A Docker entrypoint script that renders templates and runs scripts before starting the main application.

An example Dockerfile:

FROM nginx

COPY nginx.conf /templates/etc/nginx/nginx.conf

ADD https://github.com/jcassee/parameterized-entrypoint/releases/download/0.9.0/entrypoint_linux_amd64 /usr/local/bin/entrypoint
RUN chmod +x /usr/local/bin/entrypoint

ENTRYPOINT ["entrypoint", "--"]

RUN ["nginx", "-g", "daemon off;"]

When you run the container, all environment variables will be available in the nginx.conf template:

docker run -e domain=www.example.com example/nginx

If using environment variables is inconvenient, for example because the values are structured, you can set them in /variables.yml:

echo 'domain: www.example.com' > variables.yml
docker run -v $PWD/variables.yml:/variables.yml example/nginx

Paths can be customized using entrypoint command line options. See entrypoint -h for more details.

If you are debugging a container it is sometimes useful to disable the entrypoint functionality. Set the SKIP_ENTRYPOINT environment variable to a non-empty value to only run the command.

pip install -r requirements.txt
python setup.py build

The application is available at dist/entrypoint.

It is also possible to build the Alpine Linux binary using Docker:

python setup.py build_alpine

The Alpine binary will be saved to dist/entrypoint-alpine. In order to use it, though, you need to add the following directive to your Dockerfile:

RUN ln -sfn /lib /lib64 && \
    ln -sfn /lib/ld-musl-x86_64.so.1 /lib/ld-linux-x86-64.so.2

(See this discussion on GitHub.)