Merge master into staging

nixos/modules/virtualisation/google-compute-image.nix

@@ -57,6 +57,12 @@ in
   # Always include cryptsetup so that NixOps can use it.
   environment.systemPackages = [ pkgs.cryptsetup ];
 
+  # Make sure GCE image does not replace host key that NixOps sets
+  environment.etc."default/instance_configs.cfg".text = lib.mkDefault ''
+    [InstanceSetup]
+    set_host_keys = false
+  '';
+
   # Rely on GCP's firewall instead
   networking.firewall.enable = mkDefault false;
 
@@ -69,6 +75,9 @@ in
 
   networking.usePredictableInterfaceNames = false;
 
+  # GC has 1460 MTU
+  networking.interfaces.eth0.mtu = 1460;
+
   # allow the google-accounts-daemon to manage users
   users.mutableUsers = true;
   # and allow users to sudo without password