Add hostfile management to server role

Add aliases for direct connections of the cluster servers

inventory.yaml

@@ -34,6 +34,13 @@ en1:
           - server
           - docker-swarm
           - datastore
+        skylab_direct_peers:
+          - hostname: pegasus.local
+            address: 192.168.42.10
+          - hostname: saturn.local
+            address: 192.168.42.20
+          - hostname: orion.local
+            address: 192.168.42.30
 
       hosts:
         pegasus:  # jupiter

roles/server/tasks/hosts.yaml

@@ -0,0 +1,34 @@
+---
+- name: Retrieve current hostsfile contents
+  ansible.builtin.command:
+    cmd: cat /etc/hosts
+  changed_when: false
+  register: _existing_hostsfile_raw
+
+- name: Assemble hostsfile lines
+  vars:
+    _hostsfile_lines: []
+  ansible.builtin.set_fact:
+    _hostsfile_lines: "{{ _hostsfile_lines + [item.address + '   ' + item.hostname] }}"
+  loop: "{{ skylab_direct_peers }}"
+  loop_control:
+    label: "{{ item.hostname }}"
+
+- name: Configure directly connected peers
+  become: true
+  ansible.builtin.lineinfile:
+    path: /etc/hosts
+    line: "{{ item }}"
+    state: present
+  loop: "{{ _hostsfile_lines }}"
+  loop_control:
+    label: "{{ item.partition(' ')[0] }}"
+
+- name: Remove unmanaged peer aliases
+  become: true
+  when: "'localhost' not in item and item not in _hostsfile_lines"
+  ansible.builtin.lineinfile:
+    path: /etc/hosts
+    line: "{{ item }}"
+    state: absent
+  loop: "{{ _existing_hostsfile_raw.stdout_lines }}"

roles/server/tasks/main.yaml

@@ -8,3 +8,7 @@
 - name: Configure network settings
   when: skylab_networking is defined
   ansible.builtin.include_tasks: networkd.yaml
+
+- name: Configure hostsfile
+  when: skylab_direct_peers is defined
+  ansible.builtin.include_tasks: hosts.yaml