Chapter 56. Integrating non-corosync nodes into a cluster: the pacemaker_remote service

Procedure

1. Configure the VirtualDomain resources.

2. Enter the following commands on every virtual machine to install pacemaker_remote packages, start the pcsd service and enable it to run on startup, and allow TCP port 3121 through the firewall.

   # yum install pacemaker-remote resource-agents pcs
   # systemctl start pcsd.service
   # systemctl enable pcsd.service
   # firewall-cmd --add-port 3121/tcp --permanent
   # firewall-cmd --add-port 2224/tcp --permanent
   # firewall-cmd --reload

3. Give each virtual machine a static network address and unique host name, which should be known to all nodes.

4. If you have not already done so, authenticate pcs to the node you will be integrating as a quest node.

   # pcs host auth nodename

5. Use the following command to convert an existing VirtualDomain resource into a guest node. This command must be run on a cluster node and not on the guest node which is being added. In addition to converting the resource, this command copies the /etc/pacemaker/authkey to the guest node and starts and enables the pacemaker_remote daemon on the guest node. The node name for the guest node, which you can define arbitrarily, can differ from the host name for the node.

   # pcs cluster node add-guest nodename resource_id [options]

6. After creating the VirtualDomain resource, you can treat the guest node just as you would treat any other node in the cluster. For example, you can create a resource and place a resource constraint on the resource to run on the guest node as in the following commands, which are run from a cluster node. You can include guest nodes in groups, which allows you to group a storage device, file system, and VM.

   # pcs resource create webserver apache configfile=/etc/httpd/conf/httpd.conf op monitor interval=30s
   # pcs constraint location webserver prefers nodename

Procedure

1. On the node that you will be configuring as a remote node, allow cluster-related services through the local firewall.

   # firewall-cmd --permanent --add-service=high-availability
   success
   # firewall-cmd --reload
   success

   Note

   If you are using iptables directly, or some other firewall solution besides firewalld, simply open the following ports: TCP ports 2224 and 3121.

2. Install the pacemaker_remote daemon on the remote node.

   # yum install -y pacemaker-remote resource-agents pcs

3. Start and enable pcsd on the remote node.

   # systemctl start pcsd.service
   # systemctl enable pcsd.service

4. If you have not already done so, authenticate pcs to the node you will be adding as a remote node.

   # pcs host auth remote1

5. Add the remote node resource to the cluster with the following command. This command also syncs all relevant configuration files to the new node, starts the node, and configures it to start pacemaker_remote on boot. This command must be run on a cluster node and not on the remote node which is being added.

   # pcs cluster node add-remote remote1

6. After adding the remote resource to the cluster, you can treat the remote node just as you would treat any other node in the cluster. For example, you can create a resource and place a resource constraint on the resource to run on the remote node as in the following commands, which are run from a cluster node.

   # pcs resource create webserver apache configfile=/etc/httpd/conf/httpd.conf op monitor interval=30s
   # pcs constraint location webserver prefers remote1

   Warning

   Never involve a remote node connection resource in a resource group, colocation constraint, or order constraint.

7. Configure fencing resources for the remote node. Remote nodes are fenced the same way as cluster nodes. Configure fencing resources for use with remote nodes the same as you would with cluster nodes. Note, however, that remote nodes can never initiate a fencing action. Only cluster nodes are capable of actually executing a fencing operation against another node.