Docker tzdata / Timezone configuration

One of the biggest issues with ubuntu and debian that people walk into during docker dev-ops deploys, is the re-configuration of the os-timezone. It has happened quite a few times that os-upgrades and minor version updates, this package gets stuck. In debian, you usually want to run all aptitude, dpkg-reconfigure and apt-get into bash-non-interactive mode. This however often fails in build pipelines as it doesn't always run as such.

The following snippet, will (re-)set the timezone from UTC (which is the standard) to 'Europe/Amsterdam'

ENV TZ 'Europe/Amsterdam'
RUN echo $TZ > /etc/timezone && \
  apt-get update && apt-get install -y tzdata && \
  rm /etc/localtime && \
  ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && \
  dpkg-reconfigure -f noninteractive tzdata && \
  apt-get clean

The snippet can also be used in ansible/chef cookbooks etc. In that case remove the ENV and RUN and hardcode it.

The one-liner updates the packages and installs tzdata. It then removes the localtime file which is sometimes modified to read/modify only (hence the rm) followed by a forced hard-copied symlink.

I myself prefer to use UTC over others but since most of my clients are located in the Netherlands, it is one of the most used configurations I have running. To use UTC:

ln -fs /usr/share/zoneinfo/UTC /etc/localtime

That usually does the trick. You could also simply remove both files since the OS defaults to UTC.

As for defining versions, it is "better", to set the version for the OS hard instead of using ubuntu:latest e.g. ubuntu:18.04. The problem with using FROM ubuntu:latest is that it will auto-upgrade the operating system, and when not tested thouroughly might result in unexpected behaviour.

More information about docker-manifest and buildfiles: Docker - Best Practice