diff --git a/.gitignore b/.gitignore
index a806510..84e7193 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,4 +2,4 @@
 # Ignore build outputs from performing a nix-build or `nix build` command
 result
 result-*
-
+.pre-commit-config.yaml
diff --git a/README.md b/README.md
index 2c6a796..c9d9672 100644
--- a/README.md
+++ b/README.md
@@ -146,8 +146,7 @@ machine. The only technically required file in there is `configuration.nix`. So
 
 A good skeleton is probably:
 ```
-flake-inputs:
-{config, pkgs, lib, ... }: {
+{config, pkgs, lib, flake-inputs, ... }: {
 
 imports = [
   ./hardware-configuration.nix
@@ -278,3 +277,29 @@ something like this:
 {lib, pkgs, config, ...} :
 <module code >
 ```
+
+# Contributing
+
+Like with all FS projects, you are welcome to contribute. Work is done usually by the person that is most annoyed
+by the circumstances or by the person that didn't run fast enough. So we are happy if we get help. That doesn't
+mean that we don't need to have some level of quality, people after us needs to work with it. It is live infrastructure
+and downtime hurts someone (and in the wrong moment even really bad (Matheball ticket sales for example).
+
+So here are some Guidelines.
+
+## Coding style and linting.
+If you run `nix check` there are automated checks in place, please make sure to pass them.
+There is also a code autoformatter (`alejandra`) incorporated into those. You can also install
+them into your local git repository as pre-commit hooks, and setting up a shell that has
+even more tooling by running `nix develop`. That will give you a bash in which you can run
+all the checks manually `pre-commit run -a`. This will also run the autoformatter.
+
+## Process for submitting changes
+
+1. If it is something bigger, please open an issue first describing what and why you want to do something.
+   If it is just something small, skip this step.
+2. Fork the repo and implement your changes in a branch on your fork. Afterwards open a pull request (possibly mentioning the issue).
+   Against the main branch.
+   - Your branch should be based on an up to date version of main, if it is not consider rebasing.
+3. You will need to find someone with the proper rights to approve of your changes, but most of the time there will be request
+   for changes first.
diff --git a/flake-module.nix b/flake-module.nix
index 2220d58..8584c3d 100644
--- a/flake-module.nix
+++ b/flake-module.nix
@@ -1,28 +1,60 @@
-{inputs, ...}:
-{
+{inputs, ...}: {
   # debug = true;
   # We only define machines config in this flake yet, so we only include
   # the module that builds these. This file might get fuller, if we need to
   # build our own packages, that are not flakes.
-  imports = [ ./nixos/flake-module.nix
-        # To import a flake module
-        # 1. Add foo to inputs
-        # 2. Add foo as a parameter to the outputs function
-        # 3. Add here: foo.flakeModule
-
+  imports = [
+    ./nixos/flake-module.nix
+    inputs.pre-commit-hooks.flakeModule
+    # To import a flake module
+    # 1. Add foo to inputs
+    # 2. Add foo as a parameter to the outputs function
+    # 3. Add here: foo.flakeModule
   ];
-  systems = [ "x86_64-linux"];
-#  perSystem = { config, self', inputs', pkgs, system, ... }: {
-  # Per-system attributes can be defined here. The self' and inputs'
-  # module parameters provide easy access to attributes of the same
-  # system.
+  systems = ["x86_64-linux"];
+  perSystem = {
+    config,
+    inputs',
+    pkgs,
+    ...
+  }: {
+    devShells.default = config.pre-commit.devShell;
+
+    pre-commit = let
+      generatedFiles = [
+        "hardware-configuration\\.nix"
+      ];
+    in {
+      check.enable = true;
+      pkgs = inputs'.nixpkgs.legacyPackages;
+      settings = {
+        # for some reason statix takes it config differently than all the other hooks.
+        settings.statix = {
+          format = "stderr";
+          ignore = generatedFiles;
+        };
+        hooks = {
+          nil.enable = true;
+          statix.enable = true;
+          deadnix = {
+            enable = true;
+            excludes = generatedFiles;
+          };
+          alejandra.enable = true;
+        };
+      };
+    };
+
+    # Per-system attributes can be defined here. The self' and inputs'
+    # module parameters provide easy access to attributes of the same
+    # system.
+  };
 
   # Equivalent to  inputs'.nixpkgs.legacyPackages.hello;
-#  };
-#      flake = {
-        # The usual flake attributes can be defined here, including system-
-        # agnostic ones like nixosModule and system-enumerating ones, although
-        # those are more easily expressed in perSystem.
+  #      flake = {
+  # The usual flake attributes can be defined here, including system-
+  # agnostic ones like nixosModule and system-enumerating ones, although
+  # those are more easily expressed in perSystem.
 
