Set up hydra as a remote build machine.

nix/configuration/hosts/hydra/default.nix

@@ -18,10 +18,43 @@
   ];
 
   config = {
-    # Generate with `head -c4 /dev/urandom | od -A none -t x4`
-    networking.hostId = "6fbf418b";
+    networking =
+      let
+        interface = "enp0s2";
+      in
+      {
+        # Generate with `head -c4 /dev/urandom | od -A none -t x4`
+        hostId = "6fbf418b";
 
-    networking.hostName = "hydra"; # Define your hostname.
+        hostName = "hydra"; # Define your hostname.
+
+        interfaces = {
+          "${interface}" = {
+            ipv4.addresses = [
+              {
+                address = "10.215.1.219";
+                prefixLength = 24;
+              }
+            ];
+
+            ipv6.addresses = [
+              {
+                address = "2620:11f:7001:7:ffff:ffff:0ad7:01db";
+                prefixLength = 64;
+              }
+            ];
+          };
+        };
+        defaultGateway = "10.215.1.1";
+        defaultGateway6 = {
+          # address = "2620:11f:7001:7::1";
+          address = "2620:11f:7001:7:ffff:ffff:0ad7:0101";
+          inherit interface;
+        };
+
+        dhcpcd.enable = lib.mkForce false;
+        useDHCP = lib.mkForce false;
+      };
 
     time.timeZone = "America/New_York";
     i18n.defaultLocale = "en_US.UTF-8";
@@ -63,13 +96,42 @@
 
     environment.systemPackages = with pkgs; [
       htop
+      git # for building on hydra
+      tmux # for building on hydra
+      nix-output-monitor # for building on hydra
     ];
 
     # nix.sshServe.enable = true;
     # nix.sshServe.keys = [ "ssh-dss AAAAB3NzaC1k... bob@example.org" ];
 
+    # Override garbage collection to keep things longer
+    # Automatic garbage collection
+    nix.gc = lib.mkForce {
+      automatic = true;
+      persistent = true;
+      dates = "weekly";
+      # randomizedDelaySec = "14m";
+      options = "--delete-older-than 60d";
+    };
+
+    # The default limit of files is 1024 which is too low for some nix builds.
+    #
+    # Check with `ulimit -n`
+    security.pam.loginLimits = [
+      {
+        domain = "*";
+        item = "nofile";
+        type = "-";
+        value = "8192";
+      }
+    ];
+
+    # systemd.user.extraConfig = "DefaultLimitNOFILE=8192";
+    # systemd.services."user@11400".serviceConfig.LimitNOFILE = "8192";
+
     me.build_in_ram.enable = true;
     me.dont_use_substituters.enable = true;
+    me.hydra.enable = true;
     me.minimal_base.enable = true;
     me.nix_worker.enable = true;
   };

nix/configuration/hosts/hydra/vm_disk.nix

@@ -26,7 +26,7 @@
         neededForBoot = true;
       };
 
-      # "/.disk" = lib.mkForce {
+      # "/.persist" = lib.mkForce {
       #   device = "bind9p";
       #   fsType = "9p";
       #   options = [
@@ -35,6 +35,10 @@
       #     "version=9p2000.L"
       #     "cache=mmap"
       #     "msize=512000"
+      #     "uname=root"
+      #     "dfltuid=0"
+      #     "dfltgid=0"
+      #     "nodevmap"
       #     # "noauto"
       #     # "x-systemd.automount"
       #   ];
@@ -67,25 +71,25 @@
         neededForBoot = true;
       };
 
-      "/nix/store" = lib.mkForce {
-        overlay = {
-          lowerdir = [ "/nix/.ro-store" ];
-          upperdir = "/.disk/persist/store";
-          workdir = "/.disk/state/work";
-        };
-        # fsType = "overlay";
-        # device = "overlay";
-        # options = [
-        #   "lowerdir=/nix/.ro-store"
-        #   "upperdir=/.disk/persist/store"
-        #   "workdir=/.disk/state/work"
-        # ];
-        depends = [
-          "/nix/.ro-store"
-          "/.disk/persist/store"
-          "/.disk/state/work"
-        ];
-      };
+      # "/nix/store" = lib.mkForce {
+      #   overlay = {
+      #     lowerdir = [ "/nix/.ro-store" ];
+      #     upperdir = "/.disk/persist/store";
+      #     workdir = "/.disk/state/work";
+      #   };
+      #   # fsType = "overlay";
+      #   # device = "overlay";
+      #   # options = [
+      #   #   "lowerdir=/nix/.ro-store"
+      #   #   "upperdir=/.disk/persist/store"
+      #   #   "workdir=/.disk/state/work"
+      #   # ];
+      #   depends = [
+      #     "/nix/.ro-store"
+      #     "/.disk/persist/store"
+      #     "/.disk/state/work"
+      #   ];
+      # };
     };
   };
 }

nix/configuration/hosts/odo/SELF_BUILD

@@ -5,6 +5,12 @@ IFS=$'\n\t'
 DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 
 : "${JOBS:="1"}"
+: "${NOM:="true"}"
 
 for f in /persist/manual/manual_add_to_store/*; do nix-store --add-fixed sha256 "$f"; done
-nixos-rebuild build --show-trace --sudo --max-jobs "$JOBS" --flake "$DIR/../../#odo" --log-format internal-json -v "${@}" |& nom --json
+
+if [ "$NOM" = "true" ]; then
+    nixos-rebuild build --show-trace --sudo --max-jobs "$JOBS" --flake "$DIR/../../#odo" --log-format internal-json -v "${@}" |& nom --json
+else
+    nixos-rebuild build --show-trace --sudo --max-jobs "$JOBS" --flake "$DIR/../../#odo" -v "${@}"
+fi

nix/configuration/hosts/odo/distributed_build.nix

@@ -4,6 +4,12 @@
   config = {
     me.distributed_build.enable = true;
     me.distributed_build.machines.quark = {
+      enable = false;
+      additional_config = {
+        speedFactor = 2;
+      };
+    };
+    me.distributed_build.machines.hydra = {
       enable = true;
       additional_config = {
         speedFactor = 2;

nix/configuration/hosts/odowork/distributed_build.nix

@@ -4,6 +4,12 @@
   config = {
     me.distributed_build.enable = true;
     me.distributed_build.machines.quark = {
+      enable = false;
+      additional_config = {
+        speedFactor = 2;
+      };
+    };
+    me.distributed_build.machines.hydra = {
       enable = true;
       additional_config = {
         speedFactor = 2;

nix/configuration/hosts/quark/distributed_build.nix

@@ -3,5 +3,11 @@
 
   config = {
     me.distributed_build.enable = true;
+    me.distributed_build.machines.hydra = {
+      enable = true;
+      additional_config = {
+        speedFactor = 2;
+      };
+    };
   };
 }