Frequently asked questions about VNC access to virtual machines

Q: What is the difference between nova-xvpvncproxy and nova-novncproxy?

A: nova-xvpvncproxy, which ships with OpenStack Compute, is a proxy that supports a simple Java client. nova-novncproxy uses noVNC to provide VNC support through a web browser.

Q: I want VNC support in the OpenStack dashboard. What services do I need?

A: You need nova-novncproxy, nova-consoleauth, and correctly configured compute hosts.

Q: When I use nova get-vnc-console or click on the VNC tab of the OpenStack dashboard, it hangs. Why?

A: Make sure you are running nova-consoleauth (in addition to nova-novncproxy). The proxies rely on nova-consoleauth to validate tokens, and waits for a reply from them until a timeout is reached.

Q: My VNC proxy worked fine during my all-in-one test, but now it doesn't work on multi host. Why?

A: The default options work for an all-in-one install, but changes must be made on your compute hosts once you start to build a cluster. As an example, suppose you have two servers:

PROXYSERVER (public_ip=172.24.1.1, management_ip=192.168.1.1)
COMPUTESERVER (management_ip=192.168.1.2)

Your nova-compute configuration file must set the following values:

# These flags help construct a connection data structure
vncserver_proxyclient_address=192.168.1.2
novncproxy_base_url=http://172.24.1.1:6080/vnc_auto.html
xvpvncproxy_base_url=http://172.24.1.1:6081/console

# This is the address where the underlying vncserver (not the proxy)
# will listen for connections.
vncserver_listen=192.168.1.2

	Note
	novncproxy_base_url and xvpvncproxy_base_url use a public IP; this is the URL that is ultimately returned to clients, which generally do not have access to your private network. Your PROXYSERVER must be able to reach vncserver_proxyclient_address, because that is the address over which the VNC connection is proxied.

Q: My noVNC does not work with recent versions of web browsers. Why?

A: Make sure you have installed python-numpy, which is required to support a newer version of the WebSocket protocol (HyBi-07+).

Q: How do I adjust the dimensions of the VNC window image in the OpenStack dashboard?

A: These values are hard-coded in a Django HTML template. To alter them, edit the _detail_vnc.html template file. The location of this file varies based on Linux distribution. On Ubuntu 12.04, the file is at /usr/share/pyshared/horizon/dashboards/nova/instances/templates/instances/_detail_vnc.html.

Modify the width and height options, as follows:

<iframe src="{{ vnc_url }}" width="720" height="430"></iframe>