8:26 a.m.
I am trying to change a domain configuration from a python script. More
specific, I want to edit the VNC settings. You can't do this using the
libvirt API so you have to edit the domain configuration:
Fo exmple, to disable VNC for a domain 'test1':
vmXml = vm.XMLDesc(0)
root = ET.fromstring(vmXml)
devices = root.find('./devices')
graphics = devices.find('graphics')
devices.remove(graphics)
xml = ET.tostring(root)
with open('path_to/test1.xml', 'w') as f:
f.write(xml)
not the problem is with the test1.xml. Even though the domain configuration
seems to be stored there, the file seems to be regenerated/overwritten so
any changes I make will not take effect.
So the question really is: where is the domain configuration stored? Am I
editing the write file, or am I missing something?
Thanks,
Andrei
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Klas Telecom Inc., a Virginia Corporation with offices at 1101 30th St. NW,
Washington, DC 20007.
Klas Limited (Company Number 163303) trading as Klas Telecom, an Irish
Limited Liability Company, with its registered office at Fourth Floor, One
Kilmainham Square, Inchicore Road, Kilmainham, Dublin 8, Ireland.
11:25 a.m.
On 12/11/2015 07:26 AM, Andrei Perietanu wrote:
I am trying to change a domain configuration from a python script.
More
specific, I want to edit the VNC settings. You can't do this using the
libvirt API so you have to edit the domain configuration:
Umm, the libvirt API _is_ how you edit the domain configuration.
Fo exmple, to disable VNC for a domain 'test1':
vmXml = vm.XMLDesc(0)
root = ET.fromstring(vmXml)
devices = root.find('./devices')
graphics = devices.find('graphics')
devices.remove(graphics)
xml = ET.tostring(root)
with open('path_to/test1.xml', 'w') as f:
f.write(xml)
Writing to path_to/test1.xml is not necessary (it's merely a convenient
way for you to have a point-in-time snapshot of what the domain XML
was); what you are really looking for is to write the XML back to
libvirt, via:
vm.defineXML(xml)
So the question really is: where is the domain configuration stored?
Am I
editing the write file, or am I missing something?
The official copy is stored in memory, so the only supported way to
manipulate it is via libvirt API. Libvirt happens to copy its memory
into files located under /etc/libvirt for persistence reasons, but
modifying those files behind libvirt's back is not a good idea - in
fact, those files start with the disclaimer:
<!--
WARNING: THIS IS AN AUTO-GENERATED FILE. CHANGES TO IT ARE LIKELY TO BE
OVERWRITTEN AND LOST. Changes to this xml configuration should be made
using:
virsh edit domain
or other application using the libvirt API.
-->
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
3:36 a.m.
Tanks for the reply Eric.
The only reason I'm not going through the API is because there is nothing
in the API (AFIK), that will allow you to modify the VNC settings, i.e.
enable/disable, change port number. So I figured, the only way to do it is
to modify the XML.
I can't use virsh edit because I need this whole behavior scripted.
So now if I want to change the VNC settings it looks like I have to read
the XML, modify it, define it, actually re-define it (maybe I have to
undefine it first?! ) and that's it - correct?
Andrei
On Fri, Dec 11, 2015 at 5:25 PM, Eric Blake <eblake(a)redhat.com> wrote:
On 12/11/2015 07:26 AM, Andrei Perietanu wrote:
> I am trying to change a domain configuration from a python script. More
> specific, I want to edit the VNC settings. You can't do this using the
> libvirt API so you have to edit the domain configuration:
Umm, the libvirt API _is_ how you edit the domain configuration.
>
> Fo exmple, to disable VNC for a domain 'test1':
>
> vmXml = vm.XMLDesc(0)
> root = ET.fromstring(vmXml)
> devices = root.find('./devices')
> graphics = devices.find('graphics')
> devices.remove(graphics)
> xml = ET.tostring(root)
> with open('path_to/test1.xml', 'w') as f:
> f.write(xml)
Writing to path_to/test1.xml is not necessary (it's merely a convenient
way for you to have a point-in-time snapshot of what the domain XML
was); what you are really looking for is to write the XML back to
libvirt, via:
vm.defineXML(xml)
> So the question really is: where is the domain configuration stored? Am I
> editing the write file, or am I missing something?
The official copy is stored in memory, so the only supported way to
manipulate it is via libvirt API. Libvirt happens to copy its memory
into files located under /etc/libvirt for persistence reasons, but
modifying those files behind libvirt's back is not a good idea - in
fact, those files start with the disclaimer:
<!--
WARNING: THIS IS AN AUTO-GENERATED FILE. CHANGES TO IT ARE LIKELY TO BE
OVERWRITTEN AND LOST. Changes to this xml configuration should be made
using:
virsh edit domain
or other application using the libvirt API.
