I'd like to mention one exception, because it took me ages to properly debug.

If your endpoint is serving mirrors for APT, don't redirect to HTTPS.

APT packages are signed and validated, so there is no need to use TLS. Lot of docker images (such as Kali) do not have root certificates by default, so they can't use the TLS, because cert validation fails. You also can't install the certificates, because they install through APT. If your local mirror redirects to https by default, it will break it for people who choose the mirror, which IIRC happens automatically based on what's closest to you. I think this issue is still there for Czech Kali package mirror, and it took me so long to figure out (because it's also not an issue for most of the users, since they have different mirrors), so I like mentioning this when talking http/s. It's an edge case, but one that I find interresting - mostly because it would never occur to me that this can be an issue, when setting up a mirror.

But that was more than a year ago, it may be better now.