1.7. About Domain Controller Discovery and Failover
When setting up a managed domain, each host controller must be configured with information needed to contact the domain controller. In JBoss EAP 6, each host controller can be configured with multiple options for finding the domain controller. Host controllers iterate through the list of options until one succeeds.
This allows host controllers to be pre-configured with contact information for a backup domain controller. A backup host controller can be promoted to master if there is a problem with the primary domain controller, allowing host controllers to automatically fail over to the new master once it’s been promoted.
The following is an example of how to configure a host controller with multiple options for finding the domain controller.
Example 1.1. Host controller configured with multiple domain controller options
<domain-controller>
<remote security-realm="ManagementRealm">
<discovery-options>
<static-discovery name="primary" host="172.16.81.100" port="9999"/>
<static-discovery name="backup" host="172.16.81.101" port="9999"/>
</discovery-options>
</remote>
</domain-controller>
A static discovery option includes the following mandatory attributes:
- name
- The name for this domain controller discovery option
- host
- The remote domain controller's host name.
- port
- The remote domain controller's port.
In the example above, the first discovery option is the one expected to succeed. The second can be used in failover situations.
If a problem arises with the primary domain controller, a host controller that was started with the
--backup option can be promoted to act as the domain controller.
Note
Starting a host controller with the
--backup option will cause that controller to maintain a local copy of the domain configuration. This configuration will be used if the host controller is reconfigured to act as the domain controller.
Procedure 1.1. Promoting a host controller to be the domain controller
- Ensure the original domain controller has, or is, stopped.
- Use the Management CLI to connect to the host controller that is to become the new domain controller.
- Execute the following command to configure the host controller to act as the new domain controller.
/host=HOST_NAME:write-local-domain-controller - Execute the following command to reload the host controller.
reload --host=HOST_NAME
The host controller chosen in step 2 will now act as the domain controller.
