Here is our simple tip for your healthy server’s date and time:
Immediately synchronize the clock of your computer when using the openntpd (a lightweight version of ntpd with client-only mode).
Use the “-s” (lower “s” letter) to instruct the daemon ntpd to synchronize the clock immediately after it discovers a healthy time server!
-s Try to set the time immediately at startup, as opposed to slowly adjusting the clock. ntpd will stay in the foreground for up to 15 seconds waiting
for one of the configured NTP servers to reply.
Find the start-up configuration file in your “/etc” (for your Linux distribution, its name is probably ntpd, for Gentoo it is “/etc/conf.d/ntpd”, the thing is to find the start-up confiuration script, not the ntpd.conf, which is the ntpd configuration file for the daemon) and include “-s” in the NTPD_OPTS:
# /etc/conf.d/ntpd: config file for openntpd's ntpd
Restart the service.
If you use it in a virtualized environment like containers (docker, lxc, lxd and so on) and qemu, virtualbox, vmware and so on and you often suspend the machine to synchronize the clock when you resume it you must manually restart the openntpd service!!! Or you are going to wait for slowly adjusting the time as usual.
There is a utility to check what’s going on with the openntpd – ntpctl. It has only three read-only commands:
usage: ntpctl -s all | peers | Sensors | status
Keep on reading!
Invalid time could cause your server (or probably your virtual server or docker instance) to be unable to use Ubuntu’s packaging system apt. It is a typical thing if your virtual or docker instance does not use automatic time synchronization.
It is really important even small installation and virtualized environments to have automatic time synchronization or the service they provide could become error prone with time!
The “apt” just reports the repositories are not valid yet:
myuser@my-server-pc:~$ sudo su
root@my-server-pc:/home/myuser# apt update
Hit:1 http://archive.ubuntu.com/ubuntu bionic InRelease
Get:2 http://archive.ubuntu.com/ubuntu bionic-updates InRelease [88.7 kB]
Get:3 http://archive.ubuntu.com/ubuntu bionic-backports InRelease [74.6 kB]
Get:4 http://archive.ubuntu.com/ubuntu bionic-security InRelease [88.7 kB]
Reading package lists... Done
E: Release file for http://archive.ubuntu.com/ubuntu/dists/bionic-updates/InRelease is not valid yet (invalid for another 151d 18h 5min 59s). Updates for this repository will not be applied.
E: Release file for http://archive.ubuntu.com/ubuntu/dists/bionic-backports/InRelease is not valid yet (invalid for another 151d 17h 16min 26s). Updates for this repository will not be applied.
E: Release file for http://archive.ubuntu.com/ubuntu/dists/bionic-security/InRelease is not valid yet (invalid for another 151d 17h 15min 3s). Updates for this repository will not be applied.
Thu Jan 17 15:11:56 UTC 2019
The clock shows 17 January 2019, but now is 18 June 2019! This is a Ubuntu virtual server with the minimal installation.
The solution is to synchronize your clock manually or use a service (the better way)!
Keep on reading!