[libvirt] problem trying to use net-update

Well, you could indirectly trigger it by adding (and then removing) a dhcp <range> element with virsh net-update. > > > >Is there some way (some command) that will cause dnsmasq to be > >restarted (possibly with new parameters as it re-does its > >configuration). If this was done, then little, except some cached > >names, would be lost). If there is not, maybe there should be. > >However, there are likely limits such as not changing the gateway > >addresses on the interface. I recently made a patch to check for a running dnsmasq anytime libvirt is restarted. If it's not running, it will be restarted. If it is running, a SIGHUP will be sent. Aside from that, the (newly created) accepted way to change a network's config while the network is up is to use the virNetworkUpdate API (available via virsh net-update). It permits you to add/delete/modify certain parts of the network config and have those changes take effect immediately if desired. the bridge_driver backend of virNetworkUpdate decides when it is necessary to either SIGHUP or restart dnsmasq according to what parts of the network definition have changed. A "live" change of the entire network definition (i.e. with virNetworkDefine() isn't supported, and won't be - anything that you want to be able to change while the network is up should be added to the "sections" modifiable by virNetworkUpdate. This will permit us to easily figure out what re-initialization is needed for a particular change without needing to just redo everything (for example, if a dhcp static host is added, we just need to SIGHUP dnsmasq, but if a dynamic range is added/deleted, we need to restart dnsmasq. If an IP address is added/removed from the bridge, we should be able to write code to simply redo the IP addresses on the existing bridge, rather than tear it down and build a new bridge (although that one isn't implemented yet).