nixos/jupyter: add package and command options

nixos/modules/services/development/jupyter/default.nix

@@ -6,10 +6,7 @@ let
 
   cfg = config.services.jupyter;
 
-  # NOTE: We don't use top-level jupyter because we don't
-  # want to pass in JUPYTER_PATH but use .environment instead,
-  # saving a rebuild.
-  package = pkgs.python3.pkgs.notebook;
+  package = cfg.package;
 
   kernels = (pkgs.jupyter-kernel.create  {
     definitions = if cfg.kernels != null
@@ -37,6 +34,27 @@ in {
       '';
     };
 
+    package = mkOption {
+      type = types.package;
+      # NOTE: We don't use top-level jupyter because we don't
+      # want to pass in JUPYTER_PATH but use .environment instead,
+      # saving a rebuild.
+      default = pkgs.python3.pkgs.notebook;
+      description = ''
+        Jupyter package to use.
+      '';
+    };
+
+    command = mkOption {
+      type = types.str;
+      default = "jupyter-notebook";
+      example = "jupyter-lab";
+      description = ''
+        Which command the service runs. Note that not all jupyter packages
+        have all commands, e.g. jupyter-lab isn't present in the default package.
+       '';
+    };
+
     port = mkOption {
       type = types.int;
       default = 8888;
@@ -157,7 +175,7 @@ in {
 
         serviceConfig = {
           Restart = "always";
-          ExecStart = ''${package}/bin/jupyter-notebook \
+          ExecStart = ''${package}/bin/${cfg.command} \
             --no-browser \
             --ip=${cfg.ip} \
             --port=${toString cfg.port} --port-retries 0 \