support NTPSERVERARGS in /etc/sysconfig/network

This bug was originally filed in Launchpad as [LP: #1819966](https://bugs.launchpad.net/cloud-init/+bug/1819966)

Launchpad details

affected_projects = []

assignee = None

assignee_name = None

date_closed = None

date_created = 2019-03-13T20:13:59.013898+00:00

date_fix_committed = None

date_fix_released = None

id = 1819966

importance = medium

is_complete = False

lp_url = https://bugs.launchpad.net/cloud-init/+bug/1819966

milestone = None

owner = bgermain1689

owner_name = Brendan Germain

private = False

status = confirmed

submitter = bgermain1689

submitter_name = Brendan Germain

tags = []

duplicates = []

_Launchpad user **Brendan Germain(bgermain1689)** wrote on 2019-03-13T20:13:59.013898+00:00_

I'm not sure what's changed but in previous versions of cloud-init, it was not owning/writing contents to /etc/sysconfig/network.

I DHCP my ntp endpoints and provide ntp options via NTPSERVERARGS. Example:

echo 'NTPSERVERARGS="minpoll 3 maxpoll 4"' >> /etc/sysconfig/network

$ grep server /etc/ntp.conf
server 10.155.55.1 minpoll 3 maxpoll 4 # added by /sbin/dhclient-script

On boot now /etc/sysconfig/network only has:
$ cat /etc/sysconfig/network
# Created by cloud-init on instance boot automatically, do not edit.
#
NETWORKING=yes

So how can i prevent cloud-init from modifying it, or have it write the additional option (NTPSERVERARGS) that i need?