r/samba-dc: Auto restart samba

Although it's rare, sometimes Samba crashes or fails to start.  When
this happens, restarting it is almost always enough to get it working
again.  Since all sorts of authentication problems can occur if one of
the domain controllers is down, it's probably best to just have systemd
automatically restart _samba.service_ if it ever stops for any reason.

roles/samba-dc/files/auto-restart.conf

@@ -0,0 +1,6 @@
+[Unit]
+StartLimitIntervalSec=60
+StartLimitBurst=10
+
+[Service]
+RestartSec=10s

roles/samba-dc/tasks/main.yml

@@ -77,6 +77,20 @@
     path=/etc/systemd/system/samba.service.d
     mode=0755
     state=directory
+  tags:
+  - systemd
+- name: ensure samba service auto restart is configurd
+  copy:
+    src: auto-restart.conf
+    dest: /etc/systemd/system/samba.service.d
+    owner: root
+    group: root
+    mode: u=rw,go=r
+  notify:
+  - reload systemd
+  - restart samba
+  tags:
+  - systemd
 
 - name: ensure samba starts at boot
   service: