[libvirt] First mail & (long) question

[Michal Privoznik]

On 13.12.2013 19:21, Joaquim Barrera wrote:
> Hello everybody!
> 
> I would like to introduce myself, as this is my first contact with
> libvirt mailing list (although I've been reading quite a lot of
> documentation).
> 
> My name is Joaquim Barrera, from Barcelona, Catalonia. I am a computer
> engineer and recently I joined a research group here in the university.
> My task is related to VM migration and management, and since then (a
> couple of months) I've been trying to figure some things up.
> 
> Now I need to go one step forward, and I would like to set up a nice dev
> environment to try some modifications we want to make to libvirt, such
> as new API or migration-related-stuff.
> 
> Although I am familiar with linux environrment and programming, I am not
> really quite familiar with this kind of, may I say, professional
> development, and there are some issues I need to solve before start
> writting code. Some of this issues you'll find not relevant or newbie
> stuff, but I assure you I tried lots of times before coming here. :-)
> 
> Here is what I got following the instructions in
> http://libvirt.org/compiling.html
> 
>       $ ./autogen.sh --system
>       $ make
> 
> 
> After make finishes I have compiled 1.2.0 libvirt in the source tree,
> and if I execute 'sudo ./run tools/virsh version' I get a this answer:
> 
> /Compiled against library: libvirt 1.2.0//
> //Using library: libvirt 1.2.0//
> //Using API: QEMU 1.2.0//
> //Running hypervisor: QEMU 1.5.0/
> 
> (note that now I need to run virsh with sudo, I don't know exactly why)
> 
> So far, so good. I guess that, with --system flag, 1.2.0 custom libvirt
> uses config files from standard directories such as
> /etc/libvirt/libvirtd.conf, and if I used a custom directory instead, I
> would have to redefine my VMs, am I right?

Yes. The '--system' just passes --prefix --sysconfdir and others. So if
you don't use the '--system' argument you'll end up with a different
config dir where the libvirtd is searching for domain configs.

> 
> Problems come when I want to use custom 1.2.0 daemon. If I execute "sudo
> service libvirt-bin stop" followed by "./daemon/libvirtd -d", then
> custom virsh gives me this error:
> 
> /error: failed to connect to the hypervisor//
> //error: no valid connection//
> //error: Failed to connect socket to '/var/run/libvirt/libvirt-sock': No
> such file or directory/

I believe the daemon you've built died for some reason. You can try
running it without the '-d' and it should print some error in the
console if my assumption is right. Or look into /var/log/messages what
has been logged there (or whatever log dst you've set).

In general, we strive and thrive in keeping virsh able to communicate
with whatever libvirtd out there.

Michal