libvirt users - Apr 2016 - Re: Libvirtd running as root tries to access oneadmin (OpenNebula) NFS mount but throws: error: can’t canonicalize path

Hi everyone,

If a VM is configured to have a console attached to it, like using

http://libvirt.org/formatdomain.html#elementCharConsole

Libvirt offers access to VM serial console's using the virDomainOpenConsole
API[1]
However, I didn't find a way to
1. list the existing connections to the console
2. kill an existing connection - without reconnecting using
VIR_DOMAIN_CONSOLE_FORCE[2]

Am I missing something? How can I do that?

Rationale for my request
oVirt [3] offers a management interface for VMs, and we have recently integrated
user-friandly
VM serial console access [4] in the system; in the future release we want to
enhance the administation
capabilities allowing to check existing connections and to terminate them (maybe
because it got stuck).

+++

[1] http://libvirt.org/html/libvirt-libvirt-domain.html#virDomainOpenConsole
[2] http://libvirt.org/html/libvirt-libvirt-domain.html#VIR_DOMAIN_CONSOLE_FORCE
[4] http://www.ovirt.org/
[5]
https://www.ovirt.org/develop/release-management/features/engine/serial-console/
et. al.

-- 
Francesco Romani
RedHat Engineering Virtualization R & D
Phone: 8261328
IRC: fromani

Hey All,

I've an issue where libvirtd tries to access an NFS mount but errors out 
with: can't canonicalize path '/var/lib/one//datastores/0 .  The 
unprevilidged user is able to read/write fine to the share. root_squash 
is used and for security reasons no_root_squash cannot be used.

On the controller and node SELinux is disabled.

[oneadmin@mdskvm-p01 ~]$ virsh -d 1 --connect qemu:///system create 
/var/lib/one//datastores/0/38/deployment.0
create: file(optdata): /var/lib/one//datastores/0/38/deployment.0
error: Failed to create domain from 
/var/lib/one//datastores/0/38/deployment.0
error: can't canonicalize path
'/var/lib/one//datastores/0/38/disk.1':
Permission denied

I added some debug flags to get more info and added -x to the deploy 
script. Closest I get to more details is this:

2016-04-06 04:15:35.945+0000: 14072: debug : 
virStorageFileBackendFileInit:1441 : initializing FS storage file 
0x7f6aa4009000 (file:/var/lib/one//datastores/0/38/disk.1)[9869:9869]
2016-04-06 04:15:35.954+0000: 14072: error : 
virStorageFileBackendFileGetUniqueIdentifier:1523 : can't canonicalize 
path '/var/lib/one//datastores/0/38/disk.1':

https://www.redhat.com/archives/libvir-list/2014-May/msg00194.html

Comment is: "The current implementation works for local
storage only and returns the canonical path of the volume."

But it seems the logic is applied to NFS mounts. Perhaps it shouldn't 
be?  Anyway to get around this problem?  This is CentOS 7 .

Cheers,
Tom K.
-------------------------------------------------------------------------------------

Living on earth is expensive, but it includes a free trip around the sun.

On Thu, Apr 07, 2016 at 08:26:20 -0400, Francesco Romani
wrote:
> Hi everyone,
> 
> If a VM is configured to have a console attached to it, like using
> 
> http://libvirt.org/formatdomain.html#elementCharConsole
> 
> Libvirt offers access to VM serial console's using the
virDomainOpenConsole API[1]
> However, I didn't find a way to
> 1. list the existing connections to the console
> 2. kill an existing connection - without reconnecting using
VIR_DOMAIN_CONSOLE_FORCE[2]
> 
> Am I missing something? How can I do that?
Neither of those is possible currently.
> 
> Rationale for my request
> oVirt [3] offers a management interface for VMs, and we have recently
integrated user-friandly
> VM serial console access [4] in the system; in the future release we want
to enhance the administation
> capabilities allowing to check existing connections and to terminate them
(maybe because it got stuck).
I think the plan that danpb has in this aspect is to use virlogd to
distribute the console output to almost any number of clients, which
would solve this kind of problem.

Additionally, doesn't oVirt use just one connection from VDSM for this
purpose. In that case it's rather trivial to know which connection
(to libvirt) has currently opened console stream. ;)

Peter

Adding in libvir-list.

Cheers,
Tom K.
-------------------------------------------------------------------------------------

Mobile: 416 618 8456
Home: 905 857 9652
Living on earth is expensive, but it includes a free trip around the sun.

On 4/7/2016 7:32 PM, TomK wrote:
> Hey All,
>
> I've an issue where libvirtd tries to access an NFS mount but errors 
> out with: can't canonicalize path '/var/lib/one//datastores/0 . 
The
> unprevilidged user is able to read/write fine to the share. 
> root_squash is used and for security reasons no_root_squash cannot be 
> used.
>
> On the controller and node SELinux is disabled.
>
> [oneadmin@mdskvm-p01 ~]$ virsh -d 1 --connect qemu:///system create 
> /var/lib/one//datastores/0/38/deployment.0
> create: file(optdata): /var/lib/one//datastores/0/38/deployment.0
> error: Failed to create domain from 
> /var/lib/one//datastores/0/38/deployment.0
> error: can't canonicalize path
'/var/lib/one//datastores/0/38/disk.1':
> Permission denied
>
> I added some debug flags to get more info and added -x to the deploy 
> script. Closest I get to more details is this:
>
> 2016-04-06 04:15:35.945+0000: 14072: debug : 
> virStorageFileBackendFileInit:1441 : initializing FS storage file 
> 0x7f6aa4009000 (file:/var/lib/one//datastores/0/38/disk.1)[9869:9869]
> 2016-04-06 04:15:35.954+0000: 14072: error : 
> virStorageFileBackendFileGetUniqueIdentifier:1523 : can't canonicalize 
> path '/var/lib/one//datastores/0/38/disk.1':
>
> https://www.redhat.com/archives/libvir-list/2014-May/msg00194.html
>
> Comment is: "The current implementation works for local
> storage only and returns the canonical path of the volume."
>
> But it seems the logic is applied to NFS mounts. Perhaps it shouldn't 
> be?  Anyway to get around this problem?  This is CentOS 7 .
>
> Cheers,
> Tom K.
>
-------------------------------------------------------------------------------------
>
> Living on earth is expensive, but it includes a free trip around the sun.
>
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