nix/modules/hive-matrix.nix

@@ -342,47 +342,32 @@ in
           # tuwunel hard-fails to boot if `/etc/resolv.conf` has no
           # `nameserver` line (`Failed to configure DNS resolver ... no
           # nameservers found in config` → exit 1). This declarative
-          # nixos-container comes up with an EMPTY resolv.conf even with
-          # `networking.nameservers` set: the nixos-container default
-          # `useHostResolvConf = true` puts in-container resolvconf in
-          # host-tracking mode (ignores `networking.nameservers`, and never
-          # gets the host file across the shared-netns boundary), so it
-          # regenerates an empty file and tuwunel dies at boot.
+          # nixos-container had it come up EMPTY (just `options edns0`)
+          # even with `networking.nameservers` set: the nixos-container
+          # default `useHostResolvConf = true` puts in-container resolvconf
+          # in host-tracking mode, which ignores `networking.nameservers`
+          # and never receives the host's resolv.conf across the
+          # shared-netns boundary — so resolvconf regenerates an empty file
+          # and tuwunel dies at boot.
           #
-          # The earlier fix turned host-tracking off and trusted resolvconf
-          # to honour `networking.nameservers` — but that's a RUNTIME
-          # resolvconf behaviour, not verifiable at eval time, and it STILL
-          # came up empty in practice. So take resolvconf out of the
-          # loop entirely and write a STATIC `/etc/resolv.conf` from
-          # `bridgeIp` that nothing regenerates. Eval-proven: the generated
-          # `environment.etc."resolv.conf".text` is `nameserver <bridgeIp>`.
+          # When the hive network module is on, turn off host-tracking so
+          # resolvconf honours `networking.nameservers`, pointing the
+          # resolver at the dnsmasq the network module runs at `bridgeIp`.
           # This container always shares the host netns
-          # (`privateNetwork = false`), so it reaches `bridgeIp` regardless
-          # of `isolateContainers`. Network module off → inherit the host's
-          # resolv.conf. See `docs/network.md`.
+          # (`privateNetwork = false`), so it reaches `bridgeIp` whether or
+          # not `isolateContainers` is set. With the network module off,
+          # inherit the host's resolv.conf (which carries the host
+          # resolver). See `docs/network.md`.
           networking = lib.mkMerge [
             (lib.mkIf networkCfg.enable {
-              # resolvconf is taken out of the loop entirely; the static
-              # `environment.etc."resolv.conf"` below is the sole source of
-              # the resolver file (no `nameservers` — nothing would read it).
               useHostResolvConf = lib.mkForce false;
-              resolvconf.enable = lib.mkForce false;
+              nameservers = [ networkCfg.bridgeIp ];
             })
             (lib.mkIf (!networkCfg.enable) {
               useHostResolvConf = true;
             })
           ];
 
-          # resolvconf is disabled above, so write the static resolver file
-          # explicitly — NixOS won't synthesise one from `nameservers` once
-          # resolvconf is off, and this is the file tuwunel parses at boot.
-          environment.etc = lib.mkIf networkCfg.enable {
-            "resolv.conf".text = ''
-              nameserver ${networkCfg.bridgeIp}
-              options edns0
-            '';
-          };
-
           services.matrix-tuwunel = {
             enable = true;
             package = cfg.package;