Nextcloud-snap: Unable to mount the snap

[tfgordon]

I am trying to install NextCloud on a hosted virtual machine running Ubuntu 16.04.2 LTS, but am getting a mounting error:

$ sudo snap install nextcloud
error: cannot perform the following tasks:

• Mount snap "core" (1337) ([start snap-core-1337.mount] failed with exit status 1: Job for snap-core-1337.mount failed. See "systemctl status snap-core-1337.mount" and "journalctl -xe" for details.
  )

$ sudo systemctl status snap-core-1337.mount
snap-core-1337.mount - Mount unit for core
Loaded: loaded (/etc/systemd/system/snap-core-1337.mount; enabled; vendor preset: enabled)
Active: failed (Result: exit-code) since Mi 2017-03-01 12:02:57 CET; 1min 0s ago
Where: /snap/core/1337
What: /var/lib/snapd/snaps/core_1337.snap
Process: 32662 ExecMount=/bin/mount /var/lib/snapd/snaps/core_1337.snap /snap/core/1337 -t squashfs (code=exited, status=32)

Any idea what the cause of the problem could be?

[kyrofa]

What does "a hosted virtual machine" mean? Hosted where? Are you sure this is official Ubuntu, kernel and everything? Because on first pass, it sounds like the kernel doesn't support squashfs.

Do you see relevant syslog entries when installing?

[tfgordon]

The file /var/log/syslog file doesn't provide any further informtion about the failure, other than "unknown error":

Mar 5 15:40:08 h2667230 /usr/lib/snapd/snapd[1892]: taskrunner.go:353: DEBUG: Running task 203 on Do: Mount snap "core" (1337)
Mar 5 15:40:09 h2667230 mount[5137]: mount: /snap/core/1337: mount failed: Unknown error -1
Mar 5 15:40:09 h2667230 /usr/lib/snapd/snapd[1892]: task.go:303: DEBUG: 2017-03-05T15:40:09+01:00 ERROR [start snap-core-1337.mount] failed with exit status 1: Job for snap-core-1337.mount failed. See "systemctl status snap-core-1337.mount" and "journalctl -xe" for details.

The hosted server claims to be running Ubuntu 16.04.2 LTS:

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 16.04.2 LTS
Release: 16.04
Codename: xenial

The kernel version is given as:

$ uname -a
Linux h2667230.stratoserver.net 4.4.0-042stab120.16 #1 SMP Tue Dec 13 20:58:28 MSK 2016 x86_64 x86_64 x86_64 GNU/Linux

Does "stratoserver" here suggest the kernal has been modified? (I will ask the ISP, strato.de, and let you know if I am able to find out.)

[tfgordon]

The ISP sent me an email telling me that snaps can be installed, but may not modify the Linux kernel. However, not only can I not install the Nextcloud snap, not even the demo hello-world snap can be installed. I get the same mounting error. So this does not seem to be a problem specific to the Nextcloud snap. I will contact the ISP again and ask for further help and get back to you.

[kyrofa]

The ISP sent me an email telling me that snaps can be installed, but may not modify the Linux kernel.

That's not quite what I meant-- I'm suggesting that the kernel they're using is not an official Ubuntu kernel: specifically, I'm suggesting that it doesn't include support for squashfs. To prove this, try the following:

$ sudo apt install squashfs-tools
$ cd /tmp
$ mkdir foo
$ mkdir baz
$ touch foo/bar
$ mksquashfs foo foo.squash
$ sudo mount foo.squash baz
$ ls baz/

Do you get any errors there?

[tfgordon]

Yes, I understand that you want to know whether the kernel has been modified. I have asked my ISP again. I tried your test to see if squashfs is supported. Everything worked except mounting:

$ sudo mount foo.squash baz
mount: baz: mount failed: Unknown error -1

I will also report this to the ISP.

[kyrofa]

Well at least you don't get "unknown filesystem type" or similar errors. So perhaps squashfs support is built in. But yeah, something else is missing there-- you need to be able to mount in order to install snaps.

[tfgordon]

I just spoke with the technical support at the ISP, strato.de, and was told that if something doesn't work as expected then this is due to a limitation of Virtuozzo, the virtualization software they use. I had previously been told that snaps were supported, so in my view these two pieces of advice are inconsistent. It was recommended that I upgrade to a dedicated server. But I decided instead to cancel my contract, within the 30 day grace period, to give me time to consider alternatives.

[kyrofa]

But I decided instead to cancel my contract, within the 30 day grace period, to give me time to consider alternatives.

Good call, and good investigation! I'm going to go ahead and close this, then.

[mayeaux]

@kyrofa I get a mount: unknown filesystem type 'squashfs' error, with OVH, am I screwed or what?

[kyrofa]

Yes, OVH does by default use a non-standard kernel. However, I've read a few articles that suggest it's possible to install the standard kernel on there. I suggest reaching out to OVH support to help.

[mayeaux]

Thanks, I've reached out to them so I'll bring that up when they get back. I'm not a Linux wizard, why won't squashfs work on non-standard kernels? Thanks again

[kyrofa]

Because like any typical filesystem, it requires kernel support, and it seems their kernel was built without support (whereas the standard ones have it). You can also suggest they enable support for it, but snaps also require other kernel features that may be disabled or missing features, such as apparmor.

[kyrofa]

If I may be so bold, by claiming they're offering Ubuntu but not actually giving you Ubuntu, they are at best offering you (and us, who try to support Ubuntu) a disservice, and at worst commiting a trademark violation. I suggest you tell them this and leave them for a more honest vendor.

[mayeaux]

Yeah, there's nothing mentioned in their advertising whatsoever that it's a nonstandard kernel and that that may have implications for trying to run basic software, unfortunately I've got quite a bit of infra set up on their systems already but we'll see what happens when I chat with their support, I definitely agree it should be mentioned clearly in their advertising (or at least while provisioning the OS)