Disallow search engines from indexing my code

I don't really want my code to be discoverable, I only want people looking at it
if I have explicitly told them about it.

I tested it like so:

    ϟ curl -v https://simatime.com/git/ 2>&1 | rg x-robots
    < x-robots-tag: noindex, follow

1 files changed, 15 insertions, 0 deletions

diff --git a/Biz/Cloud/Cgit.nix b/Biz/Cloud/Cgit.nix
index 78eda7b..0b3a71b 100644
--- a/Biz/Cloud/Cgit.nix
+++ b/Biz/Cloud/Cgit.nix
@@ -36,6 +36,14 @@ in
               Location to serve cgit on.
             '';
           };
+
+          allowCrawlers = mkOption {
+            default = true;
+            type = types.bool;
+            description = ''
+              Allow search engines to crawl and index this site.
+            '';
+          };
         };
 
         # Remove the global options for serialization into cgitrc
@@ -108,6 +116,13 @@ in
                   fastcgi_split_path_info  ^(${location}/)(/?.+)$;
                   fastcgi_param  PATH_INFO  $fastcgi_path_info;
                 ''
+            ) + (
+              if !cfg.allowCrawlers
+              then
+                ''
+                  add_header X-Robots-Tag "noindex, follow" always;
+                ''
+              else ""
             );
           };
         };