Shentrypoint is a script that provides an easy way to debug your Docker applications without getting in your way. Shentrypoint does run as PID 1, but it doesn't aim to be a full init process.
- When your container starts, your application should start
- When your application dies, your container should die
- When you send control signals to your container, your application process should receive them
- When you send SIGINT (CTRL+C) to your container, you should get a shell prompt (not a stopped container) as if you'd been running your application process in the foreground from a shell all along
We put together a lot of automation around running containers in terms
of configuration for inputs, network, volumes, etc, not to mention
connecting these containers to other systems in a deployment. Sometimes,
the easiest way to get a debugging environment is to take over an
existing container. Shentrypoint makes it possible to docker attach to
an existing container and you can pretend you had launched the
application as a foreground process all along. You can hit CTRL+C,
modify your container's filesystem, run arbitrary commands, restart your
application and debug it interactively.
- Create a Procfile where the keys are the command words you want to run later
- Add shentrypoint to your docker image
- Add
ENTRYPOINT /path/to/shentrypointto your Dockerfile
Use the command words defined in your Procfile to run your containers