Merge pull request #88032 from flokli/scripted-networking-link

nixos/scripted-networking: use udev to configure link MACAddress and MTUBytes

nixos/doc/manual/release-notes/rl-2009.xml

@@ -437,6 +437,21 @@ systemd.services.nginx.serviceConfig.ReadWritePaths = [ "/var/www" ];
      Default algorithm for ZRAM swap was changed to <literal>zstd</literal>.
    </para>
    </listitem>
+   <listitem>
+    <para>
+     The scripted networking system now uses <literal>.link</literal> files in
+     <literal>/etc/systemd/network</literal> to configure mac address and link MTU,
+     instead of the sometimes buggy <literal>network-link-*</literal> units, which
+     have been removed.
+     Bringing the interface up has been moved to the beginning of the
+     <literal>network-addresses-*</literal> unit.
+     Note this doesn't require <command>systemd-networkd</command> - it's udev that
+     parses <literal>.link</literal> files.
+     Extra care needs to be taken in the presence of <link xlink:href="https://wiki.debian.org/NetworkInterfaceNames#THE_.22PERSISTENT_NAMES.22_SCHEME">legacy udev rules</link>
+     to rename interfaces, as MAC Address and MTU defined in these options can only match on the original link name.
+     In such cases, you most likely want to create a <literal>10-*.link</literal> file through <xref linkend="opt-systemd.network.links"/> and set both name and MAC Address / MTU there.
+    </para>
+   </listitem>
   </itemizedlist>
  </section>
 </section>

nixos/modules/tasks/network-interfaces-scripted.nix

@@ -54,7 +54,16 @@ let
     };
 
   normalConfig = {
-
+    systemd.network.links = let
+      createNetworkLink = i: nameValuePair "40-${i.name}" {
+        matchConfig.OriginalName = i.name;
+        linkConfig = optionalAttrs (i.macAddress != null) {
+          MACAddress = i.macAddress;
+        } // optionalAttrs (i.mtu != null) {
+          MTUBytes = toString i.mtu;
+        };
+      };
+    in listToAttrs (map createNetworkLink interfaces);
     systemd.services =
       let
 
@@ -164,7 +173,6 @@ let
           { description = "Address configuration of ${i.name}";
             wantedBy = [
               "network-setup.service"
-              "network-link-${i.name}.service"
               "network.target"
             ];
             # order before network-setup because the routes that are configured
@@ -183,6 +191,8 @@ let
                 state="/run/nixos/network/addresses/${i.name}"
                 mkdir -p $(dirname "$state")
 
+                ip link set "${i.name}" up
+
                 ${flip concatMapStrings ips (ip:
                   let
                     cidr = "${ip.address}/${toString ip.prefixLength}";
@@ -237,38 +247,6 @@ let
             '';
           };
 
-        createNetworkLink = i:
-        let
-          deviceDependency = if (config.boot.isContainer || i.name == "lo")
-            then []
-            else [ (subsystemDevice i.name) ];
-        in
-        nameValuePair "network-link-${i.name}"
-        { description = "Link configuration of ${i.name}";
-          wantedBy = [ "network-interfaces.target" ];
-          before = [ "network-interfaces.target" ];
-          bindsTo = deviceDependency;
-          after = [ "network-pre.target" ] ++ deviceDependency;
-          path = [ pkgs.iproute ];
-          serviceConfig = {
-            Type = "oneshot";
-            RemainAfterExit = true;
-          };
-          script =
-            ''
-              echo "Configuring link..."
-            '' + optionalString (i.macAddress != null) ''
-              echo "setting MAC address to ${i.macAddress}..."
-              ip link set "${i.name}" address "${i.macAddress}"
-            '' + optionalString (i.mtu != null) ''
-              echo "setting MTU to ${toString i.mtu}..."
-              ip link set "${i.name}" mtu "${toString i.mtu}"
-            '' + ''
-              echo -n "bringing up interface... "
-              ip link set "${i.name}" up && echo "done" || (echo "failed"; exit 1)
-            '';
-        };
-
         createTunDevice = i: nameValuePair "${i.name}-netdev"
           { description = "Virtual Network Interface ${i.name}";
             bindsTo = [ "dev-net-tun.device" ];
@@ -298,7 +276,7 @@ let
             bindsTo = deps ++ optional v.rstp "mstpd.service";
             partOf = [ "network-setup.service" ] ++ optional v.rstp "mstpd.service";
             after = [ "network-pre.target" ] ++ deps ++ optional v.rstp "mstpd.service"
-              ++ concatMap (i: [ "network-addresses-${i}.service" "network-link-${i}.service" ]) v.interfaces;
+              ++ map (i: "network-addresses-${i}.service") v.interfaces;
             before = [ "network-setup.service" ];
             serviceConfig.Type = "oneshot";
             serviceConfig.RemainAfterExit = true;
@@ -375,7 +353,7 @@ let
         createVswitchDevice = n: v: nameValuePair "${n}-netdev"
           (let
             deps = concatLists (map deviceDependency (attrNames (filterAttrs (_: config: config.type != "internal") v.interfaces)));
-            internalConfigs = concatMap (i: ["network-link-${i}.service" "network-addresses-${i}.service"]) (attrNames (filterAttrs (_: config: config.type == "internal") v.interfaces));
+            internalConfigs = map (i: "network-addresses-${i}.service") (attrNames (filterAttrs (_: config: config.type == "internal") v.interfaces));
             ofRules = pkgs.writeText "vswitch-${n}-openFlowRules" v.openFlowRules;
           in
           { description = "Open vSwitch Interface ${n}";
@@ -427,7 +405,7 @@ let
             bindsTo = deps;
             partOf = [ "network-setup.service" ];
             after = [ "network-pre.target" ] ++ deps
-              ++ concatMap (i: [ "network-addresses-${i}.service" "network-link-${i}.service" ]) v.interfaces;
+              ++ map (i: "network-addresses-${i}.service") v.interfaces;
             before = [ "network-setup.service" ];
             serviceConfig.Type = "oneshot";
             serviceConfig.RemainAfterExit = true;
@@ -540,7 +518,6 @@ let
           });
 
       in listToAttrs (
-           map createNetworkLink interfaces ++
            map configureAddrs interfaces ++
            map createTunDevice (filter (i: i.virtual) interfaces))
          // mapAttrs' createBridgeDevice cfg.bridges