Script to find out which container is running the process

which-container.py

#!/usr/bin/python3
import re
import sys
import docker

ID_PATTERN = re.compile("[0-9a-f]{12}")
DOCKER_CONTAINERS = docker.from_env().containers


def get_ppid(pid: int) -> int:
    try:
        with open(f"/proc/{pid}/status") as f:
            for line in f:
                key, value = line.strip().split(":")[:2]
                if key == "PPid":
                    return int(value)
    except FileNotFoundError:
        print(f"process {pid} does not exist")
        exit(1)


def get_cmdline(pid: int) -> str:
    try:
        with open(f"/proc/{pid}/cmdline") as f:
            return f.read()
    except FileNotFoundError:
        print(f"process {pid} does not exist")
        exit(1)


def find_root(pid: int) -> int:
    if pid == 1:
        return 1
    else:
        if "containerd-shim" in get_cmdline(pid):
            return pid
        else:
            return find_root(get_ppid(pid))


def root_info(pid: int) -> None:
    root = find_root(pid)
    if root == 1:
        print(f"process {pid} is not running in docker")
    else:
        cid = ID_PATTERN.search(get_cmdline(root)).group(0)
        name = DOCKER_CONTAINERS.get(cid).attrs['Name']
        print(f"process {pid} is running in docker {cid}:{name}")


if __name__ == "__main__":
    if len(sys.argv) > 1:
        for pid in sys.argv[1:]:
            root_info(int(pid))
    else:
        root_info(int(input("pid\n>>> ")))