-#      };
+  #      };
 }
diff --git a/flake.nix b/flake.nix
index 0c61327..b4b5593 100644
--- a/flake.nix
+++ b/flake.nix
@@ -17,8 +17,17 @@
     impermanence = {
       url = "github:nix-community/impermanence";
     };
+    pre-commit-hooks = {
+      url = "github:cachix/pre-commit-hooks.nix";
+      inputs = {
+        flake-compat.follows = "";
+        gitignore.follows = "";
+        nixpkgs-stable.follows = "";
+        nixpkgs.follows = "";
+      };
+    };
   };
 
-  outputs = inputs@{ flake-parts, ... }:
-    flake-parts.lib.mkFlake { inherit inputs; } (import ./flake-module.nix);
+  outputs = inputs @ {flake-parts, ...}:
+    flake-parts.lib.mkFlake {inherit inputs;} (import ./flake-module.nix);
 }
diff --git a/nixos/flake-module.nix b/nixos/flake-module.nix
index 8c44964..bc1769b 100644
--- a/nixos/flake-module.nix
+++ b/nixos/flake-module.nix
@@ -1,20 +1,30 @@
 # copied and adopted from maralorns config
-
 # This automatically searches for nixos configs in ./machines/${name}/configuration.nix
 # and exposes them as outputs.nixosConfigurations.${name}
-{ withSystem, lib, inputs, ... }: {
+{
+  withSystem,
+  lib,
+  inputs,
+  ...
+}: {
   flake = {
-    nixosConfigurations = withSystem "x86_64-linux" ({ pkgs, ... }:
-    let
+    nixosConfigurations = withSystem "x86_64-linux" ({pkgs, ...}: let
       machines = builtins.attrNames (builtins.readDir ./machines);
-      makeSystem = name:
+      makeSystem = name: let
+        importedConfig = import (./. + "/machines/${name}/configuration.nix");
+        systemConfig =
+          if lib.isFunction importedConfig
+          then x: importedConfig (x // {flake-inputs = inputs;})
+          else importedConfig;
+      in
         pkgs.nixos {
           imports = [
-            (import (./. + "/machines/${name}/configuration.nix") inputs)
+            systemConfig
             inputs.sops-nix.nixosModules.sops
             inputs.impermanence.nixosModules.impermanence
           ];
         };
-    in lib.genAttrs machines makeSystem);
+    in
+      lib.genAttrs machines makeSystem);
   };
 }
diff --git a/nixos/machines/ghatanothoa/configuration.nix b/nixos/machines/ghatanothoa/configuration.nix
index 4e60e1b..3b4faa5 100644
--- a/nixos/machines/ghatanothoa/configuration.nix
+++ b/nixos/machines/ghatanothoa/configuration.nix
@@ -1,19 +1,17 @@
-flake-inputs:
-{config, pkgs, lib, ... }: {
-
-imports = [
-  ./hardware-configuration.nix
-  ../../modules/jitsi.nix
-  ../../roles
-  ./network.nix
-];
+{
+  imports = [
+    ./hardware-configuration.nix
+    ../../modules/jitsi.nix
+    ../../roles
+    ./network.nix
+  ];
 
   services.mathebau-jitsi = {
     enable = true;
     hostName = "meet.mathebau.de";
   };
 
