Do signal handling and orphan reaping for Unix PID1 init processes.
This provides a Haskell library, and an executable based on that library, for initializing signal handlers, spawning and child process, and reaping orphan processes. These are the responsibilities that must be fulfilled by the initial process in a Unix system, and in particular comes up when running Docker containers.
This library/executable will automatically detect if it is run as some process
besides PID1 and, if so, use a straightforward
exec system call instead.
NOTE This package is decidedly not portable, and will not work on Windows. If you have a use case where you think it makes sense to run on Windows, I’d be interested in hearing about it.
For a discussion on why this is useful, see this repo.
The recommended use case for this executable is to embed it in a Docker image.
Assuming you’ve placed it at
/sbin/pid1, the two commonly recommended usages
Override the entrypoint, either via
ENTRYPOINTin your Dockerfile or
--entrypointon the command line.
docker run --rm --entrypoint /sbin/pid1 fpco/pid1 ps
/sbin/pid1to the beginning of your command.
docker run --rm --entrypoint /usr/bin/env fpco/pid1 /sbin/pid1 ps
- Turn off all RTS options
- Initial release