Docker Init Process: The Zombie Reaper

Running a process as PID 1 in a container has side effects. The most common is the “Zombie Process” problem.

The Problem

In Linux, only PID 1 can reap orphaned child processes. If your app (e.g., Node.js or Java) runs as PID 1 but doesn’t handle `SIGCHLD` signals, zombies accumulate, exhausting the process table.

The Solution: Tini

Use `tini` as your entrypoint. It acts as a lightweight init system.

# Add tini
ENV TINI_VERSION v0.19.0
ADD https://github.com/krallin/tini/releases/download/${TINI_VERSION}/tini /tini
RUN chmod +x /tini
ENTRYPOINT ["/tini", "--"]

# Run your program
CMD ["node", "app.js"]

Or simply use `–init` when running `docker run`.