-# System configuration here
+  # System configuration here
   networking.hostName = "ghatanothoa";
   system.stateVersion = "23.11";
 }
diff --git a/nixos/machines/ghatanothoa/hardware-configuration.nix b/nixos/machines/ghatanothoa/hardware-configuration.nix
index ad588c9..05a48b2 100644
--- a/nixos/machines/ghatanothoa/hardware-configuration.nix
+++ b/nixos/machines/ghatanothoa/hardware-configuration.nix
@@ -1,15 +1,15 @@
-{config, lib, pkgs, modulesPath, ...}: {
-  imports = [ ];
+{lib, ...}: {
+  imports = [];
 
   fileSystems."/" = {
     device = "gha-root";
     fsType = "tmpfs";
-    options = [ "size=1G" "mode=755" ];
+    options = ["size=1G" "mode=755"];
   };
   fileSystems."/persist" = {
     device = "/dev/disk/by-uuid/e0a160ef-7d46-4705-9152-a6b602898136";
     fsType = "btrfs";
-    options = [ "subvol=persist" ];
+    options = ["subvol=persist"];
     neededForBoot = true;
   };
   fileSystems."/boot" = {
@@ -19,11 +19,10 @@
   fileSystems."/nix" = {
     device = "/dev/disk/by-uuid/e0a160ef-7d46-4705-9152-a6b602898136";
     fsType = "btrfs";
-    options = [ "subvol=nix" ];
+    options = ["subvol=nix"];
   };
 
-  swapDevices =
-    [{ device = "/dev/disk/by-uuid/e6e3ba6b-c9f5-4960-b56d-f49760d76a4a"; }];
+  swapDevices = [{device = "/dev/disk/by-uuid/e6e3ba6b-c9f5-4960-b56d-f49760d76a4a";}];
 
   nix.settings.max-jobs = lib.mkDefault 4;
 
diff --git a/nixos/machines/ghatanothoa/network.nix b/nixos/machines/ghatanothoa/network.nix
index 7e26f79..2a1f4ae 100644
--- a/nixos/machines/ghatanothoa/network.nix
+++ b/nixos/machines/ghatanothoa/network.nix
@@ -1,15 +1,16 @@
 # We sohuld put that config somewhere in roles and give it a parameter or something,
 # everyone gets the same nameserver and the same prefixLength and address vs defaultGateway alsways
-# depend on the same thing 
+# depend on the same thing
 {
-  imports = [ ];
+  imports = [];
   networking = {
-    interfaces.enX0.ipv4.addresses = [ {
-      address = "192.168.0.25";
-      prefixLength = 16;
-    } ];
+    interfaces.enX0.ipv4.addresses = [
+      {
+        address = "192.168.0.25";
+        prefixLength = 16;
+      }
+    ];
     defaultGateway = "192.168.0.152";
     nameservers = ["130.83.2.22" "130.83.56.60" "130.83.22.60" "130.82.22.63"];
   };
 }
-
diff --git a/nixos/modules/impermanence.nix b/nixos/modules/impermanence.nix
index 267c9d1..f5df277 100644
--- a/nixos/modules/impermanence.nix
+++ b/nixos/modules/impermanence.nix
@@ -1,47 +1,47 @@
-{lib, config, ...} :
-
-let 
-  inherit (lib)
+{
+  lib,
+  config,
+  ...
+}: let
+  inherit
+    (lib)
     mkEnableOption
     mkIf
     mkOption
     types
     ;
   cfg = config.impermanence;
-in
+in {
+  imports = [];
 
-{
-imports = [ ];
-
-options.impermanence = {
-  enable = mkEnableOption "impermanence";
-  storagePath = mkOption {
-    type = types.path;
-    default = "/persist";
-    description = "The path where persistent data is stored";
+  options.impermanence = {
+    enable = mkEnableOption "impermanence";
+    storagePath = mkOption {
+      type = types.path;
+      default = "/persist";
+      description = "The path where persistent data is stored";
+    };
+    name = mkOption {
+      type = types.str;
+      default = "persist";
+      description = "the name of the persistent data store";
+    };
   };
-  name = mkOption {
-    type = types.str;
-    default = "persist";
-    description = "the name of the persistent data store";
-  };
-};
 
