[Avocado-devel] Using network sniffer in avocado-vt

[Sergey Bronnikov]

ср, 12 сент. 2018 г. в 12:09, Xu Han <xuhan at redhat.com>:

>
> On 9/12/18 7:58 AM, Cleber Rosa wrote:
>
> On 9/11/18 5:43 AM, Sergey Bronnikov wrote:
>
> Hello!
>
> avocado-vt uses network sniffer (tshark or tcpdump) for getting
> IP address of running guest OS. QEMU has an option to dump network
> traffic to a file. Using this option looks simpler than using of
> external sniffer . I believe there were reasons to prefer sniffer
> instead of qemu dump option. Can someone tell about them?
>
> Sergey
>
> Sergey,
>
> It'd be nice to try to rewrite the "sniffing" code in terms of "-object
> filter-dump" (AKA "-net dump").
>
> I see that there are some limitations in the QEMU builtin network dump,
> but we can always use such an implementation when appropriate.
>
> It's a good idea to use '-net dump' functionality for getting IP
> addresses, parsing pcap format files is always be easy than parsing plain
> text generated by those sniffer tools.
>
> However, my concern is that this method is a little bit aggressive, I'm
> not sure if enabling this function  for a guest would affect the other part
> of the network function. And please be noted that a well functioning QEMU
> is the guarantee for us to get the correct IP addresses, while the QEMU is
> the box that we are testing.
>
Please take into account that there are many projects (including mine)
where Avocado-VT used not for testing QEMU but for testing software
_inside_ QEMU.


> Xu has written the tshak backend, so I bet he knows more about it.
>
> Honestly speaking, I have no idea about why it used tcpdump not others..
> The reason of adding the tshark(wireshark) support is, sometimes, tcpdump
> has the problem to get the right informaion (see
> https://github.com/avocado-framework/avocado-vt/pull/1463).
>
> We can also get IP adresses by using the function provided by
> qemu-guest-agent, it can work with both dhcp and static network. But, for
> me, it is an "aggressive" way as well.
>
This method may not work when OS inside QEMU is under test.


> Thanks,
> Xu
>
>
> FIY, we're trying a different approach of getting guest information on
> Avocado (not on Avocado-VT), by using the "cloudinit" feature when the
> guest has support for it:
> https://avocado-framework.readthedocs.io/en/64.0/api/utils/avocado.utils.html#module-avocado.utils.cloudinit
>
> It's simplistic at the moment, but it's possible to check for the
> instance id used, and get the IP address from the the "phone home" HTTP
> connection.
>
> Regards,
>
>
>
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