It is very much possible to dynamically change the time in a Docker container, without effecting the host OS.
The solution is to fake it. This lib intercepts all system call programs use to retrieve the current time and date.
The implementation is easy. Add functionality to your Dockerfile as appropriate:
WORKDIR /
RUN git clone https://github.com/wolfcw/libfaketime.git
WORKDIR /libfaketime/src
RUN make install
Remember to set the environment variables LD_PRELOAD
before you run the application you want the faked time applied to.
Example:
CMD ["/bin/sh", "-c", "LD_PRELOAD=/usr/local/lib/faketime/libfaketime.so.1 FAKETIME_NO_CACHE=1 python /srv/intercept/manage.py runserver 0.0.0.0:3000]
You can now dynamically change the servers time:
Example:
def set_time(request):
import os
import datetime
print(datetime.datetime.today())
os.environ["FAKETIME"] = "2020-01-01" # string must be "YYYY-MM-DD hh:mm:ss" or "+15d"
print(datetime.today())