On 09/03/2012 10:33 PM, Dan Kenigsberg wrote:
On Thu, Aug 30, 2012 at 04:26:31PM -0500, Adam Litke wrote:
On Thu, Aug 30, 2012 at 11:32:02AM +0800, Xu He Jie wrote:
Hi,
I submited a patch for text-based console
http://gerrit.ovirt.org/#/c/7165/
the issue I want to discussing as below:
1. fix port VS dynamic port
Use fix port for all VM's console. connect console with 'ssh
vmUUID@ip -p port'.
Distinguishing VM by vmUUID.
The current implement was vdsm will allocated port for console
dynamically and spawn sub-process when VM creating.
In sub-process the main thread responsible for accept new connection
and dispatch output of console to each connection.
When new connection is coming, main processing create new thread for
each new connection. Dynamic port will allocated
port for each VM and use range port. It isn't good for firewall rules.
so I got a suggestion that use fix port. and connect console with
'ssh vmuuid@hostip -p fixport'. this is simple for user.
We need one process for accept new connection from fix port and when
new connection is coming, spawn sub-process for each vm.
But because the console only can open by one process, main process
need responsible for dispatching console's output of all vms and all
connection.
So the code will be a little complex then dynamic port.
So this is dynamic port VS fix port and simple code VS complex code.
>From a usability point of view, I think the fixed port suggestion is nicer.
This means that a system administrator needs only to open one port to enable
remote console access. If your initial implementation limits console access to
one connection per VM would that simplify the code?
Yes, using a fixed port for all consoles of all VMs seems like a cooler
idea. Besides the firewall issue, there's user experience: instead of
calling getVmStats to tell the vm port, and then use ssh, only one ssh
call is needed. (Taking this one step further - it would make sense to
add another layer on top, directing console clients to the specific host
currently running the Vm.)
I did not take a close look at your implementation, and did not research
this myself, but have you considered using sshd for this? I suppose you
can configure sshd to collect the list of known "users" from
`getAllVmStats`, and force it to run a command that redirects VM's
console to the ssh client. It has a potential of being a more robust
implementation.
I have considered using sshd and ssh tunnel. They
can't implement fixed port and share console. Current implement
we can do anything that what we want.
We may want to start thinking about migration. It would be great if we
could have a smart console client that connects to the source and
destination consoles, and moves to the destination on-line, without
loosing a character.
This is interesting. My first thinking is it's easy implement at client
side. I think we will implement ssh client in webbrowser. Engine will
know the vm was migrated. Engine can tell client reconnect console to
another host. I will try to think about is there any better idea.
Regards,
Dan.
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