Docker Container time & timezone (will not reflect changes)

Question

Where do Docker containers get their time information? I've created some containers from the basic ubuntu:trusty image, and when I run it and request 'date', I get UTC time.

For awhile I got around this by doing the following in my Dockerfile:

RUN sudo echo "America/Los_Angeles" > /etc/timezone

However, for some reason that stopped working. Searching online I saw the below suggested:

docker run -v /etc/timezone:/etc/timezone [image-name]

Both these methods correctly set the timezone though!

$ cat /etc/timezone
America/Los_Angeles
$ date
Tue Apr 14 23:46:51 UTC 2015

Anyone know what gives?

Answer 1

The secret here is that dpkg-reconfigure tzdata simply creates /etc/localtime as a copy, hardlink or symlink (a symlink is preferred) to a file in /usr/share/zoneinfo. So it is possible to do this entirely from your Dockerfile. Consider:

ENV TZ=America/Los_Angeles
RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ > /etc/timezone

And as a bonus, TZ will be set correctly in the container as well.

This is also distribution-agnostic, so it works with pretty much any Linux.

Note: if you are using an alpine based image you have to install the tzdata first. (see this issue here)

Looks like this:

RUN apk add --no-cache tzdata
ENV TZ America/Los_Angeles

Answer 2

Usually it is sufficient to set an environment variable in the docker container, like so:

docker run -e TZ=Europe/Amsterdam debian:jessie date

Of course this would work also with docker-compose.

Answer 3

You can add your local files (/etc/timezone and /etc/localtime) as volume in your docker-container.

Update your docker-compose.yml with the following lines.

volumes:
    - "/etc/timezone:/etc/timezone:ro"
    - "/etc/localtime:/etc/localtime:ro"

Now the container time is the same as on your host

Answer 4

Mounting /etc/localtime in the image, so it is in sync with host -v is the most popular one.

But see issue 12084:

it is not correct because it does not work when the software requires instead the file /etc/timezone to be set.
That way you are using leaves it as the default value etc/UTC.

I have determined that actually there is no foolproof elegant way to set the time zone inside of a docker container.
So have finally settled on this solution:

App dockerfile:

# Relocate the timezone file
RUN mkdir -p /config/etc && mv /etc/timezone /config/etc/ && ln -s /config/etc/timezone /etc/

App entrypoint script:

# Set timezone as specified in /config/etc/timezone
dpkg-reconfigure -f noninteractive tzdata

Data volume /config dockerfile, localized to a specific country or region:

# Set the time zone
RUN echo "Europe/London" > /config/etc/timezone

... it is not elegant because involving 3 separate files, and re-creating /etc/localtime on every runtime container start. Which is rather wasteful.

However it does work properly, and successfully achieve separation between the base app image, and each per-country localized configuration.
In 3 lines of code.

Answer 5

In ubuntu 16.04 image there is bug. Solution was

    ENV TZ 'Europe/Tallinn'
    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

Answer 6

if you are using docker image based on ubuntu :

# Change the docker default timezone from UTC to SGT
echo "Asia/Singapore" > /etc/timezone
dpkg-reconfigure tzdata
date

Answer 7

Adding my two cents here, because I've tried several of these but none worked on alpine-based images.

However, this did the trick:

ENV TZ=America/Toronto
RUN apk update
RUN apk upgrade
RUN apk add ca-certificates && update-ca-certificates
RUN apk add --update tzdata
RUN rm -rf /var/cache/apk/*

[Source]

Answer 8

In alpine basic Image (example use node:10.16.0-alpine):

Dockerfile

FROM node:10.16.0-alpine

ENV TZ=America/Los_Angeles

RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ > /etc/timezone

WORKDIR /app

COPY package.json package-lock.json ./

RUN npm i --production

COPY . .

CMD node index.js

Answer 9

Using a Fedora container (likely to work with ubuntu also):

The simplest solution I found was to use the following in docker-compose.yml

environment: 
  TZ: "${TZ:-America/Los_Angeles}"

Then in your .env file (which docker-compose automatically reads)

TZ=America/Los_Angeles

This allows you to put docker-compose.yml under version control and use a customized .env file which can be ignored by git.

You get a default value for the container and you get customization, best of both worlds.

For Fedora no other changes were necessary, it just works!

Answer 10

Thanks to VonC for the information and link to the issue. This seems like such a convoluted mess, so I did some testing on my own idea of how to solve this and it seems to work great.

>docker run -it ubuntu:trusty /bin/bash
#dpkg-reconfigure tzdata

(follow prompts to select my timezone)

>docker commit [container-id] chocko/ubuntu:local

Then I updated my Dockerfiles to reflect this:

FROM chocko/ubuntu:local

There must be something wrong with this because it seems too easy to be overlooked... Or is this acceptable?

Answer 11

A more generic way to set the timezone in docker run arguments:

-e TZ=`ls -la /etc/localtime | cut -d/ -f8-9`

Or for reuse:

function GET_TZ () {
    ls -la /etc/localtime | cut -d/ -f8-9
}

...
-e TZ=`GET_TZ`

Answer 12

The simplest way is to add -e option or ENV directive to set TZ environment variable, because debian, ubuntu, etc. already included tzdata.

Someone recommends to mount the timezone from the host:

$ docker run -it --rm \
-v /etc/localtime:/etc/localtime \
-v /etc/timezone:/etc/timezone \
debian:bullseye date
Mon Jul  3 19:41:30 CST 2023

This may work, but it is dangerous. Because /etc/localtime is actually a symbol link (in some newer distributions), and Docker by default follow the symbol link. As a result, the timezone data (instead of the symbol link it self) is overridden silently.

$ docker run -it --rm debian:bullseye \
sh -c 'ls -l /etc/localtime && tail -n1 /etc/localtime'
lrwxrwxrwx 1 root root 27 Mar 20 00:00 /etc/localtime -> /usr/share/zoneinfo/Etc/UTC
UTC0
$ docker run -it --rm -v /etc/localtime:/etc/localtime debian:bullseye \
sh -c 'ls -l /etc/localtime && tail -n1 /etc/localtime'
lrwxrwxrwx 1 root root 27 Mar 20 08:00 /etc/localtime -> /usr/share/zoneinfo/Etc/UTC
CST-8

That is why this does not work:

$ docker run -it --rm \
-v /usr/share/zoneinfo:/usr/share/zoneinfo \
-v /etc/localtime:/etc/localtime \
-v /etc/timezone:/etc/timezone \
debian:bullseye date
Mon Jul  3 11:41:59 UTC 2023