[docker_swarm] enable easy way to add all hosts as workers to existing Docker Swarm

[bluepuma77]

SUMMARY

Enable easy way to add all hosts as workers to existing Docker Swarm

ISSUE TYPE

• Feature Idea

COMPONENT NAME

docker_swarm

ADDITIONAL INFORMATION

I can initialise a Docker Swarm with filtering all hosts for tag swarm_manager=true:

# hosts.ini
[all]
srv1 ansible_host=1.2.3.4 ansible_user=root swarm_manager=true
srv2 ansible_host=1.2.3.5 ansible_user=root
srv3 ansible_host=1.2.3.6 ansible_user=root swarm_manager=true
srv4 ansible_host=1.2.3.7 ansible_user=root
srv5 ansible_host=1.2.3.8 ansible_user=root swarm_manager=true
srv6 ansible_host=1.2.3.9 ansible_user=root

- hosts: all
  gather_facts: true

  tasks:
    - name: Init a new Docker Swarm on managers
      community.docker.docker_swarm:
        state: present
      when: hostvars[inventory_hostname]['swarm_manager'] | default(false) == "true"

How can I easily join the other hosts to the existing Docker Swarm as simple workers?

Is this a missing feature or just missing as an example?

state: present means manager and state: join means worker?

How to retrieve the join data from the manager nodes when iterating over worker nodes?

[niraami]

As far as I can tell, present is always init and join works for both managers and workers, just has to be the right token type.

The most concise way of doing this that I found is this:

- name: Initialize swarm
  community.docker.docker_swarm:
    state: present
  register: swarm_status
  when: inventory_hostname in groups['managers'][0]

- name: Connect to Docker Swarm as a Manager
  community.docker.docker_swarm:
    state: join
    timeout: 60
    join_token: "{{ hostvars[groups['managers'][0]].swarm_status['swarm_facts']['JoinTokens']['Manager']}}"
    remote_addrs: "{{ hostvars[groups['managers'][0]]['ansible_default_ipv4']['address'] }}:2377"
  when: inventory_hostname in groups['managers'] and inventory_hostname not in groups['managers'][0]

- name: Connect to Docker Swarm as a Worker
  community.docker.docker_swarm:
    state: join
    timeout: 60
    join_token: "{{ hostvars[groups['managers'][0]].swarm_status['swarm_facts']['JoinTokens']['Worker'] }}"
    remote_addrs: "{{ hostvars[groups['managers'][0]]['ansible_default_ipv4']['address'] }}:2377"
  when: inventory_hostname in groups['workers']

With the inventory being structured like this:

all:
  children:
    managers:
      hosts:
        host-1
        host-2
    workers:
      hosts:
        host-3
        host-4