openvpn: T6478: Skip restart service when only client config changed

OpenVPN server reads per-client files from `--client-config-dir` at connect
time. When only `interfaces openvpn vtunN server client <client>`
entries are modified there is no need to send SIGHUP or restart
the service - the new CCD files written by `generate()` will
be picked up automatically on the next client connection.

1 files changed, 29 insertions, 1 deletions

diff --git a/src/conf_mode/interfaces_openvpn.py b/src/conf_mode/interfaces_openvpn.py
index ab27fe66e..d6b63ae2a 100755
--- a/src/conf_mode/interfaces_openvpn.py
+++ b/src/conf_mode/interfaces_openvpn.py
@@ -78,6 +78,28 @@ otp_file = '/config/auth/openvpn/{ifname}-otp-secrets'
 secret_chars = list('ABCDEFGHIJKLMNOPQRSTUVWXYZ234567')
 service_file = '/run/systemd/system/openvpn@{ifname}.service.d/20-override.conf'
 
+def _only_client_config_changed(conf, base, ifname):
+    """
+    Return True when the sole diff under this interface is a change to
+    `server.client` entries (i.e. CCD files).
+    """
+
+    iface_path = base + [ifname]
+    diff = get_config_diff(conf)
+
+    def _has_only_changes(path, node):
+        changes = diff.node_changed_children(path)
+        return len(changes) == 1 and changes[0] == node
+
+    # Something outside of 'server' also changed - not a CCD-only change
+    if _has_only_changes(iface_path, 'server'):
+        # Something outside of 'server.client' also changed - not a CCD-only change
+        if _has_only_changes(iface_path + ['server'], 'client'):
+            return True
+
+    return False
+
+
 def get_config(config=None):
     """
     Retrieve CLI config as dictionary. Dictionary can never be empty, as at least the
@@ -117,6 +139,12 @@ def get_config(config=None):
     if is_node_changed(conf, base + [ifname, 'enable-dco']):
         openvpn.update({'restart_required': {}})
 
+    # Detect changes that are limited to per-client CCD entries (T6478).
+    # OpenVPN reads client-config-dir files at connect time, so adding or
+    # updating them requires neither a SIGHUP nor a service restart.
+    if 'restart_required' not in openvpn and openvpn['mode'] == 'server':
+        openvpn['client_only_changed'] = _only_client_config_changed(conf, base, ifname)
+
     # We have to get the dict using 'get_config_dict' instead of 'get_interface_dict'
     # as 'get_interface_dict' merges the defaults in, so we can not check for defaults in there.
     tmp = conf.get_config_dict(base + [openvpn['ifname']], get_first_key=True)
@@ -818,7 +846,7 @@ def apply(openvpn):
     # No matching OpenVPN process running - maybe it got killed or none
     # existed - nevertheless, spawn new OpenVPN process
 
-    if not openvpn.get('no_restart_crl'):
+    if not openvpn.get('no_restart_crl') and not openvpn.get('client_only_changed'):
         action = 'reload-or-restart'
         if 'restart_required' in openvpn:
             action = 'restart'