-->
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
--
The information transmitted is intended only for the person or entity to
which it is addressed and may contain confidential and/or privileged
material. Any review, retransmission, dissemination or other use of or
taking of any action in reliance upon this information by persons or
entities other than the intended recipient is prohibited. If you receive
this in error please contact the sender and delete the material from any
computer immediately. It is the policy of Klas Limited to disavow the
sending of offensive material and should you consider that the material
contained in the message is offensive you should contact the sender
immediately and also your I.T. Manager.
Klas Telecom Inc., a Virginia Corporation with offices at 1101 30th St. NW,
Washington, DC 20007.
Klas Limited (Company Number 163303) trading as Klas Telecom, an Irish
Limited Liability Company, with its registered office at Fourth Floor, One
Kilmainham Square, Inchicore Road, Kilmainham, Dublin 8, Ireland.
3:50 p.m.
On 12/15/2015 04:36 AM, Andrei Perietanu wrote:
Tanks for the reply Eric.
The only reason I'm not going through the API is because there is
nothing in the API (AFIK), that will allow you to modify the VNC
settings, i.e. enable/disable, change port number. So I figured, the
only way to do it is to modify the XML.
I can't use virsh edit because I need this whole behavior scripted.
So now if I want to change the VNC settings it looks like I have to
read the XML, modify it, define it, actually re-define it (maybe I
have to undefine it first?! ) and that's it - correct?
If you "define" a domain that already exists, the new definition
replaces the existing one, but not until the domain has been powered off
- the next time it is started, the new config takes effect. There is no
need to "undefine" or separately "re-define".
So the solution to your problem is to simply replace the final two lines
of your example code (open() and f.write()) with Eric's suggested line:
vm.defineXML(xml)
That's it.
(BTW, please make your replies inline rather that top-posting. It makes
it much easier to follow the discussion)
Andrei
On Fri, Dec 11, 2015 at 5:25 PM, Eric Blake <eblake(a)redhat.com
<mailto:eblake@redhat.com>> wrote:
On 12/11/2015 07:26 AM, Andrei Perietanu wrote:
> I am trying to change a domain configuration from a python
script. More
> specific, I want to edit the VNC settings. You can't do this
using the
> libvirt API so you have to edit the domain configuration:
Umm, the libvirt API _is_ how you edit the domain configuration.
>
> Fo exmple, to disable VNC for a domain 'test1':
>
> vmXml = vm.XMLDesc(0)
> root = ET.fromstring(vmXml)
> devices = root.find('./devices')
> graphics = devices.find('graphics')
> devices.remove(graphics)
> xml = ET.tostring(root)
> with open('path_to/test1.xml', 'w') as f:
> f.write(xml)
Writing to path_to/test1.xml is not necessary (it's merely a
convenient
way for you to have a point-in-time snapshot of what the domain XML
was); what you are really looking for is to write the XML back to
libvirt, via:
vm.defineXML(xml)
> So the question really is: where is the domain configuration
stored? Am I
> editing the write file, or am I missing something?
The official copy is stored in memory, so the only supported way to
manipulate it is via libvirt API. Libvirt happens to copy its memory
into files located under /etc/libvirt for persistence reasons, but
modifying those files behind libvirt's back is not a good idea - in
fact, those files start with the disclaimer:
<!--
WARNING: THIS IS AN AUTO-GENERATED FILE. CHANGES TO IT ARE LIKELY
TO BE
OVERWRITTEN AND LOST. Changes to this xml configuration should be made
using:
virsh edit domain
or other application using the libvirt API.
-->
--
Eric Blake eblake redhat com +1-919-301-3266 <tel:%2B1-919-301-3266>
Libvirt virtualization library http://libvirt.org
The information transmitted is intended only for the person or entity
to which it is addressed and may contain confidential and/or
privileged material. Any review, retransmission, dissemination or
other use of or taking of any action in reliance upon this information
by persons or entities other than the intended recipient is
prohibited. If you receive this in error please contact the sender and
delete the material from any computer immediately. It is the policy of
Klas Limited to disavow the sending of offensive material and should
you consider that the material contained in the message is offensive
you should contact the sender immediately and also your I.T. Manager.
Klas Telecom Inc., a Virginia Corporation with offices at 1101
30th St. NW, Washington, DC 20007.
Klas Limited (Company Number 163303) trading as Klas Telecom, an Irish
Limited Liability Company, with its registered office at Fourth Floor,
One Kilmainham Square, Inchicore Road, Kilmainham, Dublin 8, Ireland.
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3 comments
3 participants
participants (3)
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Andrei Perietanu -
Eric Blake -
Laine Stump