Re: [Kimchi-devel] RFC: Add serial as a valid graphics type

on 2014/10/15 12:10, Zhou Zheng Sheng wrote: > on 2014/10/14 21:45, Aline Manera wrote: >> On 10/14/2014 07:04 AM, Yu Xin Huo wrote: >>> https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/... >>> >>> >>> Per my understanding: >>> >>> 1. To enable the serial console, it needs configuration on guest OS. >>> >>> / You must configure the virtualized operating system to output >>> information to the virtual serial port.// >>> // The serial port is called //|ttyS0|//on Linux or >>> //|COM1|//on Windows./ >>> >>> It need to modify the |/boot/grub/grub.conf| file on guest OS and >>> reboot guest. >>> >>> So VM must have OS already installed, seems like it needs the >>> guest to be running. >> Prior to do that guest OS configuration, the guest must have the serial >> console set on its XML. >> >> <serial type='pty'> >> <target port='0'/> >> </serial> >> <console type='pty'> >> <target type='serial' port='0'/> >> </console> >> > I found that Fedora can scan and use ttyS0 as terminal > automatically, so save the user from manually editing grub config. This > is not often used, but it's handy when troubleshooting, or when the > network is too slow to support an VNC/Spice session. > >> So the idea is providing a way to user to choose between spice, vnc or >> serial and Kimchi will setup the guest XML accordingly. >> > However I don't think spice/vnc and serial are exclusive options. Spice > and VNC are alternative to each other but serial should be a complement, > mainly for troubleshooting. If a newly created guest doesn't have > spice/vnc, and only contains serial port, it may not be able to install > OS successfully, because not all Linux installation programme support > serial console mode. Since the user has to modify kernel argument before > using a serial port, if without vnc/spice, how can user edit the kernel > argument. > > It's true the real servers does not have display and keyboard, but the > admin can use KVM (Keyboard Video Mouse facilities) to connect to the > server video display, or use something like IMM on IBM X servers. > > I notice that by default, guest created by virt-manager contains a > serial port. I think we can follow the same idea. We could always > provide vnc/spice and serial port. vnc/spice is for main use, serial > port is for troubleshooting. > >> For reference: >> - >> http://rwmj.wordpress.com/2011/07/08/setting-up-a-serial-console-in-qemu-... >> >> - http://libvirt.org/formatdomain.html#elementsConsole >> >>> 2. The serial console can be accessed with 'virsh console' or 'use >>> |virt-manager| to display the virtual text console'. >>> >>> So the target of this work item is to add a 'web command line >>> console' in kimchi UI to access the 'serial console'? >>> >>> |||| >> We could try to find an AJAX text console to enable serial console view >> direct on Kimchi (the same virt-manager does) >> So if the guest is configured with serial console and user clicks on >> "Connect" we open the text console in a new tab. >> But unless we find this AJAX text console done in an open source >> project, I don't expect to have it for 1.4 release. >> > I found that in websockify source code, there is a wspty. It is a > terminal implemented in HTML and js. I was once in oVirt community, at > that time I was able to build a serial console solution using this > wspty. However I found that there some bugs, some keys are not > interpreted correctly. Maybe we can have a look at this wspty? If it's > good we can submit bug fixes to websockify. > > The console solution once I implemented was like this. > guest serial port -> qemu char devices -> host pty > > Then I made a proxy to open this pty and forward the data to an HTTP > long connecion. > host pty -> proxy ---(HTTP)--> wspty > > wspty is using websocket, I changed it a little bit to use raw HTTP instead. > > For this part, I have a prototype repository on github, maybe you can > have a look. There are instructions on how to setup a guest and using a > proxy and wspty to access it's serial port. > > https://github.com/edwardbadboy/ptyforward/blob/master/README Ha ha, I just found in this repository, I also wrote an websocket proxy to forward pty to websocket. The websocket and web server was based on ws4py + WSGI + gevent, in just 113 lines of Python. This repository is too old I almost forget it.

> If we are to use websocket, the nature solution would be as follow > host pty -> websockify ---(websocket)--> wspty > > There is a potential security risk. If we use websockify to transfer > serial port data, we are exposing the serial port to public without any > authentication. We have the same problem in VNC/Spice, that's why we add > ticket. The VNC ticket is using the password mechanism built in the VNC > protocol. However when using serial port, there is no such protocol, it > just transfers raw data. A solution is that we use the websocket > facility supported by cherrypy and forward the serial port data > ourselves, so that we can do authentication as usual.