187 lines
9.3 KiB
XML
Executable file
187 lines
9.3 KiB
XML
Executable file
<chapter id="clustering">
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<title>Clustering</title>
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<para>To improve availability and scalability Keycloak can be deployed in a cluster.</para>
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<para>It's fairly straightforward to configure a Keycloak cluster, the steps required are:
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<itemizedlist>
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<listitem>
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<para>
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Configure a shared database
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</para>
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</listitem>
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<listitem>
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<para>
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Configure Infinispan
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</para>
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</listitem>
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<listitem>
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<para>
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Enable realm and user cache invalidation
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</para>
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</listitem>
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<listitem>
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<para>
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Enable distributed user sessions
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</para>
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</listitem>
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<listitem>
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<para>
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Start in HA mode
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</para>
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</listitem>
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</itemizedlist>
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</para>
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<section>
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<title>Configure a shared database</title>
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<para>
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Keycloak doesn't replicate realms and users, but instead relies on all nodes using the same
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database. This can be a relational database or Mongo. To make sure your database doesn't become a single
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point of failure you may also want to deploy your database to a cluster.
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</para>
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</section>
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<section>
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<title id="cluster-configure-infinispan">Configure Infinispan</title>
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<para>
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Keycloak uses <ulink url="http://www.infinispan.org/">Infinispan</ulink> caches to share information between nodes.
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</para>
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<para>
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For realm and users Keycloak uses a invalidation cache. An invalidation cache doesn't share any data, but simply
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removes stale data from remote caches and makes sure all nodes re-load data from the database when it is changed. This reduces network traffic, as well as preventing sensitive data (such as
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realm keys and password hashes) from being sent between the nodes.
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</para>
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<para>
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User sessions and login failures supports either distributed caches or fully replicated caches. We recommend using a distributed
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cache. A distributed
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cache splits user sessions into segments where each node holds one or more segment. It is possible
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to replicate each segment to multiple nodes, but this is not strictly necessary since the failure of a node
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will only result in users having to log in again. If you need to prevent node failures from requiring users to
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log in again, set the <literal>owners</literal> attribute to 2 or more for the <literal>sessions</literal> cache
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of <literal>infinispan/Keycloak</literal> container as described below.
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</para>
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<para>
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The infinispan container is set by default in <literal>standalone/configuration/keycloak-server.json</literal>:
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<programlisting>
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"connectionsInfinispan": {
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"default" : {
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"cacheContainer" : "java:jboss/infinispan/Keycloak"
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}
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}
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</programlisting>
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</para>
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<para>As you can see in this file, the realmCache, userCache and userSession providers are configured to use infinispan by default, which applies for both cluster and non-cluster environment.</para>
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<para>
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For non-cluster configuration (server executed with <literal>standalone.xml</literal> ) is the infinispan container <literal>infinispan/Keycloak</literal> just uses local infinispan caches for realms, users and userSessions.
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</para>
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<para>
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For cluster configuration, you can edit the configuration of <literal>infinispan/Keycloak</literal> container in <literal>standalone/configuration/standalone-ha.xml</literal> (or <literal>standalone-keycloak-ha.xml</literal>
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if you are using overlay or demo distribution) .
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</para>
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</section>
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<section>
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<title>Start in HA mode</title>
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<para>
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To start the server in HA mode, start it with:
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<programlisting># bin/standalone --server-config=standalone-ha.xml</programlisting>
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or if you are using overlay or demo distribution with:
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<programlisting># bin/standalone --server-config=standalone-keycloak-ha.xml</programlisting>
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</para>
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<para>
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Alternatively you can copy <literal>standalone/config/standalone-ha.xml</literal> to <literal>standalone/config/standalone.xml</literal>
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to make it the default server config.
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</para>
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</section>
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<section>
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<title>Enabling cluster security</title>
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<para>
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By default there's nothing to prevent unauthorized nodes from joining the cluster and sending potentially malicious
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messages to the cluster. However, as there's no sensitive data sent there's not much that can be achieved.
