build: nix flakes

shell.nix

@@ -1,5 +1,22 @@
-{ pkgs ? import <nixpkgs> {} }:
+{ pkgs ? (
+    let
+      inherit (builtins) fetchTree fromJSON readFile;
+      inherit ((fromJSON (readFile ./flake.lock)).nodes) nixpkgs gomod2nix;
+    in
+    import (fetchTree nixpkgs.locked) {
+      overlays = [
+        (import "${fetchTree gomod2nix.locked}/overlay.nix")
+      ];
+    }
+  )
+}:
 
-with pkgs; mkShell {
-  packages = [ go gcc qemu podman ];
+let
+  goEnv = pkgs.mkGoEnv { pwd = ./.; };
+in
+pkgs.mkShell {
+  packages = [
+    goEnv
+    pkgs.gomod2nix
+  ];
 }