nbd-client fails to connect Error: Socket failed: Connection refused

[Thiago Martins]

[ Impact ]

nbdtab uses a port of 0 by default which is not sensible. This means that if you do not set a default port in nbdtab, it will fail.

You will see an error such as: Error: Socket failed: Connection refused

[ Test Plan ]

$ lxc launch ubuntu:noble n-vm --vm
$ lxc shell n-vm
# apt update -y && apt install -y nbd-client nbd-server
# dpkg -s nbd-client | grep Version:
Version: 1:3.26.1-1build1
# modprobe nbd
# truncate -s 1T /vol-0.img
# cat > /etc/nbd-server/conf.d/exports.conf << _EOF_
[vol0]
exportname = /vol-0.img
_EOF_
# systemctl restart nbd-server.service

Verify that NBD is working properly:

# nbd-client localhost /dev/nbd0 -name vol0

It should work.

To clean it up:

# nbd-client -d /dev/nbd0

Now, trigger the problem:

# cat >> /etc/nbdtab << _EOF_
nbd0 localhost vol0
_EOF_
# nbd-client nbd0

You should see the error:

# nbd-client nbd0
Error: Socket failed: Connection refused

Test the fix:
# add-apt-repository -y ppa:mitchdz/lp2060745-nbd-port-fix
# apt update -y && apt upgrade -y
# dpkg -s nbd-client | grep Version:
Version: 1:3.26.1-1ubuntu0.1~noble1
# nbd-client -d /dev/nbd0
< no errors here>

[ Where problems could occur ]
* This changes the default port, so issues using custom ports could arise. This seems unlikely since it is a one line change that should get overridden.

[Thiago Martins (martinx)]

It seems to be an upstream issue: https://github.com/NetworkBlockDevice/nbd/issues/156

[Athos Ribeiro (athos-ribeiro)]

It seems that this has been fixed upstream in https://github.com/NetworkBlockDevice/nbd/commit/256f95a529f3d7128afbb890c11c2ebf4750d16f.

[Andreas Hasenack (ahasenack)]

a) Please upload this fix to Oracular as well.

b) Interesting, this was failing in noble already before the release, i.e., the existing DEP8 test covered this scenario already: https://autopkgtest.ubuntu.com/packages/nbd/noble/amd64

[Andreas Hasenack (ahasenack)]

Hello Thiago, or anyone else affected,

Accepted nbd into noble-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/nbd/1:3.26.1-1ubuntu0.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, what testing has been performed on the package and change the tag from verification-needed-noble to verification-done-noble. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-noble. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

[Mitchell Dzurick (mitchdz)]

Thanks Andreas!

Regarding comment #3

a) debian version has this fix, and quite a few updates to the debian/* directory, so I think we might as well do an early oracular merge to get that fix in.

B) I'm curious why the excuses page didn't pick up those autopkgtests during the sync?

[Mitchell Dzurick (mitchdz)]

I didn't see a bug to track the Oracular merge, so I made it here https://bugs.launchpad.net/ubuntu/+source/nbd/+bug/2064688

[Andreas Hasenack (ahasenack)]

Uploaded to oracular:
Uploading nbd_3.26.1-1ubuntu1.dsc
Uploading nbd_3.26.1-1ubuntu1.debian.tar.xz
Uploading nbd_3.26.1-1ubuntu1_source.buildinfo
Uploading nbd_3.26.1-1ubuntu1_source.changes

[Launchpad Janitor (janitor)]

This bug was fixed in the package nbd - 1:3.26.1-1ubuntu1

---------------
nbd (1:3.26.1-1ubuntu1) oracular; urgency=medium

  * d/p/0002-Set-sensible-default-for-port.patch: When no port is specified
    in nbdtab, set default to NBD_DEFAULT_PORT (i.e. "10809") to fix issue
    where "0" is assumed.
    (LP: #2060745)

 -- Mitchell Dzurick <email address hidden> Fri, 03 May 2024 23:27:15 -0700