Adding or removing hosts

Use the following procedure to add new hosts to the cluster:

1. Log in to the Ansible administration node.

2. Navigate to the /usr/share/cephadm-ansible directory on the Ansible administration node:

   Example

   [ansible@admin ~]$ cd /usr/share/cephadm-ansible

3. Add the new hosts and labels to the Ansible inventory file.

   Syntax

   sudo vi INVENTORY_FILE
   
   NEW_HOST1 labels="['LABEL1', 'LABEL2']"
   NEW_HOST2 labels="['LABEL1', 'LABEL2']"
   NEW_HOST3 labels="['LABEL1']"
   
   [admin]
   ADMIN_HOST monitor_address=MONITOR_IP_ADDRESS labels="['ADMIN_LABEL', 'LABEL1', 'LABEL2']"

   Example

   [ansible@admin cephadm-ansible]$ sudo vi hosts
   
   host02 labels="['mon', 'mgr']"
   host03 labels="['mon', 'mgr']"
   host04 labels="['osd']"
   host05 labels="['osd']"
   host06 labels="['osd']"
   
   [admin]
   host01 monitor_address= 10.10.128.68 labels="['_admin', 'mon', 'mgr']"

   Note: If you have previously added the new hosts to the Ansible inventory file and ran the preflight playbook on the hosts, skip to step 3.

4. Run the preflight playbook with the --limit option:

   Syntax

   ansible-playbook -i INVENTORY_FILE cephadm-preflight.yml --extra-vars "ceph_origin=ibm" --limit NEWHOST

   Example

   [ansible@admin cephadm-ansible]$ ansible-playbook -i hosts cephadm-preflight.yml --extra-vars "ceph_origin=ibm" --limit host02

   The preflight playbook installs podman, lvm2, chrony, and cephadm on the new host. After installation is complete, cephadm resides in the /usr/sbin/ directory.

5. Create a playbook to add the new hosts to the cluster:

   Syntax

   sudo vi PLAYBOOK_FILENAME.yml
   
   ---
   - name: PLAY_NAME
     hosts: HOSTS_OR_HOST_GROUPS
     become: USE_ELEVATED_PRIVILEGES
     gather_facts: GATHER_FACTS_ABOUT_REMOTE_HOSTS
     tasks:
       - name: NAME_OF_TASK
         ceph_orch_host:
           name: "{{ ansible_facts[hostname] }}"
           address: "{{ ansible_facts[default_ipv4][address] }}"
           labels: "{{ labels }}"
         delegate_to: HOST_TO_DELEGATE_TASK_TO
   
       - name: NAME_OF_TASK
         when: inventory_hostname in groups[admin]
         ansible.builtin.shell:
           cmd: CEPH_COMMAND_TO_RUN
         register: REGISTER_NAME
   
       - name: NAME_OF_TASK
         when: inventory_hostname in groups[admin]
         debug:
           msg: "{{ REGISTER_NAME.stdout }}"

   Note: By default, Ansible runs all tasks on the host that matches the hosts line of your playbook. The ceph orch commands must run on the host that contains the admin keyring and the Ceph configuration file. Use the delegate_to keyword to specify the admin host in your cluster.

   Example

   [ansible@admin cephadm-ansible]$ sudo vi add-hosts.yml
   
   ---
   - name: add additional hosts to the cluster
     hosts: all
     become: true
     gather_facts: true
     tasks:
       - name: add hosts to the cluster
         ceph_orch_host:
           name: "{{ ansible_facts['hostname'] }}"
           address: "{{ ansible_facts['default_ipv4']['address'] }}"
           labels: "{{ labels }}"
         delegate_to: host01
   
       - name: list hosts in the cluster
         when: inventory_hostname in groups['admin']
         ansible.builtin.shell:
           cmd: ceph orch host ls
         register: host_list
   
       - name: print current list of hosts
         when: inventory_hostname in groups['admin']
         debug:
           msg: "{{ host_list.stdout }}"

   In this example, the playbook adds the new hosts to the cluster and displays a current list of hosts.

6. Run the playbook to add additional hosts to the cluster:

   Syntax

   ansible-playbook -i INVENTORY_FILE PLAYBOOK_FILENAME.yml

   Example

   [ansible@admin cephadm-ansible]$ ansible-playbook -i hosts add-hosts.yml

Use the following procedure to remove hosts from the cluster:

1. Log in to the Ansible administration node.

2. Navigate to the /usr/share/cephadm-ansible directory on the Ansible administration node:

   Example

   [ansible@admin ~]$ cd /usr/share/cephadm-ansible

3. Create a playbook to remove a host or hosts from the cluster:

   Syntax

   sudo vi PLAYBOOK_FILENAME.yml
   
   ---
   - name: NAME_OF_PLAY
     hosts: ADMIN_HOST
     become: USE_ELEVATED_PRIVILEGES
     gather_facts: GATHER_FACTS_ABOUT_REMOTE_HOSTS
     tasks:
       - name: NAME_OF_TASK
         ceph_orch_host:
           name: HOST_TO_REMOVE
           state: STATE
   
       - name: NAME_OF_TASK
         ceph_orch_host:
           name: HOST_TO_REMOVE
           state: STATE
         retries: NUMBER_OF_RETRIES
         delay: DELAY
         until: CONTINUE_UNTIL
         register: REGISTER_NAME
   
       - name: NAME_OF_TASK
         ansible.builtin.shell:
           cmd: ceph orch host ls
         register: REGISTER_NAME
   
       - name: NAME_OF_TASK
           debug:
             msg: "{{ REGISTER_NAME.stdout }}"

   Example

   [ansible@admin cephadm-ansible]$ sudo vi remove-hosts.yml
   
   ---
   - name: remove host
     hosts: host01
     become: true
     gather_facts: true
     tasks:
       - name: drain host07
         ceph_orch_host:
           name: host07
           state: drain
   
       - name: remove host from the cluster
         ceph_orch_host:
           name: host07
           state: absent
         retries: 20
         delay: 1
         until: result is succeeded
         register: result
   
        - name: list hosts in the cluster
          ansible.builtin.shell:
            cmd: ceph orch host ls
          register: host_list
   
        - name: print current list of hosts
          debug:
            msg: "{{ host_list.stdout }}"

In this example, the playbook tasks drain all daemons on host07, removes the host from the cluster, and displays a current list of hosts.

Run the playbook to remove host from the cluster:

Syntax

 ansible-playbook -i INVENTORY_FILE PLAYBOOK_FILENAME.yml

Example

 [ansible@admin cephadm-ansible]$ ansible-playbook -i hosts remove-hosts.yml