tini
Tini is a lightweight init system designed for containers. It serves as a simple process supervisor that spawns a single child process and waits for it to exit while performing two key functions: reaping zombie processes and forwarding signals. By integrating Tini into a container, applications are protected from zombie process accumulation that can exhaust PID resources over time. It also ensures default signal handlers like SIGTERM work correctly for software that has not explicitly installed signal handlers, all without requiring changes to existing container images. Tini is included in Docker 1.13 and later through the --init flag, and pre-built binaries and packages are available for Alpine Linux, NixOS, and various distributions. It can be used as a Docker entrypoint, with signed binaries and checksums available for verification. Tini is well-suited for any containerized application that needs proper signal handling and zombie process cleanup without adding significant overhead.