AWS EC2 Ubuntu 14.04 instance clock running 12 minutes ahead

Question

We are using Ubuntu 14.04 (LTS) on Amazon EC2 m4.xlarge instances. It seems the instance clock is running 12 minutes ahead of the current time.

I am using python shell to check time by running this command

import datetime; datetime.datetime.utcnow()

I was wondering if there is any solution to this issue that does not involve an instance restart.

Thanks

Answer 1

You must edit the chrony configuration file to add a server entry for the Amazon Time Sync Service.

To configure your instance to use the Amazon Time Sync Service

1. Connect to your instance and use apt to install the chrony package.

ubuntu:~$ sudo apt install chrony

Note

If necessary, update your instance first by running sudo apt update.

2. Open the /etc/chrony/chrony.conf file using a text editor (such as vim or nano). Add the following line before any other server or pool statements that are already present in the file, and save your changes:

server 169.254.169.123 prefer iburst

3. Restart the chrony service.

ubuntu:~$ sudo /etc/init.d/chrony restart

[ ok ] Restarting chrony (via systemctl): chrony.service.

4. [ ok ] Restarting chrony (via systemctl): chrony.service.

ubuntu:~$ chronyc sources -v

 210 Number of sources = 7

  .-- Source mode  '^' = server, '=' = peer, '#' = local clock.
 / .- Source state '*' = current synced, '+' = combined , '-' = not combined,
| /   '?' = unreachable, 'x' = time may be in error, '~' = time too variable.
||                                                 .- xxxx [ yyyy ] +/- zzzz
||      Reachability register (octal) -.           |  xxxx = adjusted offset,
||      Log2(Polling interval) --.      |          |  yyyy = measured offset,
||                                \     |          |  zzzz = estimated error.
||                                 |    |           \
MS Name/IP address         Stratum Poll Reach LastRx Last sample
===============================================================================
^* 169.254.169.123               3   6    17    12    +15us[  +57us] +/-  320us
^- tbag.heanet.ie                1   6    17    13  -3488us[-3446us] +/- 1779us
^- ec2-12-34-231-12.eu-west-     2   6    17    13   +893us[ +935us] +/- 7710us
^? 2a05:d018:c43:e312:ce77:6     0   6     0   10y     +0ns[   +0ns] +/-    0ns
^? 2a05:d018:d34:9000:d8c6:5     0   6     0   10y     +0ns[   +0ns] +/-    0ns
^? tshirt.heanet.ie              0   6     0   10y     +0ns[   +0ns] +/-    0ns
^? bray.walcz.net                0   6     0   10y     +0ns[   +0ns] +/-    0ns

In the output that's returned, ^* indicates the preferred time source.

5. Verify the time synchronization metrics that are reported by chrony.

ubuntu:~$ chronyc tracking

Reference ID    : 169.254.169.123 (169.254.169.123)
Stratum         : 4
Ref time (UTC)  : Wed Nov 29 07:41:57 2017
System time     : 0.000000011 seconds slow of NTP time
Last offset     : +0.000041659 seconds
RMS offset      : 0.000041659 seconds
Frequency       : 10.141 ppm slow
Residual freq   : +7.557 ppm
Skew            : 2.329 ppm
Root delay      : 0.000544 seconds
Root dispersion : 0.000631 seconds
Update interval : 2.0 seconds
Leap status     : Normal