nixos-module/container/bird: rework radv router selection

config/net/c3d2.nix

@@ -67,6 +67,7 @@
       c3d2-gw3 = "172.22.99.4";
       dn42 = "172.22.99.253";
     };
+    ipv6Router = "c3d2-gw3";
     hosts6.dn42 = {
       bgp = "fd23:42:c3d2:523::c3d2:ff0b";
       c3d2-anon = "fd23:42:c3d2:523::c3d2:1";

config/net/cluster.nix

@@ -4,6 +4,7 @@ let
 in
 {
   site.net.cluster = {
+    ipv6Router = "cls-gw";
     domainName = "cluster.zentralwerk.org";
     extraRecords = map (host: {
       data = "1 1 6789 ${host}";

config/net/flpk.nix

@@ -1,6 +1,7 @@
 {
   site.net.flpk = {
     domainName = "flpk.zentralwerk.org";
+    ipv6Router = "flpk-gw";
     subnet4 = "45.158.40.160/27";
     # we get a /56
     subnets6.flpk = "2a0f:5382:acab:1400::/64";

config/net/serv.nix

@@ -79,6 +79,7 @@
       factorio = "172.20.73.73";
       zengel = "172.20.73.74";
     };
+    ipv6Router = "serv-gw";
     subnets6.dn42 = "fd23:42:c3d2:582::/64";
     subnets6.up4 = "2a00:8180:2c00:282::/64";
     hosts6.dn42 = {

config/net/vpn.nix

@@ -3,6 +3,7 @@
   site.net.vpn = {
     vlan = null;
     domainName = "core.zentralwerk.org";
+    ipv6Router = "vpn-gw";
     hosts4 = {
       vpn-gw = "172.20.76.225";
     };

nix/lib/config/options.nix

@@ -158,6 +158,11 @@ let
         type = with types; nullOr (submodule { options = dhcpOpts; });
         default = null;
       };
+      ipv6Router = mkOption {
+        description = "Who sends router advertisements?";
+        type = with types; nullOr str;
+        default = config.site.net.${name}.dhcp.router or null;
+      };
       domainName = mkOption {
         description = "Domain name option";
         type = types.str;

nix/nixos-module/container/bird.nix

@@ -12,17 +12,11 @@ let
 
   isUpstream = upstreamInterfaces != {};
 
-  # Configuring a gateway? If so, this is the associated net.
-  gatewayNet =
-    let
-      m = builtins.match "(.+)-gw" hostName;
-    in if hostName == "c3d2-gw3"
-       then "c3d2"
-       else if m == [ "cls" ]
-       then "cluster"
-       else if m == null
-       then null
-       else builtins.head m;
+  ipv6RouterNets = builtins.attrNames (
+    lib.filterAttrs (net: { ipv6Router, ... }:
+      ipv6Router == hostName
+    ) config.site.net
+  );
 
   enumerate = n: list:
     if list == []
@@ -110,26 +104,28 @@ in
         }
       ''}
 
-      ${lib.optionalString (gatewayNet != null) ''
+      ${lib.optionalString (ipv6RouterNets != []) ''
         # Router advertisements
         protocol radv {
           rdnss ${config.site.net.serv.hosts6.dn42.dnscache};
 
-          interface "${gatewayNet}" {
-            min ra interval 10;
-            max ra interval 60;
+          ${lib.concatMapStrings (net:
+            interface "${net}" {
+              min ra interval 10;
+              max ra interval 60;
 
-            ${builtins.concatStringsSep "\n" (
-              map (subnet6: ''
-                prefix ${subnet6} {
-                  preferred lifetime 600;
-                  valid lifetime 1800;
-                };
-              '') (builtins.attrValues config.site.net.${gatewayNet}.subnets6)
-            )}
+              ${builtins.concatStringsSep "\n" (
+                map (subnet6: ''
+                  prefix ${subnet6} {
+                    preferred lifetime 600;
+                    valid lifetime 1800;
+                  };
+                '') (builtins.attrValues config.site.net.${net}.subnets6)
+              )}
 
-            dnssl "${config.site.net.${gatewayNet}.domainName}";
-          };
+              dnssl "${config.site.net.${net}.domainName}";
+            };
+          ) ipv6RouterNets}
         }
       ''}