VyOS is currently incompatible with the use of upstreams that provide leap smear, such as time.aws.com and time.google.com. This is because /run/chrony/chrony.conf contains:
# Determine when will the next leap second occur and what is the current offset leapsectz right/UTC
It could also be good to support having the router handle leap smearing, using normal upstreams.
I propose introducing the config node leapsec under service ntp with the following possible values:
- Missing (default) -> leapsectz right/UTC.
- ignore -> leapsecmode ignore
- smear -> leapsecmode slew, maxslewrate 1000, and smoothtime 400 0.001 leaponly as recommended by https://chrony-project.org/doc/3.5/chrony.conf.html