keycloak-scim/topics/clustering/load-balancer.adoc

=== Setting Up a Load Balancer

This section only covers configuring the built in load balancer that is discussed in the
<<fake/../../operating-mode/domain.adoc#_clustered-domain-example, Clustered Domain Example>>.
The link:{{book.appserver.loadbalancer.link}}[the load balancer] chapter of the {{book.appserver.loadbalancer.name}}
has information on using some other software based load balancers that may help you.

The <<fake/../../operating-mode/domain.adoc#_clustered-domain-example, Clustered Domain Example>> is only designed to run
on one machine.  To bring up a slave on another host, you'll need to

. Edit the _domain.xml_ file to point to your new host slave
. Copy the server distribution.  You don't need the _domain.xml_, _host.xml_, or _host-master.xml_ files.  Nor do you need
  the _standalone/_ directory.
. Edit the _host-slave.xml_ file to change the bind addresses used or override them on the command line

==== Register a New Host With Load Balancer

Let's look first at registering the new host slave with the load balancer configuration in _domain.xml_.  Open this
file and go to the undertow configuration in the `load-balancer` profile.  Add a new `host` definition called
`remote-host3` within the `reverse-proxy` XML block.

.domain.xml reverse-proxy config
[source,xml]
----
<subsystem xmlns="urn:jboss:domain:undertow:3.0">
  ...
  <handlers>
      <reverse-proxy name="lb-handler">
         <host name="host1" outbound-socket-binding="remote-host1" scheme="ajp" path="/" instance-id="myroute1"/>
         <host name="host2" outbound-socket-binding="remote-host2" scheme="ajp" path="/" instance-id="myroute2"/>
         <host name="remote-host3" outbound-socket-binding="remote-host3" scheme="ajp" path="/" instance-id="myroute3"/>
      </reverse-proxy>
  </handlers>
  ...
</subsystem>
----

The `output-socket-binding` is a logical name pointing to a `socket-binding` configured later in the _domain.xml_ file.
the `instance-id` attribute must also be unique to the new host as this value is used by a cookie to enable sticky
sessions when load balancing.

Next go down to the `load-balancer-sockets` `socket-binding-group` and add the `outbound-socket-binding` for `remote-host3`.  This new
binding needs to point to the host and port of the new host.

.domain.xml outbound-socket-binding
[source,xml]
----
<socket-binding-group name="load-balancer-sockets" default-interface="public">
    ...
    <outbound-socket-binding name="remote-host1">
        <remote-destination host="localhost" port="8159"/>
    </outbound-socket-binding>
    <outbound-socket-binding name="remote-host2">
        <remote-destination host="localhost" port="8259"/>
    </outbound-socket-binding>
    <outbound-socket-binding name="remote-host3">
        <remote-destination host="192.168.0.5" port="8259"/>
    </outbound-socket-binding>
</socket-binding-group>
----

==== Master Bind Addresses

Next thing you'll have to do is to change the `public` and `management` bind addresses for the master host.  Either
edit the _domain.xml_ file as discussed in the <<fake/../../network/bind-address.adoc#_bind-address, Bind Addresses>> chapter
or specify these bind addresses on the command line as follows:

[source]
----
$ domain.sh --host-config=host-master.xml -Djboss.bind.address=192.168.0.2 -Djboss.bind.address.management=192.168.0.2
----

==== Host Slave Bind Addresses

Next you'll have to change the `public`, `management`, and domain controller bind addresses (`jboss.domain.master-address`).  Either edit the
_host-slave.xml_ file or specify them on the command line as follows:

[source]
----
$ domain.sh --host-config=host-slave.xml
     -Djboss.bind.address=192.168.0.5
      -Djboss.bind.address.management=192.168.0.5
       -Djboss.domain.master.address=192.168.0.2
----

The values of `jboss.bind.address` and `jboss.bind.addres.management` pertain to the host slave's IP address.
The value of `jboss.domain.master.address` need to be the IP address of the domain controller which is the management address
of the master host.