Is it possible change date in docker container?

Question

I have a container with a running program inside tomcat. I need to change date only in this container and test my program behaviour. I have time sensitive logic, and sometim

Answer 1

I created a Docker image containing libfaketime for use with Alpine but the process can be done in other distributions.

Here's an example of using it Java using Groovy as an example. But Tomcat can be used as well.

FROM groovy:alpine
COPY --from=trajano/alpine-libfaketime  /faketime.so /lib/faketime.so
ENV LD_PRELOAD=/lib/faketime.so \
    DONT_FAKE_MONOTONIC=1

Then build and pass the FAKETIME environment variable when doing a docker run for example

docker build -f fakedemo-java.Dockerfile . -t fakedemo
docker run --rm -e FAKETIME=+15d fakedemo groovy -e "print new Date();"

Source is in https://github.com/trajano/alpine-libfaketime and the docker image is in https://hub.docker.com/r/trajano/alpine-libfaketime

I also created a variant of it based on Ubuntu https://github.com/trajano/ubuntu-faketime