How to get VNC port number using libvirt?

Question

I set autoport=yes in a domain's("virtual machine" in libvirt) config file so the VNC port is assigned automatically in the run time.

I need to get this port so I can connect to the vm from outside, but I can't find the proper API to do so. Better in python because I'm using the libvirt-python bindings.

score 22 · Accepted Answer · edited May 26 '15 at 12:11

22

I have not found any API for the VNC port, not sure if the newer version of libvirt has this interface?

However, you can use the command virsh vncdisplay $domainName to show the port. NOTE: you must modify /etc/libvirt/qemu.conf enable vnc_listen='0.0.0.0'.

edited May 26 '15 at 12:11

slm

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answered Nov 14 '12 at 05:29

liuzhijun

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score 7 · Answer 2 · edited May 26 '15 at 12:13

There's no API to get the VNC port. You have to take and parse the XML file to find out that port. Of course if the guest is destroyed (powered off/offline) that port will be a value of -1.

char * virDomainGetXMLDesc (virDomainPtr domain, unsigned int flags)

<domain>
  <devices>
    <graphics type='vnc' port='5900' autoport='yes'/>
  </devices>
</domain>

References

http://libvirt.org/html/libvirt-libvirt.html#virDomainGetXMLDesc

score 4 · Answer 3 · edited Aug 09 '16 at 20:28

4

Here's how you do it in python, in case anyone needs this.

Save as vncport.py

from xml.etree import ElementTree as ET

import sys
import libvirt

conn = libvirt.open()

domain = conn.lookupByName(sys.argv[1])

#get the XML description of the VM
vmXml = domain.XMLDesc(0)
root = ET.fromstring(vmXml)

#get the VNC port
graphics = root.find('./devices/graphics')
port = graphics.get('port')

print port

Run Command

python vncport.py <domain name>

edited Aug 09 '16 at 20:28

Mike Glenn

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answered Dec 09 '15 at 14:27

Pandrei

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It's worth mentioning for clarity's sake because I wasn't and found this via trial-and-error: This value, since it's coming from the *live* XML info, will properly handle dynamic ports. So if the VM is 3rd VNC VM to start up, this XML definition will show `5902` as you would expect even if the base configuration is `port=5000 autoport=yes`. – Joshua Boniface Dec 20 '20 at 21:03

score 0 · Answer 4 · edited May 26 '15 at 12:13

0

Here is one for the PHP version, if anyone needs this:

    $res = libvirt_domain_lookup_by_name($conn, $domname);
    $xmlString = libvirt_domain_get_xml_desc($res, '');

    $xml = simplexml_load_string($xmlString);
    $json = json_encode($xml);
    $data = json_decode($json,TRUE);

    $port = intval($data["devices"]["graphics"]["@attributes"]["port"]);

edited May 26 '15 at 12:13

slm

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answered Mar 30 '15 at 17:58

Benjamin Piette

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How to get VNC port number using libvirt?

4 Answers4

References