{ nglib, nixpkgs }:
{
  postgresql = nglib.makeSystem {
    system = "x86_64-linux";
    name = "nixng-hydra-postgresql";
    inherit nixpkgs;
    config = { pkgs, config, ... }:
      {
        config = {
          dumb-init = {
            enable = true;
            type.services = {};
          };
          services.postgresql = {
            enable = true;
            package = pkgs.postgresql_12;

            initialScript = "/secrets/init.sql";
            enableTCPIP = true;

            authentication = "host  all all all          md5";

            ensureDatabases = [ "hydra" ];
            ensureExtensions = {
              "pg_trgm" = [ "hydra" ];
            };
            ensureUsers = [
              { name = "hydra"; ensurePermissions = {
                  "DATABASE \"hydra\"" = "ALL PRIVILEGES";
                };
              }
            ];
          };
        };
      };
  };

  hydra = nglib.makeSystem {
    system = "x86_64-linux";
    name = "nixng-hydra";
    inherit nixpkgs;
    config = { pkgs, config, lib, nglib, ... }:
      {
        config = {
          dumb-init = {
            enable = true;
            type.services = {};
          };
          nix = {
            package = pkgs.nixUnstable;
            loadNixDb = true;
            persistNix = "/nix-persist";
            config = {
              experimental-features = [ "nix-command" "flakes" ];
              sandbox = true;
              trusted-public-keys = [ "cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=" ];
              substituters = [ "https://cache.nixos.org/" ];
              ignored-acls = [ "system.nfs4_acl" ];
              allowed-uris =
                [ "https://gitea.redalder.org"
                  "https://github.com"
                  "https://gitlab.com"
                  "https://git.sr.ht"
                  "https://raw.githubusercontent.com"
                  "https://media.forgecdn.net"
                ];

              builders-use-substitutes = true;
              builders = "@/etc/nix/machines";
            };
          };
          services.hydra = {
            enable = true;
            hydraURL = "https://hydra.redalder.org";
            notificationSender = "hydra@redalder.org";
            useSubstitutes = true;
            adjustNiceness = true;

            minimumDiskFree = 200;
            minimumDiskFreeEvaluator = 100;

            dbiFile = "/local/dbi";
          };
          services.socklog = {
            enable = true;
            unix = "/dev/log";
          };

          init.services.pgpass = {
            script = pkgs.writeShellScript "pgpass" ''
              ln -nsf /secrets/pgpass /var/lib/hydra/pgpass
              ln -nsf /secrets/pgpass-www /var/lib/hydra/pgpass-www
              ln -nsf /secrets/pgpass-queue-runner /var/lib/hydra/pgpass-queue-runner

              chown hydra:hydra /secrets/pgpass
              chown hydra-www:hydra /secrets/pgpass-www
              chown hydra-queue-runner:hydra /secrets/pgpass-queue-runner
              sv down pgpass
            '';
            enabled = true;
          };

          init.services.nix-daemon.environment.PATH = with pkgs;
            lib.makeBinPath [ utillinux runit busybox openssh gzip ];

          system.activation =
            { nix-machines =
                let
                  machines = pkgs.writeText "machines"
                    ''
                      eu.nixbuild.net x86_64-linux - 100 5 benchmark,big-parallel
                    '';
                in
                  nglib.dag.dagEntryAnywhere
                    ''
                      export PATH=${pkgs.busybox}/bin

                      mkdir -p /etc/nix
                      ln -s ${machines} /etc/nix/machines
                    '';
              ssh =
                let
                  ssh_config = pkgs.writeText "ssh_config"
                    ''
                      Host eu.nixbuild.net
                        PubkeyAcceptedKeyTypes ssh-ed25519
                        IdentityFile /ssh-key
                    '';
                  ssh_known_hosts = pkgs.writeText "ssh_known_hosts"
                    ''
                      eu.nixbuild.net ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIPIQCZc54poJ8vqawd8TraNryQeJnvH1eLpIDgbiqymM
                    '';
                in
                  nglib.dag.dagEntryAnywhere
                    ''
                      export PATH=${pkgs.busybox}/bin

                      mkdir -p /etc/ssh
                      ln -s ${ssh_config} /etc/ssh/ssh_config
                      ln -s ${ssh_known_hosts} /etc/ssh/ssh_known_hosts
                    '';
              ssh-key =
                  nglib.dag.dagEntryAfter ["users"]
                    ''
                      export PATH=${pkgs.busybox}/bin

                      cp /secrets/ssh-key /ssh-key
                      chmod 600 /ssh-key
                      chown hydra-queue-runner:root /ssh-key
                    '';
            };
        };
      };
  };
}