I spent two hours today trying to figure out why Nextcloud couldn’t read my data directory. Docker wasn’t mounting my data directory. Moved everything into my data directory. Docker couldn’t even see the configuration file.
Turns out the Docker Snap package only has access to files under the /home directory.
Moral of the story: never trust a Snap package.
But this is by design, snap containers aren’t allowed to read data outside of their confinements. Same goes for flatpak and OCI-containers.
I don’t use snap myself, but it does have its uses. Bashing it just because it’s popular to hate on snap won’t yield a healthy discussion on how it could be improved.
Ok then don’t publish an application that clearly needs access to files outside of the /home directory. Or at least be upfront about how limited it is when run as a snap.
Does it clearly need access to files outside the /home directory though?
You said your volume mount failed. How about mounting something inside your home folder into the docker container?
I have a 20TB RAID array that I use for a number of services mounted at /. I would like Nextcloud to have access to more than the 128GB available to /home. I’m not willing to move my data mount into /home and reconfigure the ~5 other services that use it just to work around some stupid Snap limitation. Who knows whether Snap even can access data across filesystems if they’re mounted in home. I wouldn’t put it past the Snap devs to fall down on that point either.
Yes, Docker clearly needs access to all files. It is meant for running server software, and server software is supposed to be flexible in its setup. To me, this limitation makes it completely unusable. Nextcloud is only the first service that needed access to that directory. I’ll also be running MinIO there for blob storage for a Mastodon server. I’ll probably move Jellyfin into a Docker container, and it’ll need access too.
The fact that this giant issue with Snap is not made clear is my biggest problem with it. I had to figure it out myself over the course of two hours when there are zero warnings or error messages explaining it. What an absolutely unnecessary waste of time, when it could have warned me at install that if I wanted a completely functional version of Docker, I should use the apt package.
I will never use any Snap package again. This was such a bad experience that I probably won’t even be using Ubuntu Server going forward. I already use Fedora for desktop. And the fact that a few people here are basically saying it’s my fault for not already knowing the limitations imposed on Snap packages is just making it more obvious that Ubuntu has become a toxic distro. It’s sad, because Ubuntu got me into Linux back with Hardy Heron 8.04. I’ve been running Ubuntu servers since 9.10. I used to be excited every six months for the new Ubuntu release. It’s sad to see something you loved become awful.
The issue here is that Canonical pushed the snap install without warning about its reduced functionality. I don’t think highlighting a wildly different experience between a snap install and the Docker experience people are used to from the standard package install is “bashing it just because it’s popular to hate on snap.” For example, if you take a fresh Ubuntu server 22 install and use the snap package, not realizing that snaps have serious limitations which are not explicitly called out when the snap is offered in the installation process, you’re going to be confused unless you already have that knowledge. It also very helpfully masks everything so debugging is incredibly difficult if you are not already aware of the snap limitations.
Friends don’t let friends use Snap.
Proprietary when flatpak exists, and it doesn’t properly address how apps should dynamically request access to things they need. Every time I’ve used either solution I’ve run into some permissions problem.
For desktop apps maybe. How do you run a flatpak from the cli? “flatpak run org.something.Command”. Awesome.
Both suffer from not making it obvious what directories your application can access and not providing a clear message when you try to access files it can’t. The user experience sucks.
“PSA: Snap sucks”
FTFY
Yah, it’s been trash from the start. I tried it 2 years ago and the unpredictable weird shit it did was useless to try to troubleshoot. It was worse than trying to run Docker on Windows, if that can be believed.
Debian with the Docker convenience script is the way to run Docker.
Docker has an apt repo. You can add it to your Debian/Ubuntu and install and update packages normally. No need to use a script install.
