running in separate regions (West & North Europe)
Currently no network link between the clusters, one can be created if required. The [round trip latency is ~18](https://learn.microsoft.com/en-us/azure/networking/azure-network-latency?tabs=Europe%2CWesternEurope).
Keycloak in both clusters connects to the same external PostgreSQL (Azure Flexible Server) database located in West Europe. There will be an async read replica in North Europe
A Cloudflare load balancer (session affinity configured) directs traffic to the AKS clusters.

I was initially hoping to take advantage of persistent sessions and simply treat this as a single site. However the docs indicate such an approach wont work:

Why do we need external Infinispan in a multi-site setup with persistent user sessions

In this case external Infinispan is not used for storing sessions, however, we still need it for communication between two Keycloak sites, for example, for invalidation messages, for synchronization of background tasks and also for storing some objects, usually short-lived, like authentication sessions, login failures or action tokens.

Source: [Storing sessions in Keycloak 26 - Keycloak](https://www.keycloak.org/2024/12/storing-sessions-in-kc26)

Am I correct in thinking my only options are:

Use the current setup in an active/passive way with traffic managed by the CloudFlare load balancer
Deploy Infinispan into the cluster and connect the two with Gossip Router as described [Building blocks multi-site deployments - Keycloak](https://www.keycloak.org/high-availability/bblocks-multi-site). This will add management overhead I guess, unsure how much though. There is reference to latency being an issue when stretching Infinispan, I'm unable to find anything on where the actual upper limit is. Unsure if this is even an option at present?

Any thoughts, ideas, clarifications etc most welcome :)

Thanks

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Guidance on multi-site setup #42527

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richard-sistern Sep 10, 2025

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richard-sistern
Sep 10, 2025