Use flake

.envrc

@@ -1 +1 @@
-use nix
+use flake

flake.nix

@@ -0,0 +1,62 @@
+{
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    flake-parts = {
+      url = "github:hercules-ci/flake-parts";
+      inputs.nixpkgs-lib.follows = "nixpkgs";
+    };
+    rust-overlay.url = "github:oxalica/rust-overlay";
+  };
+
+  outputs =
+    inputs@{ self, flake-parts, ... }:
+    flake-parts.lib.mkFlake { inherit inputs; } {
+      systems = [
+        "x86_64-linux"
+        "aarch64-linux"
+      ];
+
+      perSystem =
+        {
+          config,
+          self',
+          inputs',
+          pkgs,
+          system,
+          ...
+        }:
+        {
+          _module.args.pkgs = import self.inputs.nixpkgs {
+            inherit system;
+            overlays = [
+              (import inputs.rust-overlay)
+            ];
+          };
+          devShells.default =
+            let
+              libPath =
+                with pkgs;
+                lib.makeLibraryPath [
+                  pkg-config
+                  openssl
+                ];
+            in
+            pkgs.mkShell {
+              inputsFrom = builtins.attrValues self'.packages;
+              packages = with pkgs; [
+                # (rust-bin.selectLatestNightlyWith (toolchain: toolchain.default))
+                pkg-config
+                openssl
+                cargo
+                cargo-watch
+                rustc
+                rust-analyzer
+                clippy
+              ];
+              LD_LIBRARY_PATH = libPath;
+              RUST_BACKTRACE = 1;
+              LIBCLANG_PATH = "${pkgs.libclang.lib}/lib";
+            };
+        };
+      };
+}