i2p/yggdrasil: factor out and only enable for desko/servo

especially this means i no longer run them on moby, improving battery life & such

hosts/by-name/desko/default.nix

@@ -7,6 +7,7 @@
   sops.secrets.colin-passwd.neededForUsers = true;
 
   sane.roles.build-machine.enable = true;
+  sane.roles.ac = true;
   sane.roles.client = true;
   sane.roles.dev-machine = true;
   sane.services.wg-home.enable = true;

hosts/by-name/lappy/default.nix

@@ -4,8 +4,6 @@
     ./fs.nix
   ];
 
-  sane.yggdrasil.enable = true;
-
   sane.roles.client = true;
   sane.roles.dev-machine = true;
   sane.services.wg-home.enable = true;

hosts/by-name/servo/default.nix

@@ -14,6 +14,7 @@
     signaldctl.enableFor.user.colin = true;
   };
 
+  sane.roles.ac = true;
   sane.roles.build-machine.enable = true;
   sane.roles.build-machine.emulation = false;
   sane.zsh.showDeadlines = false;  # ~/knowledge doesn't always exist

hosts/common/default.nix

@@ -6,7 +6,6 @@
     ./fs.nix
     ./hardware.nix
     ./home
-    ./i2p.nix
     ./ids.nix
     ./machine-id.nix
     ./net.nix

hosts/common/i2p.nix

@@ -1,4 +0,0 @@
-{ ... }:
-{
-  services.i2p.enable = true;
-}

hosts/modules/roles/ac.nix

@@ -0,0 +1,16 @@
+{ config, lib, ... }:
+{
+  options.sane.roles.ac = with lib; mkOption {
+    type = types.bool;
+    default = false;
+    description = ''
+      services which you probably only want to use with AC power.
+      specifically because they drain resources like power or bandwidth.
+    '';
+  };
+
+  config = lib.mkIf config.sane.roles.ac {
+    sane.yggdrasil.enable = true;
+    services.i2p.enable = true;
+  };
+}

hosts/modules/roles/default.nix

@@ -1,6 +1,7 @@
 { ... }:
 {
   imports = [
+    ./ac.nix
     ./build-machine.nix
     ./client
     ./dev-machine.nix