net/nm: Apply global DNS options for static ifaces without DNS.

cloudinit/net/network_manager.py

@@ -246,7 +246,7 @@ def mac_addr(addr):
         """
         return addr.replace("-", ":").upper()
 
-    def render_interface(self, iface, renderer):
+    def render_interface(self, iface, network_state, renderer):
         """
         Integrate information from network state interface information
         into the connection. Most of the work is done here.
@@ -307,6 +307,7 @@ def render_interface(self, iface, renderer):
 
         device_mtu = iface["mtu"]
         ipv4_mtu = None
+        has_address = False
         found_nameservers = []
         found_dns_search = []
 
@@ -317,6 +318,7 @@ def render_interface(self, iface, renderer):
             self._set_ip_method(family, subnet["type"])
             if "address" in subnet:
                 self._add_address(family, subnet)
+                has_address = True
             if "gateway" in subnet:
                 self.config[family]["gateway"] = subnet["gateway"]
             for route in subnet["routes"]:
@@ -334,6 +336,14 @@ def render_interface(self, iface, renderer):
             found_nameservers = iface["dns"]["nameservers"]
             found_dns_search = iface["dns"]["search"]
 
+        # Now add in the global DNS information if we have an address but no
+        # DNS information yet
+        if has_address:
+            if not found_nameservers and network_state.dns_nameservers:
+                found_nameservers = network_state.dns_nameservers
+            if not found_dns_search and network_state.dns_searchdomains:
+                found_dns_search = network_state.dns_searchdomains
+
         for nameserver in found_nameservers:
             self._add_nameserver(nameserver)
         if found_dns_search:
@@ -453,7 +463,7 @@ def render_network_state(
         # Now render the actual interface configuration
         for iface in network_state.iter_interfaces():
             conn = self.connections[iface["name"]]
-            conn.render_interface(iface, self)
+            conn.render_interface(iface, network_state, self)
 
         # And finally write the files
         for con_id, conn in self.connections.items():

tests/unittests/test_net.py

@@ -646,6 +646,7 @@
 may-fail=false
 address1=172.19.1.34/22
 route1=0.0.0.0/0,172.19.3.254
+dns=172.19.0.12;
 
 """.lstrip(),
             ),
@@ -2822,6 +2823,8 @@
                 method=manual
                 may-fail=false
                 address1=192.168.200.7/24
+                dns=8.8.8.8;4.4.4.4;8.8.4.4;
+                dns-search=barley.maas;wark.maas;foobar.maas;
 
                 """
             ),
@@ -2930,12 +2933,15 @@
                 method=manual
                 may-fail=false
                 address1=192.168.14.2/24
+                dns=8.8.8.8;4.4.4.4;8.8.4.4;
+                dns-search=barley.maas;wark.maas;foobar.maas;
 
                 [ipv6]
                 method=manual
                 may-fail=false
                 address1=2001:1::1/64
                 route1=::/0,2001:4800:78ff:1b::1
+                dns-search=barley.maas;wark.maas;foobar.maas;
 
                 """
             ),