skylab-ansible/playbooks/node-down.yaml

---
- name: Check cluster state
  hosts: cluster
  any_errors_fatal: true
  pre_tasks:
    - name: Configure remot execution environment
      ansible.builtin.import_tasks: tasks/meta/bootstrap-remote-env.yaml
  tasks:
    - name: Validate user input
      run_once: true
      ansible.builtin.assert:
        that:
          - node is defined
          - node in groups.cluster
        fail_msg: >-
          ERROR: Please set the 'node' variable to the cluster host to offline
          (one of: {{ groups.cluster | join(', ') }})          

    - name: Fetch node swarm ID
      ansible.builtin.command:
        cmd: !unsafe docker info --format '{{ .Swarm.NodeID}}'
      changed_when: false
      register: _docker_node_id_raw

    - name: Fetch swarm node availability
      ansible.builtin.command:
        cmd: docker node inspect {{ _docker_node_id_raw.stdout.strip() }} --format '{{ '{{ .Spec.Availability}}' }}'
      changed_when: false
      register: _docker_node_availability_raw

    - name: Set common facts
      ansible.builtin.set_fact:
        _target_node: "{{ node }}"
        _docker_node_id: "{{ _docker_node_id_raw.stdout.strip() }}"
        _docker_node_availability: "{{ _docker_node_availability_raw.stdout.strip() }}"
        # Use the next host in the group, unless that would exceed the length of the group,
        # in which case use the first host in the group
        _target_alt: >-
          {{ groups.cluster[
            lookup('ansible.utils.index_of', groups.cluster, 'eq', node) + 1
            if (lookup('ansible.utils.index_of', groups.cluster, 'eq', node) + 1) < (groups.cluster | length)
            else 0]
          }}          

    # I'm not sure how to do this without invoking a loop, so here we are
    - name: Set common fact for node addresses
      vars:
        _node_addresses:
          - "{{ lookup('vars', 'ansible_' + skylab_cluster.interface.access).ipv4.address }}"
      ansible.builtin.set_fact:
        _node_addresses: "{{ _node_addresses + [item.address] }}"
      loop: "{{ lookup('vars', 'ansible_' + skylab_cluster.interface.access).ipv4_secondaries }}"
      loop_control:
        label: "{{ item.address }}"

    - name: Set facts for target node
      when: inventory_hostname == _target_node
      ansible.builtin.set_fact:
        _needs_docker_migration: "{{ (_docker_node_availability | lower != 'drain') | bool }}"

    - name: Check cluster settings
      when: inventory_hostname != _target_node
      ansible.builtin.assert:
        that:
          - skylab_cluster.address.access | ansible.netcommon.ipaddr('address') in _node_addresses
          - _docker_node_availability | lower == 'active'
        fail_msg: >-
          ERROR: Node '{{ inventory_hostname }}' is already marked as unavailable. All cluster
          nodes must be available before a new node can be moved to unavailable status.          

- name: Offline node
  hosts: "{{ node }}"
  tasks:
    - name: Migrate services off target node
      when: _needs_docker_migration
      block:
        - name: Fetch current cluster service state
          ansible.builtin.command:
            cmd: !unsafe docker service ls --format '{{json .}}'
          changed_when: false
          register: _cluster_service_prestate

        - name: Disable NAT rule {{ _skylab_adguard_nat_rule }}
          delegate_to: core
          connection: ansible.netcommon.network_cli
          community.network.edgeos_config:
            lines:
              - set service nat rule {{ _skylab_adguard_nat_rule }} disable

        - name: Update node availability
          vars:
            ansible_python_interpreter: "{{ skylab_state_dir }}/ansible-runtime/bin/python"
          community.docker.docker_node:
            availability: drain
            hostname: "{{ _docker_node_id }}"
          register: _node_availability_status

        - name: Wait for services to shutdown
          ansible.builtin.pause:
            seconds: 10

        - name: Wait for services to migrate
          ansible.builtin.command:
            cmd: !unsafe docker service ls --format '{{json .}}'
          changed_when: false
          register: _cluster_service_poststate
          until: _cluster_service_poststate.stdout == _cluster_service_prestate.stdout
          retries: 120
          delay: 5

        - name: Enable NAT rule {{ _skylab_adguard_nat_rule }}
          delegate_to: core
          connection: ansible.netcommon.network_cli
          community.network.edgeos_config:
            lines:
              - delete service nat rule {{ _skylab_adguard_nat_rule }} disable
            save: true

    - name: Delete address from node
      become: true
      when: skylab_cluster.address.access | ansible.netcommon.ipaddr('address') in _node_addresses
      ansible.builtin.command:
        cmd: ip address delete {{ skylab_cluster.address.access | ansible.netcommon.ipaddr('host/prefix') }} dev {{ skylab_cluster.interface.access }}
      changed_when: true

    - name: Assign address to alt node
      delegate_to: "{{ _target_alt }}"
      become: true
      when: skylab_cluster.address.access | ansible.netcommon.ipaddr('address') not in hostvars[_target_alt]._node_addresses
      ansible.builtin.command:
        cmd: ip address add {{ skylab_cluster.address.access | ansible.netcommon.ipaddr('host/prefix') }} dev {{ hostvars[_target_alt].skylab_cluster.interface.access }}
      changed_when: true