11.13. Configuring a placement strategy for a high availability cluster by using the RHEL ha_cluster RHEL system role

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 utilization attributes
         ansible.builtin.include_role:
           name: redhat.rhel_system_roles.ha_cluster
         vars:
             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_cluster_properties:
               - attrs:
                   - name: placement-strategy
                     value: utilization
             ha_cluster_node_options:
               - node_name: node1
                 utilization:
                   - attrs:
                       - name: utilization1
                         value: 1
                       - name: utilization2
                         value: 2
               - node_name: node2
                 utilization:
                   - attrs:
                       - name: utilization1
                         value: 3
                       - name: utilization2
                         value: 4
             ha_cluster_resource_primitives:
               - id: resource1
                 agent: 'ocf:pacemaker:Dummy'
                 utilization:
                   - attrs:
                       - name: utilization1
                         value: 2
                       - name: utilization2
                         value: 3

   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_cluster_properties: <cluster properties>

   List of sets of cluster properties for Pacemaker cluster-wide configuration. For utilization to have an effect, the placement-strategy property must be set and its value must be different from the value default.

   `ha_cluster_node_options: <node options>

   A variable that defines various settings which vary from cluster node to cluster node.

   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