Federation: how does it work?


I am wondering whether to set up federation with another Nextcloud that is run by someone else. What I can’t seem to find information on is what would then happen in terms of data transfers between the two instances. So this is both about possible storage issues and privacy.

I have seen that an increasing number of features/apps support federation, so I would also wonder if any answer given now might change.

But mainly, I would like to know about federated file shares: are files mirrored/replicated/cached between the two instances? Are user lists shared?

Thanks for any replies.

Which specifically? Very limited support for federation outside of files.

You wrote about this yourself but if that is not the case, let’s not get distracted by that … I’d be happy for answers just about file sharing.

Well, looks like what I wrote is basically same today as it was in 2022. Let me know if any questions on that.

Sure thing. Documentation for exactly how this works is available at Configuring Federation Sharing — Nextcloud latest Administration Manual latest documentation

I think also interesting is a documention of the server-server-communication at federation. Is it “normal” WebDAV? What about authentication and autorization? Is there also a documentation or can someone explain it.

I think you can use every public downloadable link for federation. Use the download option “Add to my Nextcloud”. Maybe federation must be allowed.

I found that documentation and read it before I wrote. This is exactly why I opened this thread – this does not answer my questions. It is very much an admin user guide as it tells an admin what to do to set up federation. It does not explain what will happen. It does talk about setting up a trust relationship for auto-filling user names, which led me to include transmitting user names in my question.

What is missing and quite necessary (in my opinion and unless I overlooked something) is a concentrated and comprehensive explanation of what will happen between the two servers if federation is set up in this way. My questions at the top of this thread may not be all. Admins (or maybe managers) need to know this if they want to decide on whether to use federation.

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