add flake.lock devShell

flake.lock

@@ -0,0 +1,27 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1697723726,
+        "narHash": "sha256-SaTWPkI8a5xSHX/rrKzUe+/uVNy6zCGMXgoeMb7T9rg=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "7c9cc5a6e5d38010801741ac830a3f8fd667a7a0",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,34 @@
+{
+  description = "stadtratmonitor-rs devShell";
+
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = {
+    self,
+    nixpkgs,
+    flake-utils,
+    ...
+  }:
+    flake-utils.lib.eachDefaultSystem (
+      system: let
+        pkgs = nixpkgs.legacyPackages.${system};
+      in {
+        devShells.default = pkgs.mkShell {
+          packages = builtins.attrValues {
+            inherit
+              (pkgs.buildPackages)
+              cargo
+              cargo-watch
+              openssl
+              pkg-config
+              rustc
+              rustfmt
+              ;
+          };
+        };
+      }
+    );
+}