Just set up nginx caching and wondering whether it’s working properly? You can check it pretty easily: curl -I URL.goes.here That should return a bunch of information, but the important bit is: X-Proxy-Cache: MISS Well, in this case it’s not working. If it’s working you’ll see a HIT there.
If you have a lot of virtual (or real) machines running Debian or Ubuntu and a limited internet connection, it can make a lot of sense to use apt-cacher-ng to create a local cache of the packages you use so that they are only downloaded once. The current version of apt-cacher-ng can also help…