Add role for adding docker nodes to swarm

roles/swarm/tasks/join.yaml

@@ -0,0 +1,41 @@
+---
+- name: Fetch join token from existing manager
+  delegate_to: "{{ _docker_swarm_manager }}"
+  changed_when: false
+  ansible.builtin.command:
+    cmd: docker swarm join-token manager --quiet
+  register: _docker_swarm_join_token
+
+- name: Fetch manager addresses from existing manager
+  delegate_to: "{{ _docker_swarm_manager }}"
+  changed_when: false
+  ansible.builtin.command:
+    cmd: !unsafe docker info --format '{{json .Swarm.RemoteManagers}}'
+  register: _docker_swarm_manager_info_raw
+
+- name: Process manager addresses
+  vars:
+    _docker_swarm_manager_addresses: []
+  ansible.builtin.set_fact:
+    _docker_swarm_manager_addresses: "{{ _docker_swarm_manager_addresses + [item.Addr] }}"
+  loop: "{{ _docker_swarm_manager_info_raw.stdout | from_json }}"
+
+- name: Join node to swarm
+  vars:
+    ansible_python_interpreter: "{{ skylab_ansible_venv }}/bin/python"
+  community.docker.docker_swarm:
+    state: join
+    advertise_addr: "{{ lookup('vars', 'ansible_' + skylab_cluster.interface.internal).ipv4.address }}"
+    listen_addr: "{{ lookup('vars', 'ansible_' + skylab_cluster.interface.internal).ipv4.address }}"
+    remote_addrs: "{{ _docker_swarm_manager_addresses }}"
+    join_token: "{{ _docker_swarm_join_token.stdout.strip() }}"
+
+# For newly added nodes we don't want to have services be automatically scheduled on them
+# until the configuration is complete. The node-up playbook will be responsible for updating
+# the node to make it available in the cluster again
+- name: Update node to drain
+  vars:
+    ansible_python_interpreter: "{{ skylab_ansible_venv }}/bin/python"
+  community.docker.docker_node:
+    availability: drain
+    hostname: "{{ skylab_hostname }}"