virsh console needs to see a pseudo-terminal and ssh doesn't create one if it is asked to execute a remote command directly. You may, however, explicitly ask ssh to create the terminal with -t option:

    ssh -t root@libvirthost virsh console myVM

Two things

 - The error reporting from virsh console here sucks
 - 'ssh -t' won't actually work, because although that lets virsh puts the remote console into rawmode, the local console is still in cooked mode. So newlines get interpreted wrongly

AFAICT, the only thing we can do is to improve the error reporting

With this patch

https://www.redhat.com/archives/libvir-list/2012-February/msg00690.html

You'll see

  $ ssh root@somehost  virsh console f16x86_64
  error: Cannot run interactive console without a controlling TTY

> - 'ssh -t' won't actually work, because although that lets virsh puts the
> remote console into rawmode, the local console is still in cooked mode. So
> newlines get interpreted wrongly

Ignore this comment, it is wrong.

Dan Y., out of curiosity, what are you trying to implement with this?

One other thought, you could also use the remote stream support to connect the console, I don't know if that requires installing stuff on the machine from which you are connecting that you're uncomfortable with.

(In reply to comment #8)
> One other thought, you could also use the remote stream support to connect the
> console, I don't know if that requires installing stuff on the machine from
> which you are connecting that you're uncomfortable with.

What do you mean by "remote stream" - to set up a socket?

I mean http://libvirt.org/html/libvirt-libvirt.html#virStreamNew and friends
that let you create a data pipe over a remote connection so you can do things
like implement a serial console for on a VM on another machine.

(In reply to comment #10)
> I mean http://libvirt.org/html/libvirt-libvirt.html#virStreamNew and friends
> that let you create a data pipe over a remote connection so you can do things
> like implement a serial console for on a VM on another machine.

Thanks, I wasn't aware of this. My current solution seems to work, and looks like it's enough for now. I suppose this will be considered as a full-fledged feature in the future

The patch fixing the error handling of that case is available in build
libvirt-0.9.10-4.el6,

Daniel

Verify this bug with :

libvirt-0.9.10-4.el6.x86_64
qemu-kvm-0.12.1.2-2.236.el6.x86_64



[ssh without -t ]:

# ssh  10.66.85.217 virsh console r
root.85.217's password: 
error: Cannot run interactive console without a controlling TTY


[ssh with -t ]:

# ssh -t 10.66.85.217 virsh console r
root.85.217's password: 
Connected to domain r
Escape character is ^]
[  OK  ]
Setting hostname virtlab-66-84-201.englab.nay.redhat.com:  [  OK  ]
Setting up Logical Volume Management:   2 logical volume(s) in volume group "vg_virtlab6684201" now active
[  OK  ]
Checking filesystems
Checking all file systems.
...

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, and where to find the updated
files, follow the link below.

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

http://rhn.redhat.com/errata/RHSA-2012-0748.html