An OCI container runtime monitor.
Conmon is a monitoring program and communication tool between a container
manager (like podman or CRI-O) and an OCI runtime (like runc or crun) for a
single container.
Upon being launched, it double-forks to daemonize and detach from the parent
that launched it. It then launches the runtime as its child. This allows
managing processes to die in the foreground, but still be able to watch over
and connect to the child process (the container).
While the container runs, conmon does two things:
Provides a socket for attaching to the container, holding open the
container's standard streams and forwarding them over the socket. Writes
the contents of the container's streams to a log file (or to the systemd
journal) so they can be read after the container's death.
Finally, upon the containers death, conmon will record its exit time and code
to be read by the managing programs.
Written in C and designed to have a low memory footprint, conmon is intended
to be run by a container managing library. Essentially, conmon is the smallest
daemon a container can have.
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