Create and communicate with process inside container

Question

I'm trying to use python to start a process inside of existing container and communicate with it.

What I have:

import docker
import os    
client = docker.APIClient()
buf = b"ls"
exec_setup = client.exec_create(container="some-tag", cmd="/bin/bash", stdin=True, tty=True)
socket = client.exec_start(exec_id = exec_setup["Id"], socket=True)
written = os.write(socket.fileno(), buf)
nxt = os.read(socket.fileno(), 1024)
print(nxt)

But when I run it I'm getting BlockingIOError: [Errno 11] Resource temporarily unavailable

Appreciate any help

Answer 1

Try attach_socket and set it into non-blocking mode.

params here is dict with params that you want to recv.

sock = client.attach_socket(cont, params=params)
sock._sock.setblocking(False)

After it use select in infinite loop to write/read from socket.

    buff = b''
    while True:
        read, write, _ = select.select([sock], [sock], [], 1)
        if read:
            try:
               data = socket_read(sock)
            except Exception:
               break
            if data is None:
               break
            stream_data += data

        if write and stdin:
            try:
               written = socket_write(sock, stdin)
            except Exception:
               break
            stdin = stdin[written:]

            if not stdin:
               sock._sock.shutdown(socket.SHUT_WR)

socket_read/socket_write here is function with os.read/os.write