trajano/alpine-libfaketime repository overview

⁠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();"