add handler to reload existing wireguard interface

When new peers are added to the network, existing connections should not
be taken offline but interfaces should instead be edited in-flight.
This Commit adds and uses a handler that starts wireguard if not
running and afterwards reloads the peers from the configuration file
without taking down the wireguard interface.

handlers/main.yml

@@ -3,3 +3,5 @@
   service:
     name: "wg-quick@{{ wireguard_interface }}"
     state: restarted
+- name: start/reload wireguard
+  command: "bash -c 'systemctl start wg-quick@{{ wireguard_interface }}; wg syncconf {{ wireguard_interface}} <(wg-quick strip /etc/wireguard/{{ wireguard_interface }}.conf)'"

tasks/main.yml

@@ -99,7 +99,7 @@
   tags:
     - wg-config
   notify:
-    - restart wireguard
+    - start/reload wireguard
 
 - name: Check if reload-module-on-update is set
   stat: