This webapp acts as a redirect for user lookup requests. The idea is to make user lookups for @username@mastodon.senpai.moe redirect to the real instance that hosts the username, for some specific usernames only.
This allows the user to give out the @accountname@mastodon.senpai.moe username, and it will allow others to search that username within any Mastodon instance and get the redirected address.
The webapp also performs HTTP 301 profile redirects, from mastodon.senpai.moe/@username to the profile on the original server.
Custom domain redirects aren't explicitly supported by Mastodon, so this is only an experiment.
Users currently redirected by this subdomain:
https://mastodon.social/@nosgoroth
Please refer to this post by Maarten Balliauw for the original idea.
This webapp intercepts requests to https://mastodon.senpai.moe/.well-known/webfinger?resource=acct:username@mastodon.senpai.moe (via Apache mod_rewrite) and spits out the json that the original instance would spit for https://my.mastodon.instance/.well-known/webfinger?resource=acct:username@my.mastodon.instance.
Add users by editing _config.php. There are also additional options.