Metadata via the DHCP namespace

This is a follow-on from the previous post that described how metadata requests go from instances to the Nova metadata service via a namespace proxy in a Quantum router namespace. This post shows how requests can go via a namespace proxy in a DHCP namespace instead.

Metadata via the Quantum router

Grizzy adds support for the Nova metadata service to work with overlapping IP address spaces from Quantum. Now Quantum proxies metadata requests to Nova adding HTTP headers which Nova uses to identify the source instance. Quantum actually uses two proxies to do this: a namespace proxy and a metadata agent. This post shows how a metadata request gets from an instance to the Nova metadata service via a namespace proxy running in a Quantum router. It is also possible to run the namespace proxy in a DHCP namespace, but that is not covered here.

Path MTU discovery and GRE

When using the Open vSwitch Quantum plugin with GRE there can be problems connecting to some sites while other sites work fine. E.g. 'git clone' hangs or 'apt-get update' takes over an hour. This is because the GRE tunnel can reduce the path MTU to a value less than the common 1500 bytes, and some sites do not engage in standard techniques for path MTU discovery.

Dnsmasq logging and options for the Quantum DHCP agent

Dnsmasq logs to syslog by default when the Quantum DHCP agent is configured to use it as the DHCP driver. This fills the syslog on the network node very quickly with dnsmasq messages - a request and reply line once per minute per instance when the lease time is the default 120 seconds. This post shows how to make dnsmasq log to a different file, give extra log detail and provide additional DHCP options for the clients.