-config = mkIf cfg.enable {
-  environment.persistence.${cfg.name} = {
-    persistentStoragePath = cfg.storagePath;
-    directories = [
-      "/var/log"
-      "/var/lib/nixos"
-    ];
-    files = [
-      "/etc/ssh/ssh_host_ed25519_key"
-      "/etc/ssh/ssh_host_ed25519_key.pub"
-      "/etc/ssh/ssh_host_rsa_key"
-      "/etc/ssh/ssh_host_rsa_key.pub"
-    ];
+  config = mkIf cfg.enable {
+    environment.persistence.${cfg.name} = {
+      persistentStoragePath = cfg.storagePath;
+      directories = [
+        "/var/log"
+        "/var/lib/nixos"
+      ];
+      files = [
+        "/etc/ssh/ssh_host_ed25519_key"
+        "/etc/ssh/ssh_host_ed25519_key.pub"
+        "/etc/ssh/ssh_host_rsa_key"
+        "/etc/ssh/ssh_host_rsa_key.pub"
+      ];
+    };
+    environment.etc.machine-id.source = "${cfg.storagePath}/machine-id";
   };
-  environment.etc.machine-id.source = "${cfg.storagePath}/machine-id";
-};
-
 }
diff --git a/nixos/modules/jitsi.nix b/nixos/modules/jitsi.nix
index ca2a8a7..7af6662 100644
--- a/nixos/modules/jitsi.nix
+++ b/nixos/modules/jitsi.nix
@@ -1,16 +1,21 @@
-{pkgs, config, lib, modulesPath, ...}:
-let 
-  inherit (lib)
+{
+  config,
+  lib,
+  modulesPath,
+  ...
+}: let
+  inherit
+    (lib)
     mkIf
     mkEnableOption
     mkOption
-    head;
+    head
+    ;
   inherit (lib.types) str;
   cfg = config.services.mathebau-jitsi;
-in
-{
+in {
   imports = [(modulesPath + "/services/web-apps/jitsi-meet.nix")];
-  
+
   options.services.mathebau-jitsi = {
     enable = mkEnableOption "mathebau jitsi service";
     hostName = mkOption {
@@ -23,18 +28,25 @@ in
   };
 
   config = mkIf cfg.enable {
-    services.jitsi-meet = {
-      enable = true;
-      hostName = cfg.hostName;
-      config = {
-        defaultLang = "de";
+    services = {
+      jitsi-meet = {
+        enable = true;
+        config = {
+          defaultLang = "de";
+        };
+        inherit (cfg) hostName;
       };
-    };
-    services.jitsi-videobridge = {
-      openFirewall = true;
-      nat = {
-        publicAddress = "130.83.2.184";
-        localAddress = cfg.localAddress;
+      jitsi-videobridge = {
+        openFirewall = true;
+        nat = {
+          publicAddress = "130.83.2.184";
+          inherit (cfg) localAddress;
+        };
+      };
+      #We are behind a reverse proxy that handles TLS
+      nginx.virtualHosts."${cfg.hostName}" = {
+        enableACME = false;
+        forceSSL = false;
       };
     };
     environment.persistence.${config.impermanence.name} = {
@@ -43,13 +55,7 @@ in
         "/var/lib/prosody"
       ];
     };
-  #We are behind a reverse proxy that handles TLS
-    services.nginx.virtualHosts."${cfg.hostName}" = {
-      enableACME = false;
-      forceSSL = false;
-    };
-
-  #The network ports for HTTP(S) are not opened automatically
-    networking.firewall.allowedTCPPorts = [ 80 443 ];
+    #The network ports for HTTP(S) are not opened automatically
+    networking.firewall.allowedTCPPorts = [80 443];
   };
 }
diff --git a/nixos/roles/admins.nix b/nixos/roles/admins.nix
index 32478bf..3215ccc 100644
--- a/nixos/roles/admins.nix
+++ b/nixos/roles/admins.nix
@@ -1,37 +1,34 @@
-{lib, ...} :
-with lib;
-
-let
+{lib, ...}:
+with lib; let
   admins = {
     nerf = {
-      hashedPassword =
-        "$y$j9T$SJcjUIcs3JYuM5oyxfEQa/$tUBQT07FK4cb9xm.A6ZKVnFIPNOYMOKC6Dt6hadCuJ7";
-        keys = [
-          "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIEdA4LpEGUUmN8esFyrNZXFb2GiBID9/S6zzhcnofQuP nerf@nerflap2"
-        ];
+      hashedPassword = "$y$j9T$SJcjUIcs3JYuM5oyxfEQa/$tUBQT07FK4cb9xm.A6ZKVnFIPNOYMOKC6Dt6hadCuJ7";
+      keys = [
+        "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIEdA4LpEGUUmN8esFyrNZXFb2GiBID9/S6zzhcnofQuP nerf@nerflap2"
+      ];
     };
     gonne = {
-      hashedPassword =
-        "$6$EtGpHEcFkOi0yUWp$slXf0CvIUrhdqaoCrQ5YwtYu2IVuE1RGGst4fnDPRLWVm.lYx0ruvSAF2/vw/sLbW37ORJjlb0NHQ.kSG7cVY/";
-        keys = [
-          "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIFopCUadohY3wg9AoEup9TDRDMyEPSLsQoCnN4lsKCrr gonne@mathebau.de NixOS"
-        ];
+      hashedPassword = "$6$EtGpHEcFkOi0yUWp$slXf0CvIUrhdqaoCrQ5YwtYu2IVuE1RGGst4fnDPRLWVm.lYx0ruvSAF2/vw/sLbW37ORJjlb0NHQ.kSG7cVY/";
+      keys = [
+        "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIFopCUadohY3wg9AoEup9TDRDMyEPSLsQoCnN4lsKCrr gonne@mathebau.de NixOS"
+      ];
     };
   };
 
