{ config, lib, ... }: {
  nix.buildMachines = [
    {
      hostName = "localhost";
      protocol = null;
      maxJobs = 0;
      speedFactor = 0;
      systems = [ "x86_64-linux" ];
      supportedFeatures = [ "nixos-test" "benchmark" "big-parallel" "kvm" ];
    }
    {
      hostName = "integra.kyouma.net";
      sshUser = "nix-ssh";
      maxJobs = 2;
      speedFactor = 4;
      systems = [ "aarch64-linux" ];
      supportedFeatures = [ "nixos-test" "benchmark" "big-parallel" "kvm" ];
      sshKey = config.sops.secrets."services/hydra/id_ed25519_hydra".path;
    }
  ] ++ lib.forEach [ "03" "04" ] (num: {
      hostName = "build-worker-${num}.nyantec.com";
      sshUser = "nix-ssh";
      maxJobs = 4;
      speedFactor = 18;
      systems = [ "x86_64-linux" "riscv64-linux" ];
      supportedFeatures = [ "nixos-test" "benchmark" "big-parallel" "kvm" "gccarch-x86-64" "gccarch-x86-64-v2" "gccarch-x86-64-v3" ];
      sshKey = config.sops.secrets."services/hydra/id_ed25519_hydra".path;
    }
  ) ++ lib.forEach [ "01" "02" "05" "06" ] (num: {
      hostName = "build-worker-${num}";
      sshUser = "root";
      maxJobs = 4;
      speedFactor = 20;
      systems = [ "x86_64-linux" ];
      supportedFeatures = [ "nixos-test" "benchmark" "big-parallel" "gccarch-x86-64" "gccarch-x86-64-v2" "gccarch-x86-64-v3" ];
      sshKey = config.sops.secrets."services/hydra/id_ed25519_hydra".path;
  });
  nix.settings = {
    allowed-uris = [
      "github:"
      "git+https://"
      "git+ssh://"
      "https://"
    ];
  };
  programs.ssh = {
    knownHosts = {
      "build-worker-03.nyantec.com".publicKey = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIEGqTY74c5g15DSNPNM2Wdr5jAwS7BFgX1XRnhtGOnJc";
      "build-worker-04.nyantec.com".publicKey = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAICOq+5I+nlAN2lJoOtoXrYEDuZ/TMPMa43pIlablYigK";
      "integra.kyouma.net".publicKey = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIIBwEQiSfaDrUAwgul4mktusBPcIVxI4pLNDh9DPopVU";
      "localhost".publicKey = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIPNVavo3YHVsrYwXRVISu7kDoknn+5inFGySn4azlB8P";
      "[build-worker-kyoumanet.fly.dev]:2201".publicKey = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIDL2M97UBHg9aUfjDUxzmzg1r0ga0m3/stummBVwuEAB";
      "[build-worker-kyoumanet.fly.dev]:2202".publicKey = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIOTwVKL0P0chPM2Gz23rbT94844+w1CGJdCaZdzfjThz";
      "[build-worker-kyoumanet.fly.dev]:2203".publicKey = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIAjy2eZGJQeAYy0+fLgW9jiS0jVY2LInY0NDMnzCvvKp";
      "[build-worker-kyoumanet.fly.dev]:2204".publicKey = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIN72OyD9LYy4hq0WZ7ie5RPV+G54UreEJiA/RubjGoe9";
    }; 
    extraConfig = ''
      Host build-worker-01
        Hostname build-worker-kyoumanet.fly.dev
        Port 2201
      Host build-worker-02
        Hostname build-worker-kyoumanet.fly.dev
        Port 2202
      Host build-worker-05
        Hostname build-worker-kyoumanet.fly.dev
        Port 2203
      Host build-worker-06
        Hostname build-worker-kyoumanet.fly.dev
        Port 2204
    '';
  };
}