On 21.05.2015 12:33, Umer Khan wrote:

Hi all,

I am new to libvirt, I am trying to execute some commands inside guest domains from my host machine using libvirt-Python API. So far I have been able to open up a stream but I am not sure how to send commands on the stream (through virDomainOpenConsole). After hours of searching through different forums I found out that there is a utlity called qemu-guest agent which can solve my problem. But I am not sure how to enable this agent on host and domain, and how this will be used to communicate to guest domains. Any help in this matter will be really appreciated.

Thanks

http://wiki.libvirt.org/page/Qemu_guest_agent After you've set up the guest agent (both in libvirt and in guest), you can passtrhough an arbitrary guest agent commands too: http://git.qemu.org/?p=qemu.git;a=blob;f=qga/qapi-schema.json;h=b446dc729dc1... Although I should warn you that qemu-ga does not allow arbitrary OS command execution. To do that you'd need to use a console. I think virsh is a good example on that: http://libvirt.org/git/?p=libvirt.git;a=blob;f=tools/virsh-console.c;h=f0faf... Long story short, you create a new stream @st by calling virStreamNew(). Then you open a console and connect the stream onto it: virDomainOpenConsole(dom, dev_name, st, flags); then you register two events into the event loop, one to watch if STDIN is readable (= has some data to send = somebody typed something), the other to watch if STDOUT is writable (it can be redirected to a file or whatever, which is not necessarily always writable). The third event you register is to handle the stream. This is the idea: streamEvent() { if (stream_readable) { read data from stream into terminal buffer make STDOUT handler listen to writable event } if (stream_writable and stream buffer != empty) { send data to stream from stream buffer } if (terminal buffer == empty) make stream handler listen to readable event } stdin_event() { read data from STDIN into stream buffer make stream handler listen to readable | writable event } stdout_event() { write data from terminal buffer to STDOUT if (terminal buffer == empty) temporarily disable stdout handler } I hope this makes it something clearer. Michal