[Chaos Mesh] RPC cross different namespaces through unix socket

[nate-double-u]

Communicate with subprocess in another namespace through unix socket.

The chaos-daemon component of Chaos Mesh manages many subprocesses to inject faults into other containers(Linux namespaces), and we need to communicate with the subprocesses (to modify configurations or monitor statuses). However, some of the subprocesses run in another network namespace (hard to access by network), others of them may run in another mount namespace (hard to access by named unix socket). Currently, chaos-daemon communicate with subprocesses by stdin and stdout, it works across different namespaces but lacks session layers, and we have to be cautious of printing logs into stdout. So, we need a better way to communicate with subprocesses, and the abstract unix socket is a reasonable choice.

Mentor(s): Hexilee (@Hexilee), Yang Keao (@YangKeao)

https://github.com/cncf/mentoring/blob/main/summerofcode/2022.md#rpc-cross-different-namespaces-through-unix-socket