Hi Buttshill,
interesting question, as web apps complicate things significantly: Here's a bit of a TLDR, skip to bottom for answer:
I messed around with the 'packaged' version of some web apps, and got caught out, luckily not badly, but enough to learn about them and how to get around it.
I got caught with joomla (a web site CMS), just a local one for my small business for my staff, it was all ok, then I updated from one version of Mageia to the newer, and it broke my joomla site, IIRC it went from version 1.5XXX to 2.0XXX, and of course my data wouldn't work with the new joomla version: That's not 100% mageia's fault, I doubt I read the release notes, and I didn't have a manual back up.
Now that's another point: Web app back ups!!!!! There's usually 3 (yes three) directories/data sets you need to back up, and usually NONE ARE PART OF /HOME. These are:
1: The web app itself eg /var/www/html/webapp
2: The directory the web app uses for data storage eg /usr/share/www/webapp
3: The database info, that has to be 'dumped' into a file using the correct command, google is your friend here, I use mariadb (mysqld equivilent) and theres a billion tutorials about how to perform the dump
And there may also be some configs to copy also, these can be a nightmare to rebuild, so back them up:
In my case there is /etc/webapp and /etc/www/config , or it's something like that, I'm not in front of my server now.
So, what I should have done is backed all that up, then performed the update, if it failed, i could have then messed around trying to sort it out..... But given the data wasn't really important I just moved on.
Then I found myself in an owncloud position like yourself. This was on my raspberry pi (no mageia image at the time) so I used Fedora (nice, but no Mandrake successor). And owncloud was their package at the time (like version 8 or something). Incidentally this is a good read
https://www.happyassassin.net/2015/08/2 ... -packages/, basically web apps suck for packaging....
So I can't remember what happened, but I think one of my other systems had the owncloud/nextcloud client updated, and then it wouldn't talk to the 'old' owncloud server.... blast... I talked on IRC to the fedora boys a bit, but basically they didn't know when the update was coming... What to do, what to do...
So I dug deep and wasted hours upon hours of my life.... What I did was I did that whole back up thing. I then 'exempted' owncloud packages from being updated via the DNF config file. I then went on a deep dive learning how to 'update' owncloud manually: ie: shutdown apache, move the old web app to a backup directory, download and extract the new version of owncloud, move into place, perform the 'occ update' commands, restart apache. It was a bit more messy than that as I had to link in the existing config.php etc, but I managed to update it through several versions without it breaking... Was so proud of myself.
Then the whole open source/financer issue blew up: The devs left owncloud and started nextcloud... so I migrated over.. And that worked. I did several manual updates also over time. Somewhere through that I had about 4 SD cards die in my pi, so I ended up with a nice clean install of fedora with no dodgy DNF exemptions being worked around.
Then somewhere along the line, the nextcloud devs stepped up to a whole new level and introduced the 'web based' updater. What a revolution. Log in as maintainer/root/authority, go to settings, click web based updater and it's done!! Not quite, but after all the CLI rot I was used to, it works perfectly (most of the time, the early ones were a bit iffy, but now it hasn't failed on me in a long time).
-----Answer below------
From my experience, I sincerely DO NOT recommend using packaged web apps. Not magiea's fault, not the web apps fault, it is just a complex task.
So here's what I recommend: In MY order of recommendation:
1: Learn (really just follow a tutorial, or post here/irc and you'll get the help you need, but it may take some time) how to install the web app manually ie: Download the web app from it's website/github. Extract and install it, install it's dependencies via the package manager though ie. use urpmi/dnf to install apache, php etc etc, but the actual app, download that manually. Then learn how to update it manually. Most apps are pretty straight forward to update now, one of mine I have to download the update, drop it in a directory, then go to the web apps page as admin and it will find it and apply it. Nextcloud can do it from the web page, or cli if you just want to do it that way.
2: You could probably do what I did initially with my owncloud install. Use urpmi to install the server, then exempt it from updates, then manually manage it yourself. While that makes it easy to install all the dependencies, learning where the links are for the config.php etc can be a bloody pain, and I remember with fedora that took a few hours of messing around to learn where their packagers think stuff should be put eg config.php is put in /etc/owncloud/config.php, while where config.php normally is has a link over to the actual file.
3: Use a specific VM for that task. I haven't used it, but there are projects like
https://ownyourbits.com/nextcloudpi/ that build a great eco system around the app, and that's all it does.
So if I understand correctly, you currently have version 15 installed from the repos via urpmi? Then NO, DO NOT use the update function in nextcloud, that will cause merry hell when the package maintainer pushes the updated version (although, I just had a thought, there may be an updated version in backports?? Have you checked??? But I would advise against that for reasons above). If this is the case I would exempt nextcloud from urmpi updates, THEN you can use the update function in nextcloud.
But back up, backup, back up.