nixos: Improve VM networking

nixos/boxes/colony/default.nix

@@ -28,7 +28,7 @@
 
     configuration = { lib, pkgs, modulesPath, config, systems, assignments, allAssignments, ... }:
       let
-        inherit (lib) mkIf mkMerge mkForce mapAttrs;
+        inherit (lib) mkIf mkMerge mkForce;
         inherit (lib.my) networkdAssignment;
       in
       {
@@ -77,10 +77,15 @@
                 Name = "base";
                 Kind = "bridge";
               };
+
               "25-vms".netdevConfig = {
                 Name = "vms";
                 Kind = "bridge";
               };
+              "30-vms-dummy".netdevConfig = {
+                Name = "vms0";
+                Kind = "dummy";
+              };
             };
 
             networks = {
@@ -119,19 +124,11 @@
                   ];
                 }
               ];
-
-              "80-vm-tap" = {
-                matchConfig = {
-                  # Don't think we have control over the name of the TAP from qemu-bridge-helper (or how to easily pick
-                  # which interface is which)
-                  Name = "tap*";
-                  Driver = "tun";
-                };
-                networkConfig = {
-                  KeepMaster = true;
-                  LLDP = true;
-                  EmitLLDP = "customer-bridge";
-                };
+              # Just so the vms interface will come up (in networkd's eyes), allowing dependant VMs to start.
+              # Could tweak the `waitOnline` for a single VM, but this seems better overall?
+              "80-vms-dummy" = {
+                matchConfig.Name = "vms0";
+                networkConfig.Bridge = "vms";
               };
             };
           };

nixos/boxes/colony/vms/default.nix

@@ -6,7 +6,8 @@
 
   nixos.systems.colony.configuration = { lib, pkgs, config, systems, ... }:
   let
-    inherit (lib) mkMerge;
+    inherit (builtins) listToAttrs;
+    inherit (lib) mkIf mkMerge optionals;
 
     wanBDF =
       if config.my.build.isDevVM then "00:02.0" else "01:00.0";
@@ -28,32 +29,18 @@
     };
   in
   {
-    systemd = {
-      services."vm@estuary" = {
-        # Depend the interface, networkd wait-online would deadlock...
-        requires = [ "sys-subsystem-net-devices-base.device" ];
-        preStart = ''
-          count=0
-          while ! ${pkgs.iproute2}/bin/ip link show dev base > /dev/null 2>&1; do
-              count=$((count+1))
-              if [ $count -ge 5 ]; then
-                echo "Timed out waiting for bridge interface"
-              fi
-              sleep 0.5
-          done
-        '';
-      };
-    };
-
     my = {
       vms = {
         instances = {
           estuary = {
             uuid = "59f51efb-7e6d-477b-a263-ed9620dbc87b";
-            networks.base.mac = "52:54:00:ab:f1:52";
+            networks.base = {
+              waitOnline = "no-carrier";
+              mac = "52:54:00:ab:f1:52";
+            };
             drives = {
               # TODO: Split into separate LVs
-              disk = {
+              disk = mkIf (!config.my.build.isDevVM) {
                 backend = {
                   driver = "host_device";
                   filename = "/dev/ssds/vm-estuary";
@@ -72,10 +59,7 @@
           shill = {
             uuid = "e34569ec-d24e-446b-aca8-a3b27abc1f9b";
             networks.vms.mac = "52:54:00:85:b3:b1";
-            drives = mkMerge [
-              (vmLVM "shill" "esp")
-              (vmLVM "shill" "nix")
-              (vmLVM "shill" "persist")
+            drives = mkMerge ([
               {
                 installer = {
                   backend = {
@@ -89,9 +73,13 @@
                     bootindex = 1;
                   };
                 };
-                esp.frontendOpts.bootindex = 0;
               }
-            ];
+            ] ++ (optionals (!config.my.build.isDevVM) [
+              (vmLVM "shill" "esp")
+              (vmLVM "shill" "nix")
+              (vmLVM "shill" "persist")
+              { esp.frontendOpts.bootindex = 0; }
+            ]));
           };
         };
       };