[Libguestfs] Question how to implement remote access

[Richard W.M. Jones]

On Wed, Jan 06, 2016 at 01:09:27PM +0900, BYEONG-GI KIM wrote:
> Hello.
> 
> I've been finding a good solution to monitor virtual machines' status such
> as memory, disk, cpu, etc, and I found this as a tool for measuring
> disk/image status.
> 
> I have a question while using the libguestfs-java library; I'd wanted to
> implement a sample app which retrieve the disk information remotely. Is
> there any way, i.e., specific API(s) to connect with a host where kvm/qemu
> has been installed from a remote node, to access and get VMs' disk related
> information remotely?
> 
> I read JavaDoc and libguestfs-java sample code from
> http://libguestfs.org/guestfs-java.3.html, but I could not find such an
> example.

It's a good question actually.  Using a remote libvirt connection will
*not* work.  Unless your disks are on shared storage, and are
accessible using the same paths at the monitoring machine, in which
case it might work.

[To see if this could work, try doing the following command from the
monitoring machine:

  virsh -c qemu+ssh://root@hypervisor.example.com/system dumpxml name_of_a_guest

and if the command works and the paths in the returned libvirt XML are
also valid on the local monitoring machine, then libguestfs may work
remotely.]

I suggest that you use a Java remoting library such as RMI,
SpringSource remoting, JBoss remoting or others.  It does mean that
you'll need to run a small service (the Java RMI server) on each node.

You can see a similar idea -- but implemented in Python -- here:

  https://rwmj.wordpress.com/2013/05/07/using-libguestfs-remotely-with-python-and-rpyc/

Another useful answer may be this one:

  https://www.redhat.com/archives/libguestfs/2011-May/msg00093.html

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
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