Resource Meta-Attributes for Guest Nodes

When configuring a virtual machine as a guest node, the virtual machine is created using one of the usual resource agents for that purpose (for example, ocf:heartbeat:VirtualDomain or ocf:heartbeat:Xen), with additional metadata parameters.

No restrictions are enforced on what agents may be used to create a guest node, but obviously the agent must create a distinct environment capable of running the pacemaker_remote daemon and cluster resources. An additional requirement is that fencing the host running the guest node resource must be sufficient for ensuring the guest node is stopped. This means, for example, that not all hypervisors supported by VirtualDomain may be used to create guest nodes; if the guest can survive the hypervisor being fenced, it may not be used as a guest node.

Below are the metadata options available to enable a resource as a guest node and define its connection parameters.

Connection Resources for Remote Nodes

A remote node is defined by a connection resource. That connection resource has instance attributes that define where the remote node is located on the network and how to communicate with it.

Descriptions of these instance attributes can be retrieved using the following pcs command:

# pcs resource describe remote
ocf:pacemaker:remote - remote resource agent

Resource options:
  server: Server location to connect to. This can be an ip address or hostname.
  port: tcp port to connect to.
  reconnect_interval: Interval in seconds at which Pacemaker will attempt to
                      reconnect to a remote node after an active connection to
                      the remote node has been severed. When this value is
                      nonzero, Pacemaker will retry the connection
                      indefinitely, at the specified interval.

When defining a remote node's connection resource, it is common and recommended to name the connection resource the same as the remote node's hostname. By default, if no server option is provided, the cluster will attempt to contact the remote node using the resource name as the hostname.

Example defining a remote node with the hostname remote1:

# pcs resource create remote1 remote

Example defining a remote node to connect to a specific IP address and port:

# pcs resource create remote1 remote server=192.168.122.200 port=8938

Environment Variables for Daemon Start-up

Authentication and encryption of the connection between cluster nodes and nodes running pacemaker_remote is achieved using with TLS-PSK encryption/authentication over TCP (port 3121 by default). This means that both the cluster node and remote node must share the same private key. By default, this key is placed at /etc/pacemaker/authkey on each node.

You can change the default port and/or key location for Pacemaker and pacemaker_remote via environment variables. How these variables are set varies by OS, but usually they are set in the /etc/sysconfig/pacemaker or /etc/default/pacemaker file.

#==#==# Pacemaker Remote
# Use a custom directory for finding the authkey.
PCMK_authkey_location=/etc/pacemaker/authkey
#
# Specify a custom port for Pacemaker Remote connections
PCMK_remote_port=3121

Removing Remote Nodes and Guest Nodes

If the resource creating a guest node, or the ocf:pacemaker:remote resource creating a connection to a remote node, is removed from the configuration, the affected node will continue to show up in output as an offline node.

If you want to get rid of that output, run (replacing $NODE_NAME appropriately):

# crm_node --force --remove $NODE_NAME