feat(k3s): add enable option

modules/k3s/default.nix

@@ -1,27 +1,26 @@
-{ pkgs, ... }:
-
 {
-  # TODO: see if this works with podman
+  lib,
-  # TODO: check if docker/podman is enabled
+  config,
+  pkgs,
+  ...
+}:
 
-  # Rootless K3S
+let
+  cfg = config.k3s;
+in
+{
+  options.k3s.enable = lib.mkEnableOption "k3s rootless";
 
-  # FIXME
+  config = lib.mkIf cfg.enable {
     environment.systemPackages = with pkgs; [
       k3s
       rootlesskit
       slirp4netns
     ];
 
-  # running K3S on rootless docker was causing the following error: "failed to find cpuset cgroup (v2)" (in `docker logs k3d-lab-server-0` output)
-  #
-  # see <https://docs.k3s.io/advanced#known-issues-with-rootless-mode>
-  # see <https://rootlesscontaine.rs/getting-started/common/cgroup2/>
-  # see <https://discourse.nixos.org/t/declarative-rootless-k3s/49839>
     systemd.services."user@".serviceConfig.Delegate = "cpu cpuset io memory pids";
 
-  # taken from <https://github.com/k3s-io/k3s/blob/main/k3s-rootless.service> as described in <https://docs.k3s.io/advanced#known-issues-with-rootless-mode#Rootless>
+    systemd.user.services."k3s-rootless" = {
-  systemd.user.services."k3s-rootless" = with pkgs; {
       path = with pkgs; [
         "${rootlesskit}"
         "${slirp4netns}"
@@ -29,32 +28,10 @@
         "${fuse3}"
         "/run/wrappers"
       ];
-    # systemd unit file for k3s (rootless)
-    #
-    # Usage:
-    # - [Optional] Enable cgroup v2 delegation, see https://rootlesscontaine.rs/getting-started/common/cgroup2/ .
-    #   This step is optional, but highly recommended for enabling CPU and memory resource limtitation.
-    #
-    # - Copy this file as `~/.config/systemd/user/k3s-rootless.service`.
-    #   Installing this file as a system-wide service (`/etc/systemd/...`) is not supported.
-    #   Depending on the path of `k3s` binary, you might need to modify the `ExecStart=/usr/local/bin/k3s ...` line of this file.
-    #
-    # - Run `systemctl --user daemon-reload`
-    #
-    # - Run `systemctl --user enable --now k3s-rootless`
-    #
-    # - Run `KUBECONFIG=~/.kube/k3s.yaml kubectl get pods -A`, and make sure the pods are running.
-    #
-    # Troubleshooting:
-    # - See `systemctl --user status k3s-rootless` to check the daemon status
-    # - See `journalctl --user -f -u k3s-rootless` to see the daemon log
-    # - See also https://rootlesscontaine.rs/
       enable = true;
       description = "k3s (Rootless)";
       serviceConfig = {
-      # NOTE: Don't try to run `k3s server --rootless` on a terminal, as it doesn't enable cgroup v2 delegation.
+        ExecStart = "${pkgs.k3s}/bin/k3s server --rootless --snapshotter=fuse-overlayfs";
-      # If you really need to try it on a terminal, prepend `systemd-run --user -p Delegate=yes --tty` to create a systemd scope.
-      ExecStart = "${k3s}/bin/k3s server --rootless --snapshotter=fuse-overlayfs";
         ExecReload = "/run/current-system/sw/bin/kill -s HUP $MAINPID";
         TimeoutSec = 0;
         RestartSec = 2;
@@ -69,11 +46,11 @@
         Type = "simple";
         KillMode = "mixed";
       };
-
       wantedBy = [ "default.target" ];
     };
 
     boot.kernel.sysctl = {
       "net.ipv4.ip_forward" = 1;
     };
+  };
 }