ceph-ansible/infrastructure-playbooks/shrink-mgr.yml

---
# This playbook shrinks the Ceph manager from your cluster
#
# Use it like this:
# ansible-playbook shrink-mgr.yml -e mgr_to_kill=ceph-mgr1
#     Prompts for confirmation to shrink, defaults to no and
#     doesn't shrink the cluster and yes shrinks the cluster.
#
# ansible-playbook -e ireallymeanit=yes|no shrink-mgr.yml
#     Overrides the prompt using -e option. Can be used in
#     automation scripts to avoid interactive prompt.


- name: gather facts and check the init system
  hosts:
    - "{{ mon_group_name | default('mons') }}"
    - "{{ mgr_group_name | default('mgrs') }}"
  become: true
  tasks:
    - debug:
        msg: gather facts on all Ceph hosts for following reference

- name: confirm if user really meant to remove manager from the ceph cluster
  hosts: localhost
  become: true
  vars_prompt:
    - name: ireallymeanit
      prompt: Are you sure you want to shrink the cluster?
      default: 'no'
      private: no
  pre_tasks:
    - import_role:
        name: ceph-defaults

    - import_role:
        name: ceph-facts

    - name: set_fact container_exec_cmd
      when: containerized_deployment | bool
      set_fact:
        container_exec_cmd: "{{ container_binary }} exec ceph-mon-{{ hostvars[groups[mon_group_name][0]]['ansible_hostname'] }}"

    - name: exit playbook, if can not connect to the cluster
      command: "{{ container_exec_cmd | default('') }} timeout 5 ceph --cluster {{ cluster }} health"
      register: ceph_health
      until: ceph_health.rc
      failed_when: ceph_health.rc != 0
      delegate_to: "{{ groups[mon_group_name][0] }}"
      retries: 5
      delay: 2

    - name: get total number of mgrs in cluster
      block:
        - name: save mgr dump output
          command: "{{ container_exec_cmd | default('') }} ceph --cluster {{cluster}} mgr dump"
          register: mgr_dump
          delegate_to: "{{ groups[mon_group_name][0] }}"

        - name: get a list of names of standby mgrs
          set_fact:
            standby_mgrs: "{{ (mgr_dump.stdout | from_json)['standbys'] | map(attribute='name') | list }}"

        - name: get active mgr
          set_fact:
            active_mgr: "{{ [mgr_dump.stdout | from_json] | map(attribute='active_name') | list }}"

    - name: exit playbook, if there's no standby manager
      fail:
        msg: "You are about to shrink the only manager present in the cluster."
      when: standby_mgrs | length | int < 1

    - name: exit playbook, if no manager was given
      fail:
        msg: "mgr_to_kill must be declared
              Exiting shrink-cluster playbook, no manager was removed.
              On the command line when invoking the playbook, you can use
              -e mgr_to_kill=ceph-mgr01 argument. You can only remove a single
              manager each time the playbook runs."
      when: mgr_to_kill is not defined

    - name: exit playbook, if the manager is not part of the inventory
      fail:
        msg: "It seems that the host given is not part of your inventory,
              please make sure it is."
      when:
        - mgr_to_kill not in active_mgr
        - mgr_to_kill not in standby_mgrs

    - name: exit playbook, if user did not mean to shrink cluster
      fail:
        msg: "Exiting shrink-mgr playbook, no manager was removed.
           To shrink the cluster, either say 'yes' on the prompt or
           or use `-e ireallymeanit=yes` on the command line when
           invoking the playbook"
      when: ireallymeanit != 'yes'

    - name: set_fact mgr_to_kill_hostname
      set_fact:
        mgr_to_kill_hostname: "{{ hostvars[mgr_to_kill]['ansible_hostname'] }}"

  tasks:
    - name: stop manager services and verify it
      block:
        - name: stop manager service
          service:
            name: ceph-mgr@{{ mgr_to_kill_hostname }}
            state: stopped
            enabled: no
          delegate_to: "{{ mgr_to_kill }}"
          failed_when: false

        - name: ensure that the mds is stopped
          command: "systemctl is-active ceph_mds@{{ mgr_to_kill_hostname }}"
          register: mgr_to_kill_status
          failed_when: mgr_to_kill_status.rc == 0
          delegate_to: "{{ mgr_to_kill }}"
          retries: 5
          delay: 2

    - name: fail if the mgr is reported in ceph status
      command: "{{ container_exec_cmd | default('') }} ceph --cluster {{ cluster }} -s -f json | grep {{ mgr_to_kill }}"
      register: mgr_in_ceph_status
      failed_when: mgr_in_ceph_status.rc == 0
      delegate_to: "{{ groups[mon_group_name][0] }}"
      retries: 3
      delay: 5

    - name: purge manager store
      file:
        path: /var/lib/ceph/mgr/{{ cluster }}-{{ mgr_to_kill_hostname }}
        state: absent
      delegate_to: "{{ mgr_to_kill }}"

  post_tasks:
    - name: show ceph health
      command: "{{ container_exec_cmd | default('') }} ceph --cluster {{ cluster }} -s"
      delegate_to: "{{ groups[mon_group_name][0] }}"