Pipeing using exec_create, exec_start stdin, stdout

If I use the docker CL this works perfectly for me.

echo "hello" | docker exec -i $3 sh -c 'cat >/text.txt'

Now I want to use docker-py and have this so far:

ex = cli.exec_create(container='nginx-ssl', cmd='cat >/carlskii.txt')
print cli.exec_inspect(ex)
ls = cli.exec_start(exec_id=ex["Id"], tty=True)

So how do I pass the "hello" or whatever data into the exec command so that it replicates the CL command ?

Incidentally this also works perfectly locally:

p = Popen(('docker', 'exec', '-i', 'nginx-ssl', 'sh', '-c', 'cat >text.txt'), stdin=subprocess.PIPE)
p.communicate('hello\n')
p.stdin.close()

Start with the exec_create and exec_start entry points shown in the issue, then read the surrounding docker-py documentation and the Docker Engine exec API behavior for stdin and output streams. Done means passing "hello" through the exec session produces the same file content as the docker CLI example.