Alpine libfaketime

A simple image containing libfaketime built with Alpine build tools for use with multistage builds.

The intent of this project is to be used in Docker multistage builds to add faketime support to your containers for local testing.

Only the multithreaded version is used and stored as /faketime.so.

Usage

The Dockerfile used to build shows how the image is built and tested. However to use it in a multisage build the Dockerfile using the COPY --from=trajano/alpine-libfaketime and setting the proper environment variables.

With simple command line apps

FROM alpine
COPY --from=trajano/alpine-libfaketime  /faketime.so /lib/faketime.so
ENV LD_PRELOAD=/lib/faketime.so

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

docker build -f fakedemo.Dockerfile . -t fakedemo
docker run --rm -e FAKETIME=+15d fakedemo date

With Java

For example purposes groovy was used as it is a JVM language that allows us to pass a simple script to run from the command line. The key thing to note is that the DONT_FAKE_MONOTONIC=1 environment variable should be set as documented in libfaketime.

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();"