-  mkAdmin = name :
-  {hashedPassword, keys}: {
+  mkAdmin = name: {
+    hashedPassword,
+    keys,
+  }: {
     "${name}" = {
       isNormalUser = true;
       createHome = true;
-      extraGroups = [ "wheel" ];
+      extraGroups = ["wheel"];
       group = "users";
       home = "/home/${name}";
-      openssh.authorizedKeys = { inherit keys; };
+      openssh.authorizedKeys = {inherit keys;};
       inherit hashedPassword;
     };
   };
-
 in {
   users.users = mkMerge (mapAttrsToList mkAdmin admins);
 }
diff --git a/nixos/roles/default.nix b/nixos/roles/default.nix
index d92b970..60284a7 100644
--- a/nixos/roles/default.nix
+++ b/nixos/roles/default.nix
@@ -1,62 +1,72 @@
-{pkgs, config, lib, modulesPath, ...} : {
-
-imports = [
-  ./admins.nix
-  ./nix_keys.nix
-  ./prometheusNodeExporter.nix
-  (modulesPath + "/virtualisation/xen-domU.nix")
-  ../modules/impermanence.nix
+{
+  pkgs,
+  lib,
+  modulesPath,
+  ...
+}: {
+  imports = [
+    ./admins.nix
+    ./nix_keys.nix
+    ./prometheusNodeExporter.nix
+    (modulesPath + "/virtualisation/xen-domU.nix")
+    ../modules/impermanence.nix
   ];
-nix = {
-  extraOptions = ''
-    experimental-features = nix-command flakes
-    builders-use-substitutes = true
-  '';
-};
-
-networking = {
-  firewall = { # these shoud be default, but better make sure!
-    enable = true;
-    allowPing = true;
-  };
-  nftables.enable = true;
-  useDHCP = false; # We don't speak DHCP and even if we would, we should enable it per interface
-  # hosts = # TODO write something to autogenerate ip adresses!
-};
-
-users = {
-  mutableUsers = false;
-  users.root.hashedPassword = "!";
-};
-
-impermanence.enable = true;
-
-sops.age.sshKeyPaths = [ "/etc/ssh/ssh_host_ed25519_key" ];
-
-environment = {
-  systemPackages = builtins.attrValues {
-    inherit (pkgs)
-      htop lsof tmux btop;
-  };
-};
-
-services = {
-  journald.extraConfig = "SystemMaxUse=5G";
-
-  nginx = {
-    recommendedOptimisation = true;
-    recommendedGzipSettings = true;
-    recommendedTlsSettings = true;
+  nix = {
+    extraOptions = ''
+      experimental-features = nix-command flakes
+      builders-use-substitutes = true
+    '';
   };
 
