New rules cause dnsmasq to be restarted instead of reloaded

[rohityadavcloud]

When adding/configuring new dhcp/dns rules, the dnsmasq process is restarted:
https://github.com/apache/cloudstack/blob/master/systemvm/debian/opt/cloud/bin/cs/CsDhcp.py#L71

Explore if it's possible to simply reload the dnsmasq process than restart it.

(If dnsmasq restarts at the same time monitoring service check kicks in, it might show to recover the dnsmasq again)

ISSUE TYPE

• Improvement Request

COMPONENT NAME

VR

[onitake]

Restarting should not be necessary for reloading DNS and DHCP records, according to the man page: http://www.thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html#lbAG
Quote:

When it receives a SIGHUP, dnsmasq clears its cache and then re-loads /etc/hosts and /etc/ethers and any file given by --dhcp-hostsfile, --dhcp-hostsdir, --dhcp-optsfile, --dhcp-optsdir, --addn-hosts or --hostsdir. The dhcp lease change script is called for all existing DHCP leases. If --no-poll is set SIGHUP also re-reads /etc/resolv.conf. SIGHUP does NOT re-read the configuration file.

The systemd unit in Debian buster sends a SIGHUP on reload, so it should suffice:

ExecReload=/bin/kill -HUP $MAINPID

[andrijapanicsb]

it WAS necessary some days (years?) ago since there was no way to reload the dnsmasq (or it was buggy) - but today - you are right.

[rohityadavcloud]

This will require large changes, moved to 4.15