11.11. Configuring a high availability cluster with SBD node fencing by using the ha_cluster_node_options variable

Procedure

1. Store your sensitive variables in an encrypted file:

   1. Create the vault:

      $ ansible-vault create ~/vault.yml
      New Vault password: <vault_password>
      Confirm New Vault password: <vault_password>

   2. After the ansible-vault create command opens an editor, enter the sensitive data in the <key>: <value> format:

      cluster_password: <cluster_password>

   3. Save the changes, and close the editor. Ansible encrypts the data in the vault.

2. Create a playbook file, for example, ~/playbook.yml, with the following content:

   ---
   - name: Create a high availability cluster
     hosts: node1 node2
     vars_files:
       - ~/vault.yml
     tasks:
       - name: Configure a cluster with SBD fencing
         ansible.builtin.include_role:
           name: redhat.rhel_system_roles.ha_cluster
         vars:
           my_sbd_devices:
             # This variable is indirectly used by various variables of the ha_cluster RHEL system role.
             # Its purpose is to define SBD devices once so they do not need
             # to be repeated several times in the role variables.
             - /dev/disk/by-id/000001
             - /dev/disk/by-id/000002
             - /dev/disk/by-id/000003
           ha_cluster_cluster_name: my-new-cluster
           ha_cluster_hacluster_password: "{{ cluster_password }}"
           ha_cluster_manage_firewall: true
           ha_cluster_manage_selinux: true
           ha_cluster_sbd_enabled: true
           ha_cluster_sbd_options:
             - name: delay-start
               value: 'no'
             - name: startmode
               value: always
             - name: timeout-action
               value: 'flush,reboot'
             - name: watchdog-timeout
               value: 30
           ha_cluster_node_options:
             - node_name: node1
               sbd_watchdog_modules:
                 - iTCO_wdt
               sbd_watchdog_modules_blocklist:
                 - ipmi_watchdog
               sbd_watchdog: /dev/watchdog1
               sbd_devices: "{{ my_sbd_devices }}"
             - node_name: node2
               sbd_watchdog_modules:
                 - iTCO_wdt
               sbd_watchdog_modules_blocklist:
                 - ipmi_watchdog
               sbd_watchdog: /dev/watchdog1
               sbd_devices: "{{ my_sbd_devices }}"
           # Best practice for setting SBD timeouts:
           # watchdog-timeout * 2 = msgwait-timeout (set automatically)
           # msgwait-timeout * 1.2 = stonith-timeout
           ha_cluster_cluster_properties:
             - attrs:
                 - name: stonith-timeout
                   value: 72
           ha_cluster_resource_primitives:
             - id: fence_sbd
               agent: 'stonith:fence_sbd'
               instance_attrs:
                 - attrs:
                     - name: devices
                       value: "{{ my_sbd_devices | join(',') }}"
                     - name: pcmk_delay_base
                       value: 30

   The settings specified in the example playbook include the following:

   ha_cluster_cluster_name: <cluster_name>

   The name of the cluster you are creating.

   ha_cluster_hacluster_password: <password>

   The password of the hacluster user. The hacluster user has full access to a cluster.

   ha_cluster_manage_firewall: true

   A variable that determines whether the ha_cluster RHEL system role manages the firewall.

   ha_cluster_manage_selinux: true

   A variable that determines whether the ha_cluster RHEL system role manages the ports of the firewall high availability service using the selinux RHEL system role.

   ha_cluster_sbd_enabled: true

   A variable that determines whether the cluster can use the SBD node fencing mechanism.

   ha_cluster_sbd_options: <sbd options>

   A list of name-value dictionaries specifying SBD options. For information about these options, see the Configuration via environment section of the sbd(8) man page on your system.

   ha_cluster_node_options: <node options>

   A variable that defines settings which vary from one cluster node to another. You can configure the following SBD and watchdog items:

   • sbd_watchdog_modules - Modules to be loaded, which create /dev/watchdog* devices.
   • sbd_watchdog_modules_blocklist - Watchdog kernel modules to be unloaded and blocked.
   • sbd_watchdog - Watchdog device to be used by SBD.
   • sbd_devices - Devices to use for exchanging SBD messages and for monitoring. Always refer to the devices using the long, stable device name (/dev/disk/by-id/).

   ha_cluster_cluster_properties: <cluster properties>

   A list of sets of cluster properties for Pacemaker cluster-wide configuration.

   ha_cluster_resource_primitives: <cluster resources>

   A list of resource definitions for the Pacemaker resources configured by the ha_cluster RHEL system role, including fencing resources.

   For details about all variables used in the playbook, see the /usr/share/ansible/roles/rhel-system-roles.ha_cluster/README.md file on the control node.

3. Validate the playbook syntax:

   $ ansible-playbook --syntax-check --ask-vault-pass ~/playbook.yml

   Note that this command only validates the syntax and does not protect against a wrong but valid configuration.

4. Run the playbook:

   $ ansible-playbook --ask-vault-pass ~/playbook.yml