{ config, lib, nodes, ... }:
{
  nix = {
    # Machines to build derviations on
    buildMachines = with nodes; [
      {
        hostName = "midas";
        system = midas.config.nixpkgs.hostPlatform.system;
        supportedFeatures = midas.config.nix.settings.system-features;
        publicHostKey = "c3NoLWVkMjU1MTkgQUFBQUMzTnphQzFsWkRJMU5URTVBQUFBSUZjRk12cng5L2lVWjFtRXViZitRRjFpM0xOVHhGaGFVLzF6RlNqZG8wa0sgcm9vdEBraXR0eQo=";
        protocol = "ssh-ng";
        sshKey = "/root/.ssh/buildkey";
        maxJobs = 8;
      }
      {
        hostName = "kitty";
        system = kitty.config.nixpkgs.hostPlatform.system;
        supportedFeatures = kitty.config.nix.settings.system-features;
        publicHostKey = "c3NoLWVkMjU1MTkgQUFBQUMzTnphQzFsWkRJMU5URTVBQUFBSUlyR21zeWE1RFhLdVhPNmpOalVscllIcWs0OUtMenhNLzYwR1h0TFJMckwgcm9vdEBraXR0eQo=";
        protocol = "ssh-ng";
        sshKey = "/root/.ssh/buildkey";
        maxJobs = 8;
      }
      {
        hostName = "detritus";
        system = detritus.config.nixpkgs.hostPlatform.system;
        supportedFeatures = detritus.config.nix.settings.system-features;
        publicHostKey = "c3NoLWVkMjU1MTkgQUFBQUMzTnphQzFsWkRJMU5URTVBQUFBSU4rR3ZMcm80RFZtbHZtWGNhc1UxZ2N0SVg5cWN0N21adEVscEI3MzVBb0wgcm9vdEBkZXRyaXR1cwo=";
        protocol = "ssh-ng";
        sshKey = "/root/.ssh/buildkey";
        maxJobs = 8;
      }
      {
        hostName = "elder";
        system = elder.config.nixpkgs.hostPlatform.system;
        supportedFeatures = elder.config.nix.settings.system-features;
        publicHostKey = "c3NoLWVkMjU1MTkgQUFBQUMzTnphQzFsWkRJMU5URTVBQUFBSUZqbUo2Ymt1TzU3Z3A2R1pERWZSMU83a3JkZjV3aXFyT0JDNXB6VERsOTEgcm9vdEBlbGRlcgo=";
        protocol = "ssh-ng";
        sshKey = "/root/.ssh/buildkey";
        maxJobs = 8;
      }
      {
        hostName = "prophet";
        system = prophet.config.nixpkgs.hostPlatform.system;
        supportedFeatures = prophet.config.nix.settings.system-features;
        publicHostKey = "c3NoLWVkMjU1MTkgQUFBQUMzTnphQzFsWkRJMU5URTVBQUFBSUNycDNZL1gyQlJVRU54KzBHTVRtQjFWREE2U2l3a0dnZEpNSFNkTU1lcE0gcm9vdEBwcm9waGV0Cg==";
        protocol = "ssh-ng";
        sshKey = "/root/.ssh/buildkey";
        maxJobs = 8;
      }
    ];

    # Enable distributed builds
    distributedBuilds = true;

    settings = {
      # Serve derivations more efficiently, using substituters
      substituters = [
        "ssh-ng://midas"
        "ssh-ng://kitty"
        "ssh-ng://detritus"
        "ssh-ng://elder"
        "ssh-ng://prophet"
      ];
      trusted-public-keys = [
        "midas:YpyfZyVlTlPjzcVsYBnN13EgeK95y1WXxm9h1V8tM7E="
        "kitty:QLl9Do4v+2Q/fapozUGoXIKJul+Zck3yAsmAo9Lg4is="
        "detritus:xtQVaIyDIBWS+EAU11dBsW9BUMT7aAZRPjKp3Udgdvc="
        "elder:U+zIEvxNeqOxAWbZyrJzDNrJF1GJdcrLEYbIqmKGd7U="
        "prophet:NPlWmuX1vz95uUIddQXlwrkmdSMZW1U27CdEY812brg="
      ];

      # Settings to sign the derivations and allow building
      max-jobs = if builtins.elem "server" config.system.nixos.tags then "auto" else 0;
      secret-key-files = "/var/lib/nixos/cache-priv-key.pem";
      trusted-users = [ "root" ];
    };
  };
}