Bug 1692608

The behavior is expected when you restart virtlogd in general. If there are changed to virtlogd on a life system, a signal can be send to the process to keep the current logs open instead of a full restart:

~~~
On receipt of SIGUSR1 virtlogd will re-exec() its binary, while maintaining all current logs and clients. This allows for live upgrades of the virtlogd service.
~~~

What is the use case? Updating a compute node where we get a new container version with virtlogd? If yes, then the instances should be migrated off the compute before upgrading the compute.

Dan,

from virtlogd/libvirtd site, is there anything which can be done to reopen the console logs when virtlogd gets restarted? For non container envs you could send the signal as mentioned in my last update, but when updating containers this won't work.

Thanks!

No, this is explicitly *NOT* supported. The virtlogd daemon must *never* be stopped while there are running VMs. It is explicitly split out into a separate daemon from libvirtd so that it can upgrade its own software while keeping FDs open by re-exec'ing itself. If running virtlogd in a container this container must never be restarted while VMs are running.

AFAIK this shouldn't be a problem on OSP in general, as the recommended software upgrade process involves live migrating all VMs off to a new host, before upgrading any of the containers / software on the original host.

To me it sounds like virtlogd should not be managed by paunch at all, and it should be treated in a similar way to the neutron l3[1] and dhcp[2] agents.

I'll set a NEEDINFO for beagles to provide an opinion on whether the wrapper approach is appropriate for virtlogd, and how it might be done.

[1] https://github.com/openstack/puppet-tripleo/blob/master/manifests/profile/base/neutron/l3_agent_wrappers.pp
    https://github.com/openstack/tripleo-heat-templates/blob/master/deployment/neutron/neutron-l3-container-puppet.yaml#L172-L186
[2] https://github.com/openstack/puppet-tripleo/blob/master/manifests/profile/base/neutron/dhcp_agent_wrappers.pp
    https://github.com/openstack/tripleo-heat-templates/blob/master/deployment/neutron/neutron-dhcp-container-puppet.yaml

If there were a per-vm process for virtlogd, neutron-esque sidecars could be the way to go. Even if it were a single process, sidecar containers would also remove the interaction with updates etc. However, we do this kind of thing in neutron because of the relationship between openstack resources and processes and the desire to preserve the data plane at all costs. If there is a 1:1 relationship between libvirtd and virtlogd and virtlogd doesn't like being restarted containers or not, I'm not sure that neutron-like sidecars are appropriate

Guys,   what if we want to change the max_size for logs and restart virtlogd on servers with SR-IOV nics (or any pci_passthrough) ... 
Is there any technical reasons that would prevent us from reloading virtlogd with some code improvment ?

If we absolutely have to reboot after restarting virtlogd, I guess we'll have to update this KCS article [1] to mention this ...

[1] https://access.redhat.com/solutions/3293321

TRAC team have stated there will be no RFEs in zstreams for OSP 17.0 so moving this to 17.1. Any questions please contact rhos-trac.

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (Release of components for Red Hat OpenStack Platform 17.1 (Wallaby)), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHEA-2023:4577