-  openssh = {
-    enable = true;
-    settings = {
-      PermitRootLogin = "no";
-      PasswordAuthentication = false;
+  networking = {
+    firewall = {
+      # these shoud be default, but better make sure!
+      enable = true;
+      allowPing = true;
+    };
+    nftables.enable = true;
+    useDHCP = false; # We don't speak DHCP and even if we would, we should enable it per interface
+    # hosts = # TODO write something to autogenerate ip adresses!
+  };
+
+  users = {
+    mutableUsers = false;
+    users.root.hashedPassword = "!";
+  };
+
+  impermanence.enable = true;
+
+  sops.age.sshKeyPaths = ["/etc/ssh/ssh_host_ed25519_key"];
+
+  environment = {
+    systemPackages = builtins.attrValues {
+      inherit
+        (pkgs)
+        htop
+        lsof
+        tmux
+        btop
+        ;
     };
   };
-#Prevent clock drift due to interaction problem with xen hardware clock 
-  timesyncd.enable = lib.mkForce true;
-};
+
+  services = {
+    journald.extraConfig = "SystemMaxUse=5G";
+
+    nginx = {
+      recommendedOptimisation = true;
+      recommendedGzipSettings = true;
+      recommendedTlsSettings = true;
+    };
+
+    openssh = {
+      enable = true;
+      settings = {
+        PermitRootLogin = "no";
+        PasswordAuthentication = false;
+      };
+    };
+    #Prevent clock drift due to interaction problem with xen hardware clock
+    timesyncd.enable = lib.mkForce true;
+  };
 }
diff --git a/nixos/roles/nix_keys.nix b/nixos/roles/nix_keys.nix
index 14f0b56..97e5dc5 100644
--- a/nixos/roles/nix_keys.nix
+++ b/nixos/roles/nix_keys.nix
@@ -1,5 +1,5 @@
 {
-  imports = [ ];
+  imports = [];
   nix.settings.trusted-public-keys = [
     "nerflap2-1:pDZCg0oo9PxNQxwVSQSvycw7WXTl53PGvVeZWvxuqJc="
     "gonne.mathebau.de-1:FsXFyFiBFE/JxC9MCkt/WuiXjx5dkRI9RXj0FxOQrV0="
diff --git a/nixos/roles/prometheusNodeExporter.nix b/nixos/roles/prometheusNodeExporter.nix
index 9587b2f..37cdbc2 100644
--- a/nixos/roles/prometheusNodeExporter.nix
+++ b/nixos/roles/prometheusNodeExporter.nix
@@ -1,15 +1,14 @@
-{config, ...}:
-{
-  imports = [ ];
+{config, ...}: {
+  imports = [];
   services.prometheus.exporters.node = {
     enable = true;
     port = 9100;
-  # Aligned with https://git.rwth-aachen.de/fsdmath/server/prometheus/-/blob/main/node_exporter/etc/default/prometheus-node-exporter
-  # It was compiled along the following steps:
-  # 1. Does the current Debian release supports the collector?
-  # 2. Is the collector depracated in the latest release?
-  # 3. Could you probably use the collected metrics for monitoring or are they useless because they make no sense in our context
-  #    (e.g. power adapter inside a VM, use fibre port connection)?
+    # Aligned with https://git.rwth-aachen.de/fsdmath/server/prometheus/-/blob/main/node_exporter/etc/default/prometheus-node-exporter
+    # It was compiled along the following steps:
+    # 1. Does the current Debian release supports the collector?
+    # 2. Is the collector depracated in the latest release?
+    # 3. Could you probably use the collected metrics for monitoring or are they useless because they make no sense in our context
+    #    (e.g. power adapter inside a VM, use fibre port connection)?
     disabledCollectors = [
       "arp"
       "bcache"
@@ -35,6 +34,6 @@
       "processes"
     ];
   };
-  networking.firewall.allowedTCPPorts = [ 9100 ];
-  environment.persistence.${config.impermanence.name}.directories = [ "/var/lib/${config.services.prometheus.stateDir}" ];
+  networking.firewall.allowedTCPPorts = [9100];
+  environment.persistence.${config.impermanence.name}.directories = ["/var/lib/${config.services.prometheus.stateDir}"];
 }