libvirt users - Sep 2013 - Re: Help needed in simulating libvirt

Hi Eric,

Thanks for your response.
I like to know how test driver works.

In the libvirt.org for test driver it is mentioned as "It can start with a
pre-configured default config, or be given a path to an alternate config".
Is the config is an xml file where we mentioned some dummy data so that the
test driver will return it as response. If yes then where can I find this
dummy file?

As mentioned earlier my intention is to mock qemu calls. so it test driver
works then I'm planning to remove the qemu driver and register
"test"
driver as "qemu" driver and take the fake data from the config file.
Please
let me know which are the files I need to look into to register "test"
as
"qemu" and make its operations to work.

Thanks In Advance,
Arun V


On Wed, Sep 11, 2013 at 12:14 AM, Eric Blake <eblake@redhat.com> wrote:
> On 09/10/2013 12:03 PM, Arun Viswanath wrote:
> > Hi All,
> >    I'm need to simulate libvirt API's say to mock the libvirt
API
> > responses. (Actually I need to simulate qemu API's response).
Because of
> my
> > project needs I need to write this simulated libvirt server in Java. I
> > believe the simulated libvirt can be written as java RPC which should
> > capable to receive the client RPC request calls and by dispatcher we
can
> > dispatch to the simulated java functions. I searched for .x file to be
> used
> > for generating server stubs but unfortunately .x files like
> > "remote_protocol.x", "virnetprotocol.x",
"qemu_protocol.x" and
> > "lxc_monitor_protocol.x" are not containing any procedure
for libvirt
> API's
> > that exposed. Please let me know which files will have these exposed
> > procedures and how can I use it in java,
>
> Rather than trying to write your own RPC handler, have you considered
> using the existing libvirt-java bindings and just targetting the
> test:/// URI connection?  This will give you a fairly reliable exposure
> to the libvirt APIs, without actually needing a working qemu.
>
> The .x files implement the driver API; so also does the test driver.
> Basically, src/libvirt.c is the public API, which then delegates to the
> appropriate driver based on what URI you connected to; if the URI is
> remote (as qemu:/// and all other stateful drivers are), then libvirt.so
> passes it to src/remote/remote_driver.c to be bundled up into RPC calls
> which mirror the semantics of the public API.  If you want to install
> your own mock driver, it may be easier to build a new URI and implement
> the same C interface as the test driver (see src/test/test_driver.c)
> than it is to implement your own RPC parser.
>
> >
> >          Also I'm not sure how to implement the ssl layer support
for the
> > libvirt server in java. I need to write a java server in such a way
that
> > python client should capable to create a connection with uri
> > "qemu+tls://systemip:port?no_tty=1". Also with the created
connection
> > object it should able to call the libvirt API's like
getCapabilities,
> etc.
>
> Again, instead of trying to write your own RPC server, I'd instead
focus
> on utilizing the existing test:/// driver as your point of mocked calls.
>
> As this is mostly development-related, I've set the reply-to to
> libvir-list (we can drop libvirt-users from the rest of this thread).
>
> --
> Eric Blake   eblake redhat com    +1-919-301-3266
> Libvirt virtualization library http://libvirt.org
>
>

On Wed, Sep 11, 2013 at 12:50:37PM +0530, Arun Viswanath
wrote:
> Hi Eric,
> 
> Thanks for your response.
> I like to know how test driver works.
> 
> In the libvirt.org for test driver it is mentioned as "It can start
with a
> pre-configured default config, or be given a path to an alternate
config".
> Is the config is an xml file where we mentioned some dummy data so that the
> test driver will return it as response. If yes then where can I find this
> dummy file?
> 
> As mentioned earlier my intention is to mock qemu calls. so it test driver
> works then I'm planning to remove the qemu driver and register
"test"
> driver as "qemu" driver and take the fake data from the config
file. Please
> let me know which are the files I need to look into to register
"test" as
> "qemu" and make its operations to work.
The XML file is provided via the URI. For example

   test:///default

uses a built-in config, but you can supply a real path eg

   test:///home/berrange/testnode.xml


Take a look at examples/xml/test/testnode.xml  in the libvirt source
tree for an example.

FYI, the test driver is used very successfully in virt-install and
virt-manager for testing their functionality in an automated way,
so I can strongly recommend its use, over trying to mock the APIs
or wire protocol yourself.

Daniel
-- 
|: http://berrange.com      -o-    http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org              -o-             http://virt-manager.org :|
|: http://autobuild.org       -o-         http://search.cpan.org/~danberr/ :|
|: http://entangle-photo.org       -o-       http://live.gnome.org/gtk-vnc :|

Hi,

Thanks for the response.

I've used the URI:
"test+ssh://<ipaddress>/default" and the connection is
successful and with
that connection I issued getCapabilities and its result is attached.
I'm not sure how is result xml generated by the files in the /examples
folder.
Will you please explain how is this xml generated.

Also my client is not going to modified. My client is going to connect with
the URI "qemu+tls://<host>/system?no_tty=1", so I can't
directly use the
test driver here so I need to replace the qemu driver with the test driver
and give my dummy response. So I need to know how to replace the driver say
qemu with test driver and generating my desired output.

If the test driver is not going to support me too much then I might want to
write new driver. Is there is any reference how to write new driver.

Regards,
Arun V


On Wed, Sep 11, 2013 at 2:23 PM, Daniel P. Berrange
<berrange@redhat.com>wrote:
> On Wed, Sep 11, 2013 at 12:50:37PM +0530, Arun Viswanath wrote:
> > Hi Eric,
> >
> > Thanks for your response.
> > I like to know how test driver works.
> >
> > In the libvirt.org for test driver it is mentioned as "It can
start
> with a
> > pre-configured default config, or be given a path to an alternate
> config".
> > Is the config is an xml file where we mentioned some dummy data so
that
> the
> > test driver will return it as response. If yes then where can I find
this
> > dummy file?
> >
> > As mentioned earlier my intention is to mock qemu calls. so it test
> driver
> > works then I'm planning to remove the qemu driver and register
"test"
> > driver as "qemu" driver and take the fake data from the
config file.
> Please
> > let me know which are the files I need to look into to register
"test" as
> > "qemu" and make its operations to work.
>
> The XML file is provided via the URI. For example
>
>    test:///default
>
> uses a built-in config, but you can supply a real path eg
>
>    test:///home/berrange/testnode.xml
>
>
> Take a look at examples/xml/test/testnode.xml  in the libvirt source
> tree for an example.
>
> FYI, the test driver is used very successfully in virt-install and
> virt-manager for testing their functionality in an automated way,
> so I can strongly recommend its use, over trying to mock the APIs
> or wire protocol yourself.
>
> Daniel
> --
> |: http://berrange.com      -o-   
http://www.flickr.com/photos/dberrange/:|
> |: http://libvirt.org              -o-            
http://virt-manager.org:|
> |: http://autobuild.org       -o-        
http://search.cpan.org/~danberr/:|
> |: http://entangle-photo.org       -o-      
http://live.gnome.org/gtk-vnc:|
>