Added Nix flake with developer dependencies (#60)

Author: daniel-chambers

.envrc

@@ -0,0 +1,10 @@
+# Install nix-direnv which provides significantly faster Nix integration
+if ! has nix_direnv_version || ! nix_direnv_version 3.1.0; then
+  source_url "https://raw.githubusercontent.com/nix-community/nix-direnv/3.1.0/direnvrc" "sha256-yMJ2OVMzrFaDPn7q8nCBZFRYpL/f0RcHzhmw/i6btJM="
+fi
+
+# Apply the devShell configured in flake.nix
+use flake
+
+# this line sources your `.envrc.local` file
+source_env_if_exists .envrc.local

.gitignore

@@ -1,2 +1,3 @@
 node_modules
 dist
+.direnv/

flake.lock

@@ -0,0 +1,50 @@
+{
+  description = "ndc-nodejs-lambda development dependencies";
+
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixpkgs-unstable";
+    systems.url = "github:nix-systems/default";
+  };
+
+  outputs =
+    {
+      self,
+      nixpkgs,
+      systems,
+    }:
+    let
+      # Our default package set is configured to build for the same platform the flake is evaluated
+      # on. So we leave `crossSystem` set to the default, which is `crossSystem = localSystem`. With
+      # this package set if we're building on Linux we get Linux binaries, if we're building on Mac
+      # we get Mac binaries, etc.
+      mkPkgs =
+        localSystem:
+        import nixpkgs {
+          system = localSystem;
+        };
+
+      # Helper to define system-specific flake outputs.
+      perSystem =
+        callback:
+        nixpkgs.lib.genAttrs (import systems) (
+          system:
+          callback {
+            inherit system;
+            pkgs = mkPkgs system;
+          }
+        );
+    in
+    {
+      devShells = perSystem (
+        { pkgs, system }:
+        {
+          default = pkgs.mkShell {
+            packages = [
+              pkgs.nixfmt
+              pkgs.nodejs_20
+            ];
+          };
+        }
+      );
+    };
+}