From c5cc13fad8986021a24588ba9ad8b959e4223827 Mon Sep 17 00:00:00 2001
From: Rodrigo Arias Mallo <rodrigo.arias@bsc.es>
Date: Wed, 29 Oct 2025 12:21:18 +0100
Subject: [PATCH 1/2] Add nixgen package
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Reviewed-by: Aleix Boné <abonerib@bsc.es>
---
 overlay.nix             |  1 +
 pkgs/nixgen/default.nix | 22 ++++++++++
 pkgs/nixgen/nixgen      | 97 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 120 insertions(+)
 create mode 100644 pkgs/nixgen/default.nix
 create mode 100755 pkgs/nixgen/nixgen

diff --git a/overlay.nix b/overlay.nix
index 3b02ae30..b737daed 100644
--- a/overlay.nix
+++ b/overlay.nix
@@ -37,6 +37,7 @@ let
     nanos6 = callPackage ./pkgs/nanos6/default.nix { };
     nanos6Debug = final.nanos6.override { enableDebug = true; };
     nixtools = callPackage ./pkgs/nixtools/default.nix { };
+    nixgen = callPackage ./pkgs/nixgen/default.nix { };
     # Broken because of pkgsStatic.libcap
     # See: https://github.com/NixOS/nixpkgs/pull/268791
     #nix-wrap = callPackage ./pkgs/nix-wrap/default.nix { };
diff --git a/pkgs/nixgen/default.nix b/pkgs/nixgen/default.nix
new file mode 100644
index 00000000..455556b7
--- /dev/null
+++ b/pkgs/nixgen/default.nix
@@ -0,0 +1,22 @@
+{
+  stdenv
+, lib
+}:
+
+stdenv.mkDerivation {
+  pname = "nixgen";
+  version = "0.0.1";
+  src = ./nixgen;
+  dontUnpack = true;
+  phases = [ "installPhase" ];
+  installPhase = ''
+    mkdir -p $out/bin
+    cp -a $src $out/bin/nixgen
+  '';
+  meta = {
+    description = "Quickly generate flake.nix from command line";
+    maintainers = with lib.maintainers.bsc; [ rarias ];
+    platforms = lib.platforms.linux;
+    license = lib.licenses.gpl3Plus;
+  };
+}
diff --git a/pkgs/nixgen/nixgen b/pkgs/nixgen/nixgen
new file mode 100755
index 00000000..557e0fed
--- /dev/null
+++ b/pkgs/nixgen/nixgen
@@ -0,0 +1,97 @@
+#!/bin/sh
+#
+# Copyright (c) 2025, Barcelona Supercomputing Center (BSC)
+# SPDX-License-Identifier: GPL-3.0+
+# Author: Rodrigo Arias Mallo <rodrigo.arias@bsc.es>
+
+function usage() {
+  echo "USAGE: nixgen [-f] [package [...]] [-b package [...]]" >&2
+  echo "  Generates a flake.nix file with the given packages." >&2
+  echo "  After flake.nix is created, use 'nix develop' to enter the shell." >&2
+  echo "OPTIONS" >&2
+  echo "  -f               Overwrite existing flake.nix (default: no)." >&2
+  echo "  packages...      Add these packages to the shell." >&2
+  echo "  -b packages...   Add the dependencies needed to build these packages." >&2
+  echo "EXAMPLE" >&2
+  echo "  $ nixgen ovni bigotes -b nosv tampi" >&2
+  echo "  Adds the packages ovni and bigotes as well as all required dependencies" >&2
+  echo "  to build nosv and tampi." >&2
+  echo "AUTHOR" >&2
+  echo "  Rodrigo Arias Mallo <rodrigo.arias@bsc.es>" >&2
+  exit 1
+}
+
+mode=package
+packages=
+inputsFrom=
+force=
+
+if [[ $# -eq 0 ]]; then
+  usage
+fi
+
+while [[ $# -gt 0 ]]; do
+    case $1 in -b)
+      mode=build
+      shift
+      ;;
+    -f)
+      force=1
+      shift
+      ;;
+    -h)
+      usage
+      ;;
+    -*|--*)
+      echo "error: unknown option $1" >&2
+      exit 1
+      ;;
+    *)
+      if [ "$mode" == "package" ]; then
+        packages+="${packages:+ }$1"
+      else
+        inputsFrom+="${inputsFrom:+ }$1"
+      fi
+      shift
+      ;;
+  esac
+done
+
+if [ ! "$force" -a -e flake.nix ]; then
+  echo "error: flake.nix exists, force overwrite with -f" >&2
+  exit 1
+fi
+
+cat > flake.nix <<EOF
+{
+  inputs.jungle.url = "git+https://jungle.bsc.es/git/rarias/jungle";
+  outputs = { self, jungle }:
+  let
+    nixpkgs = jungle.inputs.nixpkgs;
+    customOverlay = (final: prev: {
+      # Example overlay, for now empty
+    });
+    pkgs = import nixpkgs {
+      system = "x86_64-linux";
+      overlays = [
+        # Apply jungle overlay to get our BSC custom packages
+        jungle.outputs.bscOverlay
+        # And on top apply our local changes to customize for cluster
+        customOverlay
+      ];
+    };
+  in {
+    devShells.x86_64-linux.default = pkgs.mkShell {
+      pname = "devshell";
+      # Include these packages in the shell
+      packages = with pkgs; [
+        $packages
+      ];
+      # The dependencies needed to build these packages will be also included
+      inputsFrom = with pkgs; [
+        $inputsFrom
+      ];
+    };
+  };
+}
+EOF
-- 
2.49.0


From 5ff1b1343b734a4aab5fea91823ebd78043e3897 Mon Sep 17 00:00:00 2001
From: Rodrigo Arias Mallo <rodrigo.arias@bsc.es>
Date: Wed, 29 Oct 2025 12:39:05 +0100
Subject: [PATCH 2/2] Add nixgen to all machines
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Reviewed-by: Aleix Boné <abonerib@bsc.es>
---
 m/common/base/env.nix | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/m/common/base/env.nix b/m/common/base/env.nix
index e5530501..d23dc73c 100644
--- a/m/common/base/env.nix
+++ b/m/common/base/env.nix
@@ -5,8 +5,8 @@
     vim wget git htop tmux pciutils tcpdump ripgrep nix-index nixos-option
     nix-diff ipmitool freeipmi ethtool lm_sensors cmake gnumake file tree
     ncdu config.boot.kernelPackages.perf ldns pv
-    # From bsckgs overlay
-    osumb
+    # From jungle overlay
+    osumb nixgen
   ];
 
   programs.direnv.enable = true;
-- 
2.49.0