Adds support for /etc/hosts on darwin

common/hosts/ubc

@@ -0,0 +1,7 @@
+gambier.students.cs.ubc.ca gambierubc
+pender.students.cs.ubc.ca  penderubc
+thetis.students.cs.ubc.ca  thetisubc
+anvil.students.cs.ubc.ca   anvilubc
+valdes.students.cs.ubc.ca  valdesubc
+bowen.students.cs.ubc.ca   bowenubc
+remote.students.cs.ubc.ca  ubc

common/hosts/zerotier

@@ -0,0 +1,2 @@
+10.1.2.16  zeus
+10.1.2.175 nixbox

common/system.nix

@@ -18,6 +18,11 @@
     SHELL = "${pkgs.zsh}/bin/zsh";
   };
 
+  networking.hostFiles = [
+    ./hosts/ubc
+    ./hosts/zerotier
+  ];
+
   nix = {
     package = pkgs.nix;
     settings.experimental-features = ["nix-command" "flakes" "repl-flake"];

nixos/hosts/zeus.nix

@@ -3,6 +3,7 @@
     ../../common/system.nix
     ../modules/nix/link-inputs.nix
     ../modules/nix/use-flake-pkgs.nix
+    ../modules/darwin/hosts.nix
   ];
 
   nix = {
@@ -12,6 +13,9 @@
     linux-builder.enable = true;
   };
 
+  networking.hostName = "zeus";
+  networking.computerName = "Zeus";
+
   environment.etc."nix/user-sandbox.sb".text = ''
     (version 1)
     (allow default)

nixos/modules/darwin/hosts.nix

@@ -0,0 +1,82 @@
+# copied from https://github.com/NixOS/nixpkgs/blob/85f1ba3e51676fa8cc604a3d863d729026a6b8eb/nixos/modules/config/networking.nix
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}: let
+  inherit (lib) types mkBefore;
+  inherit (lib.lists) optional;
+  inherit (lib.options) literalExpression literalMD;
+  inherit (lib.attrsets) attrNames filterAttrs;
+  inherit (lib.strings) concatStringsSep concatMapStrings;
+  cfg = config.networking;
+in {
+  options = {
+    networking.hosts = lib.mkOption {
+      type = types.attrsOf (types.listOf types.str);
+      example = literalExpression ''
+        {
+          "127.0.0.1" = [ "foo.bar.baz" ];
+          "192.168.0.2" = [ "fileserver.local" "nameserver.local" ];
+        };
+      '';
+      description = lib.mdDoc ''
+        Locally defined maps of hostnames to IP addresses.
+      '';
+    };
+
+    networking.hostFiles = lib.mkOption {
+      type = types.listOf types.path;
+      defaultText = literalMD "Hosts from {option}`networking.hosts` and {option}`networking.extraHosts`";
+      example = literalExpression ''[ "''${pkgs.my-blocklist-package}/share/my-blocklist/hosts" ]'';
+      description = lib.mdDoc ''
+        Files that should be concatenated together to form {file}`/etc/hosts`.
+      '';
+    };
+
+    networking.extraHosts = lib.mkOption {
+      type = types.lines;
+      default = "";
+      example = "192.168.0.1 lanlocalhost";
+      description = lib.mdDoc ''
+        Additional verbatim entries to be appended to {file}`/etc/hosts`.
+        For adding hosts from derivation results, use {option}`networking.hostFiles` instead.
+      '';
+    };
+  };
+
+  config = {
+    networking.hosts = let
+      hostnames =
+        optional (cfg.hostName != "") cfg.hostName; # Then the hostname (without the domain)
+    in {
+      "127.0.0.1" = hostnames;
+      "::1" = hostnames;
+    };
+
+    networking.hostFiles = let
+      # Note: localhostHosts has to appear first in /etc/hosts so that 127.0.0.1
+      # resolves back to "localhost" (as some applications assume) instead of
+      # the FQDN! By default "networking.hosts" also contains entries for the
+      # FQDN so that e.g. "hostname -f" works correctly.
+      localhostHosts = pkgs.writeText "localhost-hosts" ''
+        127.0.0.1       localhost
+        ::1             localhost
+        255.255.255.255 broadcasthost
+      '';
+      stringHosts = let
+        oneToString = set: ip: ip + " " + concatStringsSep " " set.${ip} + "\n";
+        allToString = set: concatMapStrings (oneToString set) (attrNames set);
+      in
+        pkgs.writeText "string-hosts" (allToString (filterAttrs (_: v: v != []) cfg.hosts));
+      extraHosts = pkgs.writeText "extra-hosts" cfg.extraHosts;
+    in
+      mkBefore [localhostHosts stringHosts extraHosts];
+
+    environment.etc.hosts = {
+      copy = true;
+      source = pkgs.concatText "hosts" cfg.hostFiles;
+    };
+  };
+}