NTP, the Network Time Protocol, is used to keep computer clocks accurate
by synchronizing them over the Internet or a local network, or by
following an accurate hardware receiver that interprets GPS, DCF-77,
NIST or similar time signals.
This charm can be deployed alongside principle charms to enable NTP
management across deployed services.
NTP provides network based time services to ensure synchronization of time
The ntp charm is a subordinate charm that is design for use with other
principle charms. It can be used in two ways:
In this mode the ntp charm is used to configure NTP in other service units to
talk directly to a set of NTP time sources:
juju deploy ntp
juju add-relation ntp myservice
By default this is the standard set of NTP pool servers that are configured in
the ntp Ubuntu package.
However, if you have a handy atomic clock on your network which you would prefer
to trust then you can use that instead:
juju set ntp source=myatomiclock.local.net
You can also specify multiple sources and peers:
juju set ntp source="mac1.local.net mac2.local.net mac3.local.net"
juju set ntp peers="mac1.local.net mac2.local.net mac3.local.net"
Sources and peers should be space separated.
When you need a set of services to keep close time to each other, it may
be useful to have them automatically peer with each other. This means
any set of services that use the same ntp subordinate will peer together.
juju set ntp auto_peers=true
This will add all the hosts as peers to each other.
In the event that you don't wish every server on your network to talk directly to
your trusted time sources, you can use this charm in-conjunction with the ntpmaster
juju deploy ntp
juju deploy ntpmaster
juju add-relation ntp ntpmaster
This allows you to gate NTP services to a single set of servers within your control.
This might have application in more secure network environments where general
outbound network access to the Internet is not avaliable or desirable and you don't
have a good internal time source such as an atomic clock.
You can of course have more that one ntpmaster:
juju add-unit ntpmaster
All services that the ntp charm is subordinate to will be configured to sync with
all avaliable masters.
The ntpmaster charm supports the same "source" configuration that the ntp charm does.