2. Configuration Explained

The walk-through examples use some of these options, but don’t explain exactly what they mean or do. This section is meant to be the go-to resource for all the options available for configuring Pacemaker Remote.

2.1. 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 meta-attributes.

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 meta-attributes available to enable a resource as a guest node and define its connection parameters.

Meta-attributes for configuring VM resources as guest nodes
Option Default Description
remote-node none The node name of the guest node this resource defines. This both enables the resource as a guest node and defines the unique name used to identify the guest node. If no other parameters are set, this value will also be assumed as the hostname to use when connecting to pacemaker_remote on the VM. This value must not overlap with any resource or node IDs.
remote-port 3121 The port on the virtual machine that the cluster will use to connect to pacemaker_remote.
remote-addr ‘value of’ remote-node The IP address or hostname to use when connecting to pacemaker_remote on the VM.
remote-connect-timeout 60s How long before a pending guest connection will time out.

2.2. 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 (IP address or resolvable host name)
  port: TCP port at which to contact Pacemaker Remote executor
  reconnect_interval: If this is a positive time interval, the cluster will attempt to
                      reconnect to a remote node after an active connection has been
                      lost at this interval. Otherwise, the cluster will attempt to
                      reconnect immediately (after any fencing needed).

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.

2.3. 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_remoted 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 the contents of this file as the authorization key to use with Pacemaker
# Remote connections. This file must be readable by Pacemaker daemons (that is,
# it must allow read permissions to either the hacluster user or the haclient
# group), and its contents must be identical on all nodes. The default is
# "/etc/pacemaker/authkey".
# PCMK_authkey_location=/etc/pacemaker/authkey

# If the Pacemaker Remote service is run on the local node, it will listen
# for connections on this address. The value may be a resolvable hostname or an
# IPv4 or IPv6 numeric address. When resolving names or using the default
# wildcard address (i.e. listen on all available addresses), IPv6 will be
# preferred if available. When listening on an IPv6 address, IPv4 clients will
# be supported (via IPv4-mapped IPv6 addresses).
# PCMK_remote_address="192.0.2.1"

# Use this TCP port number when connecting to a Pacemaker Remote node. This
# value must be the same on all nodes. The default is "3121".
# PCMK_remote_port=3121

# Use these GnuTLS cipher priorities for TLS connections. See:
#
#   https://gnutls.org/manual/html_node/Priority-Strings.html
#
# Pacemaker will append ":+ANON-DH" for remote CIB access (when enabled) and
# ":+DHE-PSK:+PSK" for Pacemaker Remote connections, as they are required for
# the respective functionality.
# PCMK_tls_priorities="NORMAL"

# Set bounds on the bit length of the prime number generated for Diffie-Hellman
# parameters needed by TLS connections. The default is not to set any bounds.
#
# If these values are specified, the server (Pacemaker Remote daemon, or CIB
# manager configured to accept remote clients) will use these values to provide
# a floor and/or ceiling for the value recommended by the GnuTLS library. The
# library will only accept a limited number of specific values, which vary by
# library version, so setting these is recommended only when required for
# compatibility with specific client versions.
#
# If PCMK_dh_min_bits is specified, the client (connecting cluster node or
# remote CIB command) will require that the server use a prime of at least this
# size. This is only recommended when the value must be lowered in order for
# the client's GnuTLS library to accept a connection to an older server.
# The client side does not use PCMK_dh_max_bits.
#
# PCMK_dh_min_bits=1024
# PCMK_dh_max_bits=2048

2.4. 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

Warning

Be absolutely sure that there are no references to the node’s resource in the configuration before running the above command.