Fuel for OpenStack

Resuming instance in suspend state clears out instance console.log

Bug #1503324 reported by Javier Diaz Jr
18
This bug affects 3 people
Affects Status Importance Assigned to Milestone
Fuel for OpenStack
Won't Fix
Medium
MOS Nova
Fuel for OpenStack 8.0
6.1.x
Won't Fix
Medium
MOS Maintenance
Fuel for OpenStack 6.1-updates
7.0.x
Won't Fix
Medium
MOS Maintenance
Fuel for OpenStack 7.0-updates

Bug Description

A user has reported that they are able to see the console lot output for their instances when they are in active and suspend status. However, as soon as the instance is resumed from the suspend status the console.log clears out and remains empty until a reboot is issued. The reason for this appears to be that the qemu/kvm process is stopped completely during a suspend. On resume, the console log is being truncated rather than appended.

Steps to reproduce:

1. Launch an instance with any image (I used Cirros).

2. Check log and you will find normal output (i.e. cubswin..)

3. Execute suspend command on instance.

4. Check log again and you will find the same normal output.

5. Execute resume command on instance.

6. You will find that the console log is now empty.

Workaround:

1. Soft or Hard Reboot instance.

2. Console Log returns.

Veronica Krayneva (vkrayneva)
Changed in fuel:
assignee: nobody → MOS Nova (mos-nova)
milestone: none → 8.0
importance: Undecided → Medium
Roman Podoliaka (rpodolyaka)
Changed in fuel:
status: New → Confirmed
Dmitry Pyzhov (dpyzhov)
tags: added: area-mos
Daniil Lapshin (dlapshin)
tags: added: customer-found
Revision history for this message
AntonioK (rc5hack) wrote :

I reproduce this in both 6.1 and 7.0.

Revision history for this message
Evgeny Kozhemyakin (ekozhemyakin) wrote :

A customer asks for a fix/workarond so I set High.

Changed in fuel:
importance: Medium → High
Revision history for this message
Roman Rufanov (rrufanov) wrote :

customer found on 7.0 need fix.

tags: added: support
Revision history for this message
Roman Rufanov (rrufanov) wrote :

related to https://bugs.launchpad.net/nova/+bug/1083692

Dmitry Pyzhov (dpyzhov)
no longer affects: fuel/8.0.x
Revision history for this message
Roman Podoliaka (rpodolyaka) wrote :

Roman, it's not related, it's the very same issue.

Revision history for this message
Denis Meltsaykin (dmeltsaykin) wrote :

Closing this as Won't Fix for updates branches, as this is not a bug, this is correct behaviour of libvirt/qemu.

Revision history for this message
Roman Podoliaka (rpodolyaka) wrote :

I took a look at this on my 8.0 deployment and can confirm that analysis done in https://bugs.launchpad.net/nova/+bug/1083692 is correct, except for the fact that it's qemu (https://github.com/qemu/qemu/blob/master/qemu-char.c#L4091-L4115) which opens and truncates the file, not libvirt.

Rafi Khardalian suggested two solutions for this:

1) add support for appending to the console log to qemu / libvirt

2) hack this on Nova side and modify the console log after qemu process is started on resume

The latter seems to be a rather ugly hack, which is not going to be accepted by upstream, so we risk ending up supporting this on our own in each subsequent release of MOS. I'm strongly against doing this in downstream.

The former sounds better, but the problem is that it will take time to implement this enhancement in qemu / libvirt. And I assume they also have strict policy on what can and what can not be backported to previous releases. Linux distributions are somewhat conservative on qemu / libvirt versions used, so I don't expect this to come to MOS any time soon.

Changed in fuel:
status: Confirmed → Won't Fix
Roman Podoliaka (rpodolyaka)
tags: added: enhancement
Vitaly Sedelnik (vsedelnik)
tags: added: wontfix-feature
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