[Guide] Increase privacy by using nginx as a caching proxy in front of a map tile server

This is a guide I wrote for Immich's documentation. It features some Immich specific parts, but should be quite easy to adapt to other use cases.

It is also possible (and not technically hard) to self-host a protomaps release, but this would require 100GB+ of disk space (which I can't spare right now). The main advantages of this guide over hosting a full tile server are :

• it's a single nginx config file to deploy
• it saves you some storage space since you're only hosting tiles you've previously viewed. You can also tweak the maximum cache size to your needs
• it is easy to configure a trade-off between map freshness and privacy by tweaking the cache expiration delay

If you try to follow it, please send me some feedback on the content and the wording, so I can improve it