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For realms and users all that can be done is to send invalidation messages to make nodes load data from the
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database more frequently. For user sessions it would be possible to modify existing user sessions, but creating
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new sessions would have no affect as they would not be linked to any access tokens. There's not too much that
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can be achieved by modifying user sessions. For example it would be possible to prevent sessions from expiring,
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by changing the creation time. However, it would for example have no effect adding additional permissions to the
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sessions as these are rechecked against the user and application when the token is created or refreshed.
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</para>
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<para>
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In either case your cluster nodes should be in a private network, with a firewall protecting them from outside
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attacks. Ideally isolated from workstations and laptops. You can also enable encryption of cluster messages,
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this could for example be useful if you can't isolate cluster nodes from workstations and laptops on your private
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network. However, encryption will obviously come at a cost of reduced performance.
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</para>
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<para>
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To enable encryption of cluster messages you first have to create a shared keystore (change the key and store passwords!):
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<programlisting>
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<![CDATA[
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# keytool -genseckey -alias keycloak -keypass <PASSWORD> -storepass <PASSWORD> \
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-keyalg Blowfish -keysize 56 -keystore defaultStore.keystore -storetype JCEKS
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]]>
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</programlisting>
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</para>
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<para>
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Copy this keystore to all nodes (for example to standalone/configuration). Then configure JGroups to encrypt all
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messages by adding the <literal>ENCRYPT</literal> protocol to the JGroups sub-system (this should be added after
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the <literal>pbcast.GMS</literal> protocol):
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<programlisting>
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<![CDATA[
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<subsystem xmlns="urn:jboss:domain:jgroups:2.0" default-stack="udp">
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<stack name="udp">
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...
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<protocol type="pbcast.GMS"/>
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<protocol type="ENCRYPT">
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<property name="key_store_name">
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${jboss.server.config.dir}/defaultStore.keystore
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</property>
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<property name="key_password">PASSWORD</property>
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<property name="store_password">PASSWORD</property>
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<property name="alias">keycloak</property>
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</protocol>
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...
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</stack>
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<stack name="tcp">
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...
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<protocol type="pbcast.GMS"/>
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<protocol type="ENCRYPT">
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<property name="key_store_name">
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${jboss.server.config.dir}/defaultStore.keystore
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</property>
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<property name="key_password">PASSWORD</property>
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<property name="store_password">PASSWORD</property>
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<property name="alias">keycloak</property>
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</protocol>
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...
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</stack>
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...
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</subsystem>
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]]>
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</programlisting>
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See the <ulink url="http://www.jgroups.org/manual/index.html#ENCRYPT">JGroups manual</ulink> for more details.
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</para>
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</section>
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<section>
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<title>Troubleshooting</title>
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<para>
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Note that when you run cluster, you should see message similar to this in the log of both cluster nodes:
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<programlisting>
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<![CDATA[
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INFO [org.infinispan.remoting.transport.jgroups.JGroupsTransport] (Incoming-10,shared=udp)
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ISPN000094: Received new cluster view: [node1/keycloak|1] (2) [node1/keycloak, node2/keycloak]
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]]>
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</programlisting>
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If you see just one node mentioned, it's possible that your cluster hosts are not joined together.
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</para>
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<para>
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Usually it's best practice to have your cluster nodes on private network without firewall for communication among them.
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Firewall could be enabled just on public access point to your network instead. If for some reason you still need to have firewall
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enabled on cluster nodes, you will need to open some ports. Default values are UDP port 55200 and multicast port 45688
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with multicast address 230.0.0.4. Note that you may need more ports opened if you want to enable additional features like diagnostics for your JGroups stack.
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Keycloak delegates most of the clustering work to Infinispan/JGroups, so consult EAP or JGroups documentation for more info.
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</para>
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</section>
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</chapter>
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