{
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
    nixpkgs-krypton.url = "github:NixOS/nixpkgs/nixos-unstable";
    nixpkgs-schule.url = "github:NixOS/nixpkgs/nixos-unstable";
    nixos-hardware.url = "github:NixOS/nixos-hardware/master";
    agenix = {
      url = "github:ryantm/agenix";
      inputs.nixpkgs.follows = "nixpkgs";
    };
    chaosevents = {
      url = "git+https://git.clerie.de/clerie/chaosevents.git";
      inputs.nixpkgs.follows = "nixpkgs";
    };
    fernglas = {
      url = "github:wobcom/fernglas";
      inputs.nixpkgs.follows = "nixpkgs";
    };
    fieldpoc.url = "git+https://git.clerie.de/clerie/fieldpoc.git";
    nixos-exporter = {
      url = "git+https://git.clerie.de/clerie/nixos-exporter.git";
      inputs.nixpkgs.follows = "nixpkgs";
    };
    solid-xmpp-alarm = {
      url = "git+https://git.clerie.de/clerie/solid-xmpp-alarm.git";
      inputs.nixpkgs.follows = "nixpkgs";
    };
  };
  outputs = { self, agenix, nixpkgs, nixos-hardware, chaosevents, fernglas, nixos-exporter, solid-xmpp-alarm, ... }@inputs: let
    helper = (import ./lib/flake-helper.nix) inputs;
  in {
    clerie.hosts = {
      aluminium = {
        name = "aluminium";
        group = "event";
      };
      astatine = {
        name = "astatine";
        group = "event";
      };
      backup-4 = { name = "backup-4"; };
      beryllium = {
        name = "beryllium";
        group = "event";
      };
      carbon = { name = "carbon"; };
      clerie-backup = { name = "clerie-backup"; };
      dn42-il-gw1 = { name = "dn42-il-gw1"; };
      dn42-il-gw5 = { name = "dn42-il-gw5"; };
      dn42-il-gw6 = { name = "dn42-il-gw6"; };
      dn42-ildix-clerie = { name = "dn42-ildix-clerie"; };
      dn42-ildix-service = { name = "dn42-ildix-service"; };
      gatekeeper = { name = "gatekeeper"; };
      hydra-1 = { name = "hydra-1"; };
      hydra-2 = { name = "hydra-2"; };
      krypton = {
        name = "krypton";
        modules = [
          nixos-hardware.nixosModules.lenovo-thinkpad-x270
        ];
      };
      mail-2 = { name = "mail-2"; };
      minecraft-2 = { name = "minecraft-2"; };
      monitoring-3 = { name = "monitoring-3"; };
      nonat = { name = "nonat"; };
      osmium = { name = "osmium"; };
      palladium = { name = "palladium"; };
      porter = { name = "porter"; };
      schule = { name = "schule"; };
      storage-2 = { name = "storage-2"; };
      web-2 = { name = "web-2"; };
      zinc = { name = "zinc"; };
      # nixfiles-auto-install: add new host above
      _iso = { name = "_iso"; };
    };

    nixosConfigurations = helper.mapToNixosConfigurations self.clerie.hosts;

    colmena = {
      meta = {
        nixpkgs = import nixpkgs {
          system = "x86_64-linux";
        };
      };
    } // helper.mapToColmenaHosts self.nixosConfigurations;

    packages.x86_64-linux = let
      pkgs = import nixpkgs {
        overlays = [
          (import ./pkgs/overlay.nix)
          (_: _: {
            inherit (agenix.packages."x86_64-linux")
              agenix;
            inherit (chaosevents.packages."x86_64-linux")
              chaosevents;
           })
        ];
        system = "x86_64-linux";
      };
    in {
      inherit (pkgs)
        anycast_healthchecker
        flask-excel
        iot-data
        nixfiles-add-secret
        nixfiles-auto-install
        nixfiles-generate-backup-secrets
        nixfiles-generate-config
        nixfiles-updated-inputs
        nixfiles-update-ssh-host-keys
        pyexcel-xlsx
        pyexcel-webio
        update-from-hydra
        uptimestatus
        wetter;
    };

    hydraJobs = {
      inherit (self)
        packages;
      nixosConfigurations = helper.buildHosts self.nixosConfigurations;
      iso = self.nixosConfigurations._iso.config.system.build.isoImage;
    };

    nixConfig = {
      extra-substituters = [
        "https://nix-cache.clerie.de"
      ];
      extra-trusted-public-keys = [
        "nix-cache.clerie.de:bAt1GJTS9BOTcXFWj3nURrSlcjqikCev9yDvqArMP5g="
      ];
    };
  };
}