bundles/postfix: fix some needed files not being present in chroot on arch

bundles/postfix/files/arch-override.conf

@@ -0,0 +1,6 @@
+[Service]
+# arch postfix is not set up for chrooting by default
+ExecStartPre=-/usr/sbin/mkdir -p /var/spool/postfix/etc
+% for file in ['/etc/localtime', '/etc/nsswitch.conf', '/etc/resolv.conf', '/etc/services']:
+ExecStartPre=-/usr/sbin/cp -p ${file} /var/spool/postfix${file}
+% endfor

bundles/postfix/items.py

@@ -21,7 +21,7 @@ for identifier in node.metadata.get('postfix/mynetworks', set()):
             netmask = '128'
         mynetworks.add(f'[{ip6}]/{netmask}')
 
-my_package = 'pkg_pacman:postfix' if node.has_bundle('pacman') else 'pkg_apt:postfix'
+my_package = 'pkg_pacman:postfix' if node.os == 'arch' else 'pkg_apt:postfix'
 
 files = {
     '/etc/mailname': {
@@ -86,3 +86,13 @@ svc_systemd = {
         },
     },
 }
+
+if node.os == 'arch':
+    files['/etc/systemd/system/postfix.service.d/bundlewrap.conf'] = {
+        'source': 'arch-override.conf',
+        'content_type': 'mako',
+        'triggers': {
+            'action:systemd-reload',
+            'svc_systemd:postfix:restart',
+        },
+    }