start set up for multi-location nixos flake

nixos/hosts/olympus/k3s/configuration.nix

@@ -0,0 +1,52 @@
+{ config, pkgs, lib, ... }: {
+  imports = [
+    # Include the results of the hardware scan.
+    ./hardware-configuration.nix
+  ];
+
+  # Use the GRUB 2 boot loader.
+  boot.loader.grub = {
+    enable = true;
+    version = 2;
+    device = "/dev/sda";
+  };
+
+  boot.kernel.sysctl."fs.inotify.max_user_instances" = 2147483647; # INT_MAX, dynamically limited based on available memory
+  boot.kernel.sysctl."fs.inotify.max_user_watches" = 1048576;
+
+  networking.hostName = "k3s-node1";
+
+  # This value determines the NixOS release from which the default
+  # settings for stateful data, like file locations and database versions
+  # on your system were taken. It‘s perfectly fine and recommended to leave
+  # this value at the release version of the first install of this system.
+  # Before changing this value read the documentation for this option
+  # (e.g. man configuration.nix or on https://nixos.org/nixos/options.html).
+  system.stateVersion = "21.05"; # Did you read the comment?
+
+  # Additional packages
+  environment.systemPackages = with pkgs; [ iptables vim ];
+
+  # Disable the firewall as we need all the ports
+  networking.firewall.enable = false;
+
+  # Force-enable Cgroupv2
+  systemd.enableUnifiedCgroupHierarchy = lib.mkForce true;
+
+  # Ensure `mount` and `grep` are available 
+  systemd.services.k3s.path = [ pkgs.gnugrep pkgs.utillinux ];
+
+  # Enable k3s as a master node
+  services.k3s = {
+    enable = true;
+    role = "server";
+
+    extraFlags = builtins.toString [
+      "--data-dir=/var/lib/k3s" # Set data dir to var lib
+      "--cluster-init" # Enable embedded etcd
+      "--disable=servicelb" # disable servicelb
+      "--no-deploy=traefik" # we want to configure traefik ourselves (or use nginx instead)
+      "--cluster-cidr=10.69.0.0/16" # the default of 10.42.0.0/16 clashes with my own network
+    ];
+  };
+}