A time synchronization program such as Network Time Protocol (NTP) is a requirement, as OpenStack services depend on consistent and synchronized time between hosts.

For Nova Compute, having synchronized time helps to avoid problems when scheduling VM launches on compute nodes. Other services can experience similar issues when the time is not synchronized.

To install chrony, an NTP implementation, issue the following commands on all nodes in the environment:

 # apt install chrony

On the controller node, add the following line to the /etc/chrony/chrony.conf file to allow other hosts in the environment to synchronize their time against the controller:

allow 10.10.0.0/24 

On the other nodes, comment out any pool lines in the /etc/chrony/chrony.conf file and add the following line to direct them to synchronize their time against the controller:

# pool 2.debian.pool.ntp.org offline iburst
server controller01 iburst 

On each host, restart the chrony service:

# systemctl restart chrony