cilium-cli: enable shell completion

pkgs/applications/networking/cluster/cilium/default.nix

@@ -1,4 +1,4 @@
-{ lib, buildGoModule, fetchFromGitHub }:
+{ lib, buildGoModule, fetchFromGitHub, installShellFiles }:
 
 buildGoModule rec {
   pname = "cilium-cli";
@@ -20,7 +20,6 @@ buildGoModule rec {
     "-X github.com/cilium/cilium-cli/internal/cli/cmd.Version=${version}"
   ];
 
-
   # Required to workaround install check error:
   # 2022/06/25 10:36:22 Unable to start gops: mkdir /homeless-shelter: permission denied
   HOME = "$TMPDIR";
@@ -30,6 +29,14 @@ buildGoModule rec {
     $out/bin/cilium version | grep ${version} > /dev/null
   '';
 
+  nativeBuildInputs = [ installShellFiles ];
+  postInstall = ''
+    installShellCompletion --cmd cilium \
+      --bash <($out/bin/cilium completion bash) \
+      --fish <($out/bin/cilium completion fish) \
+      --zsh <($out/bin/cilium completion zsh)
+  '';
+
   meta = with lib; {
     description = "CLI to install, manage & troubleshoot Kubernetes clusters running Cilium";
     license = licenses.asl20;