add copywrite to nix dev shell

flake.nix

@@ -6,19 +6,40 @@
     flake-utils.url = "github:numtide/flake-utils";
   };
 
-  outputs = { self, nixpkgs, flake-utils, ... }:
+  outputs =
+    {
+      self,
+      nixpkgs,
+      flake-utils,
+      ...
+    }:
     flake-utils.lib.eachDefaultSystem (
       system:
       let
-        pkgs = nixpkgs.legacyPackages.${system};
-        buildDeps = with pkgs; [ git go_1_21 gnumake ];
-        devDeps = with pkgs;
-          buildDeps ++ [
+        overlay = import ./nix/pkgs;
+
+        pkgs = import nixpkgs {
+          inherit system;
+          overlays = [ overlay ];
+        };
+
+        buildDeps = with pkgs; [
+          git
+          go_1_21
+          gnumake
+        ];
+
+        devDeps =
+          with pkgs;
+          buildDeps
+          ++ [
             easyjson
             goreleaser
+            copywrite
           ];
       in
-      { devShell = pkgs.mkShell { buildInputs = devDeps; }; }
+      {
+        devShell = pkgs.mkShell { buildInputs = devDeps; };
+      }
     );
-
 }

nix/pkgs/copywrite.nix

@@ -0,0 +1,56 @@
+{
+  lib,
+  buildGoModule,
+  fetchFromGitHub,
+  installShellFiles,
+  testers,
+  copywrite,
+}:
+
+buildGoModule rec {
+  pname = "copywrite";
+  version = "0.19.0";
+
+  src = fetchFromGitHub {
+    owner = "hashicorp";
+    repo = "copywrite";
+    rev = "6ed520a710166c6094098b786c63f212604654a4"; # matches tag release
+    hash = "sha256-DmlPioaw/wMk8GoBYNG24P4J1C6h0bjVjjOuMYW6Tgo=";
+  };
+
+  vendorHash = "sha256-ZIu0/fue3xi+YVE9GFsVjCNs8t3c3TWH8O0xUzJdim8=";
+
+  shortRev = builtins.substring 0 7 src.rev;
+
+  ldflags = [
+    "-s"
+    "-w"
+    "-X github.com/hashicorp/copywrite/cmd.version=${version}"
+    "-X github.com/hashicorp/copywrite/cmd.commit=${shortRev}"
+  ];
+
+  CGO_ENABLED = 0;
+
+  nativeBuildInputs = [ installShellFiles ];
+  postInstall = ''
+    $out/bin/copywrite completion bash > copywrite.bash
+    $out/bin/copywrite completion zsh > copywrite.zsh
+    $out/bin/copywrite completion fish > copywrite.fish
+    installShellCompletion copywrite.{bash,zsh,fish}
+  '';
+
+  passthru.tests.version = testers.testVersion {
+    package = copywrite;
+    command = "copywrite --version";
+    version = "${version}-${shortRev}";
+  };
+
+  meta = {
+    description = "Automate copyright headers and license files at scale";
+    mainProgram = "copywrite";
+    homepage = "https://github.com/hashicorp/copywrite";
+    changelog = "https://github.com/hashicorp/copywrite/releases/tag/v${version}";
+    license = lib.licenses.mpl20;
+    maintainers = with lib.maintainers; [ dvcorreia ];
+  };
+}

nix/pkgs/default.nix

@@ -0,0 +1,3 @@
+final: prev: {
+  copywrite = final.callPackage ./copywrite.nix { };
+}