Change time zone for docker and Dockerfile

Question

I have an AWS EC2 instance that I have scheduled to open at 11:50 PM MST and close at 11:59 PM PST. I have set the timezone of the instance to MST so that I can run a cron job that executes a .sh file at 11:55 PM MST. The cron job is pretty simple: 55 23 * * * sudo bash docker run --mount type=bind,source="/home/ec2-user/environment/Project",target="/Project" myubuntu. The docker will mount to a local folder "Project" that contains a .cpp file that web scrapes data from Steam's user information page. The code within the .cpp file is very reliant on the current time/date, hence why I have gone through so much work to get everything running in MST so that everything is standard throughout. However, even with everything running on MST, when the docker container is running it is not in MST despite the dockerfile stating to run with ENV TZ="America/Salt Lake City", I have since changed it from Salt Lake City to Phoenix just to try it out but it still doesn't run the docker in MST. For example, when I run the docker at 9:22 PM MST Nov 24th, the date within the docker is 04:22 AM UTC Nov 25th. This slight date and time change is greatly affecting the code I am trying to run.

To kind of explain what the code does, Steam has a .json URL that holds about 48-62 hours worth of data in "[unix epoch time, # users logged in]". The goal is automation so I figured if I had the code cut out any data that did not match the date the code was run at, it would not be included in the data collection. So I am collecting 24 hours worth of data at a time by running the code at the very end of the day every single day. The difference in date/time between the MST time that both I and my EC2 instance are running on and the UTC time my docker is running on is causing data collection issues.

I was given the dockerfile by my professor, and it supposedly is set up to run on MST but it is not from what I can tell. I have tried to run my command within my .sh file with the included -v /etc/timezone:/etc/timezone but that does not seem to fix the timezone issue either. The dockerfile I was given is below:

# This image will be based on the ubuntu image.  Build it using the
# command in the comment below.  You may omit the ubuntu pull if you already
# did it.  Before running the build, change into the directory containing
# this Dockerfile.
FROM ubuntu

# Set a default shell.
SHELL ["/bin/bash", "-c"]

# The timezone library stops the docker build and waits for user input to
# select a timezone. This breaks the build. To get around this, 
# set up timezone information prior to installing that library. This
# Docker code does that. Composited from two sources:
# https://rtfm.co.ua/en/docker-configure-tzdata-and-timezone-during-build/
# https://serverfault.com/questions/949991/how-to-install-tzdata-on-a-ubuntu-docker-image
ARG DEBIAN_FRONTEND=noninteractive
ENV TZ="America/Phoenix"

# Install a handful of useful libraries.  Note that this is generally against
# best practices -- containers should be lean, and not include 'things you
# might use'.  In our case, we're using the containers for development, so
# this may be reasonable here.
RUN apt-get -y update && apt-get -y install \
  apt-utils \
  emacs-nox \
  g++

# Copy in the files from the current folder (recursively) For our purposes,
# put them in /cs3505
COPY . /cs3505

RUN apt-get -y install wget

Is there something I, or my professor, has done wrong in the setup of the docker to cause this timezone issue? How can I go about fixing my docker so that every time it runs at 11:55 PM MST it opens up with MST as the timezone?

Edit: I do not know if this makes a difference but running cat /etc/timezone returns "United States/Mountain" and running emacs /etc/timezone shows the same thing.

Answer 1

This is a dockerfile I customized based on Debian, you can refer to it：

FROM debian:stable-slim

ARG ARG_TIMEZONE=Asia/Shanghai
ENV ENV_TIMEZONE                ${ARG_TIMEZONE}

# install base dependence
RUN echo 'debconf debconf/frontend select Noninteractive' | debconf-set-selections \
    && apt-get update && apt-get install -y -q \
        dialog apt-utils \
        locales systemd cron \
        vim wget curl exuberant-ctags tree \
        tzdata ntp ntpstat ntpdate \
    && apt-get clean && apt-get autoremove -y && rm -rf /var/lib/apt/lists/* \
    && localedef -i en_US -c -f UTF-8 -A /usr/share/locale/locale.alias en_US.UTF-8

# sync timezone
RUN echo '$ENV_TIMEZONE' > /etc/timezone \
    && ln -fsn /usr/share/zoneinfo/$ENV_TIMEZONE /etc/localtime \
    && dpkg-reconfigure --frontend noninteractive tzdata