Will docker container auto sync time with the host machine?
Giving I already changed the timezone of docker container correctly. Do I need to install a NTP server inside the docker container to periodically sync the time or the container will sync the time from its host machine?
Answer
If you are on OSX running boot2docker, see this issue: https://github.com/boot2docker/boot2docker/issues/290
Time synch becomes an issue because the boot2docker host has its time drift while your OS is asleep. Time synch with your docker container cannot be resolved by running your container with -v /etc/localtime:/etc/localtime:ro
Instead, for now, you have to periodically run this on OSX:
/usr/local/bin/boot2docker ssh sudo ntpclient -s -h pool.ntp.org
Update for users of Kitematic
If you are running Kitematic, which is now the suggested mechanism for getting up and running on Docker in OSX, you will have to periodically run this command:
docker-machine ssh default 'sudo ntpclient -s -h pool.ntp.org'
Or, for older versions of docker
docker-machine ssh dev 'sudo ntpclient -s -h pool.ntp.org'
Update for users of new native Docker for OSX
The new Docker Beta does away with VirtualBox and Docker Machine. The latest builds of docker (currently, 1.12.1-beta25 (build: 11807)) seem to have the ability to detect when there has been a time discontinuity and adjust accordingly. Thus, this should no longer be an issue...hooray!!