Depending on specific functional requirements of a concrete
production environment, the Red Hat Enterprise Linux CoreOS 4 system can be
configured to utilize the services of the chronyd NTP daemon (the
default), or services of the ntpd NTP daemon. Refer to
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/system_administrators_guide/ch-configuring_ntp_using_the_chrony_suite
for more detailed comparison of the features of both of the choices, and for
further guidance how to choose between the two NTP daemons.
To specify a remote NTP server for time synchronization, perform the following:
- if the system is configured to use the
chronyd as the NTP daemon (the
default), edit the file /etc/chrony.conf as follows,
- if the system is configured to use the
ntpd as the NTP daemon,
edit the file /etc/ntp.conf as documented below.
Add or correct the following lines, substituting the IP or hostname of a remote
NTP server for ntpserver:
server ntpserver
This instructs the NTP software to contact that remote server to obtain time
data.
Note that if the remediation shipping with this content is being used, the
MachineConfig shipped does not include reference NTP servers to point
to. It is up to the admin to set these which will vary depending on the
cluster's requirements.
The aforementioned remediation does include the directory /etc/chrony.d
which would allow the creation of configuration files to set these servers.
If we'd like to set a configuration like the following:
pool 2.rhel.pool.ntp.org iburst
server 0.rhel.pool.ntp.org minpoll 4 maxpoll 10
server 1.rhel.pool.ntp.org minpoll 4 maxpoll 10
server 2.rhel.pool.ntp.org minpoll 4 maxpoll 10
server 3.rhel.pool.ntp.org minpoll 4 maxpoll 10
This could be done with to the following manifest:
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
metadata:
labels:
machineconfiguration.openshift.io/role: master
name: 75-master-chrony-servers
spec:
config:
ignition:
version: 3.1.0
storage:
files:
- contents:
source: data:,pool%202.rhel.pool.ntp.org%20iburst%0A%0Aserver%200.rhel.pool.ntp.org%20minpoll%204%20maxpoll%2010%0Aserver%201.rhel.pool.ntp.org%20minpoll%204%20maxpoll%2010%0Aserver%202.rhel.pool.ntp.org%20minpoll%204%20maxpoll%2010%0Aserver%203.rhel.pool.ntp.org%20minpoll%204%20maxpoll%2010
mode: 0600
path: /etc/chrony.d/10-rhel-pool-and-servers.conf
overwrite: true
Note that this needs to be done for each MachineConfigPool