We use a separate cache, work , which is replicated across all data centers. The work cache itself does not cache any real data.
It is used only for sending invalidation messages between cluster nodes and data centers. In other words, when data is updated, such as the user john , the Keycloak node sends the invalidation message to all other cluster nodes in the same data center and also to all other data centers. After receiving the invalidation notice, every node then invalidates the appropriate data from their local cache. There are Infinispan caches called sessions , clientSessions , offlineSessions , and offlineClientSessions , all of which usually need to be replicated across data centers. The caches must handle the HTTP requests from the end user and from the application.
As described above, sticky sessions can not be reliably used in this instance, but we still want to ensure that subsequent HTTP requests can see the latest data. For this reason, the data are usually replicated across data centers. Finally the loginFailures cache is used to track data about failed logins, such as how many times the user john entered a bad password. The details are described here. It is up to the admin whether this cache should be replicated across data centers.
To have an accurate count of login failures, the replication is needed. On the other hand, not replicating this data can save some performance. So if performance is more important than accurate counts of login failures, the replication can be avoided. For more detail about how caches can be configured see Tuning the JDG cache configuration. Keycloak uses multiple, separate clusters of Infinispan caches. Every Keycloak node is in the cluster with the other Keycloak nodes in same data center, but not with the Keycloak nodes in different data centers.
A Keycloak node does not communicate directly with the Keycloak nodes from different data centers. Keycloak nodes use external JDG actually Infinispan servers for communication across data centers.
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This is done using the Infinispan HotRod protocol. The Infinispan caches on the Keycloak side must be configured with the remoteStore to ensure that data are saved to the remote cache. Finally, the receiving JDG server notifies the Keycloak servers in its cluster through the Client Listeners, which are a feature of the HotRod protocol. Keycloak nodes on site2 then update their Infinispan caches and the particular user session is also visible on Keycloak nodes on site2. For this example, we describe using two data centers, site1 and site2.
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Each data center consists of 1 Infinispan server and 2 Keycloak servers. We will end up with 2 Infinispan servers and 4 Keycloak servers in total. Site1 consists of Infinispan server, jdg1 , and 2 Keycloak servers, node11 and node Site2 consists of Infinispan server, jdg2 , and 2 Keycloak servers, node21 and node Infinispan servers jdg1 and jdg2 are connected to each other through the RELAY2 protocol and backup based Infinispan caches in a similar way as described in the JDG documentation.
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Keycloak servers node11 and node12 form a cluster with each other, but they do not communicate directly with any server in site2. They communicate with the Infinispan server jdg1 using the HotRod protocol Remote cache. See Communication details for the details. The same details apply for node21 and node They cluster with each other and communicate only with jdg2 server using the HotRod protocol.
Our example setup assumes all that all 4 Keycloak servers talk to the same database. In production, it is recommended to use separate synchronously replicated databases across data centers as described in Database. Download Infinispan 9. Add the xsite channel, which will use tcp stack, under channels element:. Add a relay element to the end of the udp stack. We will configure it in a way that our site is site1 and the other site, where we will backup, is site2 :. Some Infinispan server releases require authorization before accessing protected caches over network.
If you get errors accessing this cache, you will need to set up authorization in clustered.
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For example:. It is currently required to have different configuration files for the JDG servers on both sites as the Infinispan subsystem does not support replacing site names with expressions. See this issue for more details.
Start server jdg2. There is a different multicast address, so the jdg1 and jdg2 servers are not directly clustered with each other; rather, they are just connected through the RELAY2 protocol, and the TCP JGroups stack is used for communication between them. The start up command looks like this:. Unzip Keycloak server distribution to a location you choose.
It will be referred to later as NODE Configure a shared database for KeycloakDS datasource. See Database for more details. In production you will likely need to have a separate database server in every data center and both database servers should be synchronously replicated to each other. In the example setup, we just use a single database and connect all 4 Keycloak servers to it. Add this module attribute under cache-container element of name keycloak :. Do the same for offlineSessions , clientSessions , offlineClientSessions , loginFailures , and actionTokens caches the only difference from sessions cache is that cache property value are different :.
Add outbound socket binding for the remote store into socket-binding-group element configuration:.
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The configuration of distributed cache authenticationSessions and other caches is left unchanged. The cluster nodes should be connected. After login, you should be able to see the same sessions in tab Sessions of particular user, client or realm on all 4 servers. After doing any change in Keycloak admin console eg. Check server. When you run the Keycloak server inside a data center, it is required that the database referenced in KeycloakDS datasource is already running and available in that data center.
It is also necessary that the Infinispan server referenced by the outbound-socket-binding , which is referenced from the Infinispan cache remote-store element, is already running. Otherwise the Keycloak server will fail to start. Every data center can have more database nodes if you want to support database failover and better reliability.
Refer to the documentation of your database and JDBC driver for the details how to set this up on the database side and how the KeycloakDS datasource on Keycloak side needs to be configured. Every datacenter can have more Infinispan servers running in the cluster.click here
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This is useful if you want some failover and better fault tolerance. The HotRod protocol used for communication between Infinispan servers and Keycloak servers has a feature that Infinispan servers will automatically send new topology to the Keycloak servers about the change in the Infinispan cluster, so the remote store on Keycloak side will know to which Infinispan servers it can connect. Read the Infinispan and WildFly documentation for more details. It is highly recommended that a master Infinispan server is running in every site before the Keycloak servers in any site are started.
As in our example, we started both jdg1 and jdg2 first, before all Keycloak servers. If you still need to run the Keycloak server and the backup site is offline, it is recommended to manually switch the backup site offline on the Infinispan servers on your site, as described in Bringing sites offline and online.
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