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Re: [libvirt] [PATCH 1/2] v3: put dnsmasq parameters into a file instead of the command line



On 10/24/2012 07:46 AM, Gene Czarcinski wrote:
On 10/23/2012 04:10 PM, Laine Stump wrote:
>Can you provide a bit more info as to what you would like to change
>without restarting dnsmasq.
Right now, the ranges of IP addresses, the IP addresses to listen on,
the domain. There may be other things in the future as
virNetworkUpdate() gets fleshed out.
http://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2012q4/006440.html
The most difficult problem is that dnsmasq throws away root permissions after start-up, so re-reading the configuration is impossible if acting on the new configuration involves anything that needs root (for instance, binding sockets to ports <1024 or opening the lease file.)

The philosophy is that things that would be really useful to change, without restarting dnsmasq, and certainly don't need root, are re-read on SIGHUP. That's dhcp-host information and dhcp-option information in special configuration files, /etc/hosts and /etc/ethers, and possibly /etc/resolv.conf, if it's not being polled anyway.

For anything else, restarting dnsmasq is a pain-free operation anyway: there's very little state and nothing important is lost over a reboot.

One other thought occurs to me.

As far as I know, the only way to get dnsmasq restarted is to do a net-destroy and then a net-start. While you can do this while a virtual guest is on that network, the virtual guest has to be rebooted for it to work again.

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.

Gene

Gene


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