swarm.yml

---
# determine the status of each manager node and break them
# into two groups:
#   - swarm_manager_operational (swarm is running and active)
#   - swarm_manager_bootstrap (host needs to be joined to the cluster)
- hosts: manager
  become: true
  tasks:
    - name: determine swarm status
      shell: >
        docker info --format \{\{.Swarm.LocalNodeState\}\}
      register: swarm_status

    - name: create swarm_manager_operational group
      add_host:
        hostname: "{{ item }}"
        groups: swarm_manager_operational
      with_items: "{{ ansible_play_hosts | default(play_hosts) }}"
      when: "'active' in hostvars[item].swarm_status.stdout_lines"
      run_once: true

    - name: create swarm_manager_bootstrap group
      add_host:
        hostname: "{{ item }}"
        groups: swarm_manager_bootstrap
      with_items: "{{ ansible_play_hosts | default(play_hosts) }}"
      when: "'active' not in hostvars[item].swarm_status.stdout_lines"
      run_once: true

# determine the status of each worker node and break them
# into two groups:
#   - swarm_worker_operational (host is joined to the swarm cluster)
#   - swarm_worker_bootstrap (host needs to be joined to the cluster)
- hosts: worker
  become: true
  tasks:
    - name: determine swarm status
      shell: >
        docker info --format \{\{.Swarm.LocalNodeState\}\}
      register: swarm_status

    - name: create swarm_worker_operational group
      add_host:
        hostname: "{{ item }}"
        groups: swarm_worker_operational
      with_items: "{{ ansible_play_hosts | default(play_hosts) }}"
      when: "'active' in hostvars[item].swarm_status.stdout_lines"
      run_once: true

    - name: create swarm_worker_bootstrap group
      add_host:
        hostname: "{{ item }}"
        groups: swarm_worker_bootstrap
      with_items: "{{ ansible_play_hosts | default(play_hosts) }}"
      when: "'active' not in hostvars[item].swarm_status.stdout_lines"
      run_once: true

# when the swarm_manager_operational group is empty, meaning there
# are no hosts running swarm, we need to initialize one of the hosts
# then add it to the swarm_manager_operational group
- hosts: swarm_manager_bootstrap[0]
  become: true
  tasks:
    - name: initialize swarm cluster
      shell: >
        docker swarm init
        --advertise-addr={{ hostvars[inventory_hostname]['ansible_default_ipv4']['address'] }}:2377
      when: "'swarm_manager_operational' not in groups"
      register: bootstrap_first_node

    - name: add initialized host to swarm_manager_operational group
      add_host:
        hostname: "{{ item }}"
        groups: swarm_manager_operational
      with_items: "{{ ansible_play_hosts | default(play_hosts) }}"
      when: bootstrap_first_node | changed

# retrieve the swarm tokens and populate a list of ips listening on
# the swarm port 2377
- hosts: swarm_manager_operational[0]
  become: true
  vars:
    iface: "{{ swarm_iface | default('eth0') }}"
  tasks:
    - name: retrieve swarm manager token
      shell: docker swarm join-token -q manager
      register: swarm_manager_token

    - name: retrieve swarm worker token
      shell: docker swarm join-token -q worker
      register: swarm_worker_token

    - name: populate list of manager ips
      add_host:
        hostname: "{{ hostvars[item]['ansible_default_ipv4']['address'] }}"
        groups: swarm_manager_ips
      with_items: "{{ ansible_play_hosts | default(play_hosts) }}"

# join the manager hosts not yet initialized to the swarm cluster
- hosts: swarm_manager_bootstrap:!swarm_manager_operational
  become: true
  vars:
    token: "{{ hostvars[groups['swarm_manager_operational'][0]]['swarm_manager_token']['stdout'] }}"
  tasks:
    - name: join manager nodes to cluster
      shell: >
        docker swarm join
        --advertise-addr={{ swarm_iface | default('eth0') }}:2377
        --token={{ token }}
        {{ groups['swarm_manager_ips'][0] }}:2377

# join the worker hosts not yet initialized to the swarm cluster
- hosts: swarm_worker_bootstrap
  become: true
  vars:
    token: "{{ hostvars[groups['swarm_manager_operational'][0]]['swarm_worker_token']['stdout'] }}"
  tasks:
    - name: join worker nodes to cluster
      shell: >
        docker swarm join
        --advertise-addr={{ swarm_iface | default('eth0') }}:2377
        --token={{ token }}
        {{ groups['swarm_manager_ips'][0] }}:2377