Added Nix development flake

flake.nix

@@ -0,0 +1,111 @@
+{
+  description = "Nix Development Flake for Game of Active Directory (GOAD)";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+  };
+
+  outputs = { self, nixpkgs, ... }:
+    let
+      system = "x86_64-linux";
+      pkgs = import nixpkgs {
+        inherit system;
+        config = { allowUnfree = true; };
+      };
+      libvirtShell = pkgs.mkShell {
+        buildInputs = with pkgs; [
+          vagrant
+          qemu_kvm 
+          libvirt
+          ebtables 
+          libguestfs
+          ruby
+          wget
+          unzip
+          python3
+        ];
+        shellHook = ''
+          # Vagrant plugins
+          if command -v vagrant >/dev/null 2>&1; then
+            for plugin in vagrant-reload winrm winrm-fs winrm-elevated; do
+                vagrant plugin install "$plugin" || true
+            done
+          fi
+          # Set provider to libvirt
+          if [ -z "$GOAD_SHELL_STARTED" ] && [ -x ./goad.sh ]; then
+            export GOAD_SHELL_STARTED=1
+            ./goad.sh --provider libvirt || true
+          fi
+        '';
+      };
+      vmwareShell = pkgs.mkShell {
+        buildInputs = with pkgs; [
+          vagrant
+          ruby
+          wget
+          unzip
+          python3
+        ];
+        shellHook = ''
+            # Vagrant plugins
+          if command -v vagrant >/dev/null 2>&1; then
+            for plugin in vagrant-reload vagrant-vmware-desktop winrm winrm-fs winrm-elevated; do
+                vagrant plugin install "$plugin" || true
+            done
+          fi
+          # Set provider to vmware
+          if [ -z "$GOAD_SHELL_STARTED" ] && [ -x ./goad.sh ]; then
+            export GOAD_SHELL_STARTED=1
+            ./goad.sh --provider vmware || true
+          fi
+        '';
+      };
+      virtualboxShell = pkgs.mkShell {
+        buildInputs = with pkgs; [
+          vagrant
+          virtualbox
+          ruby
+          wget
+          unzip
+          python3
+        ];
+        shellHook = ''
+          # Vagrant plugins
+          if command -v vagrant >/dev/null 2>&1; then
+            for plugin in vagrant-reload vagrant-vbguest winrm winrm-fs winrm-elevated; do
+                vagrant plugin install "$plugin" || true
+            done
+          fi
+          if [ -z "$GOAD_SHELL_STARTED" ] && [ -x ./goad.sh ]; then
+            export GOAD_SHELL_STARTED=1
+            ./goad.sh --provider virtualbox || true
+          fi
+        '';
+      };
+    in {
+      devShells.${system} = {
+        libvirt = libvirtShell;
+        vmware = vmwareShell;
+        virtualbox = virtualboxShell;
+        default = pkgs.mkShell {
+          name = "goad-devshell-usage";
+          shellHook = ''
+            cat <<'USAGE'
+
+            Choose a provider, for example:
+
+              nix develop .#libvirt
+              nix develop .#virtualbox
+              nix develop .#vmware
+
+            List available dev shells with:
+
+              nix flake show
+
+            USAGE
+            exit 1
+          '';
+        };
+      };
+    };
+}