kapp: install completion

pkgs/tools/networking/kapp/default.nix

@@ -1,4 +1,4 @@
-{ lib, buildGoModule, fetchFromGitHub }:
+{ lib, buildGoModule, fetchFromGitHub, installShellFiles }:
 buildGoModule rec {
   pname = "kapp";
   version = "0.36.0";
@@ -14,6 +14,15 @@ buildGoModule rec {
 
   subPackages = [ "cmd/kapp" ];
 
+  nativeBuildInputs = [ installShellFiles ];
+
+  postInstall = ''
+    for shell in bash fish zsh; do
+      $out/bin/kapp completion $shell > kapp.$shell
+      installShellCompletion kapp.$shell
+    done
+  '';
+
   meta = with lib; {
     description = "CLI tool that encourages Kubernetes users to manage bulk resources with an application abstraction for grouping";
     homepage = "https://get-kapp.io";