在Python子进程中在docker中运行交互式命令

Question

When I use docker run in interactive mode I am able to run the commands I want to test some python stuff.

root@pydock:~# docker run -i -t dockerfile/python /bin/bash
[ root@197306c1b256:/data ]$ python -c "print 'hi there'"
hi there
[ root@197306c1b256:/data ]$ exit
exit
root@pydock:~#

I want to automate this from python using the subprocess module so I wrote this:

run_this = "print('hi')"
random_name = ''.join(random.SystemRandom().choice(string.ascii_uppercase + string.digits) for _ in range(20))
command = 'docker run -i -t --name="%s" dockerfile/python /bin/bash' % random_name
subprocess.call([command],shell=True,stderr=subprocess.STDOUT)
command = 'cat <<\'PYSTUFF\' | timeout 0.5 python | head -n 500000 \n%s\nPYSTUFF' % run_this
output = subprocess.check_output([command],shell=True,stderr=subprocess.STDOUT)
command = 'exit'
subprocess.call([command],shell=True,stderr=subprocess.STDOUT)
command = 'docker ps -a | grep "%s" | awk "{print $1}" | xargs --no-run-if-empty docker rm -f' % random_name
subprocess.call([command],shell=True,stderr=subprocess.STDOUT)

This is supposed to create the container, run the python command on the container and exit and remove the container. It does all this except the command is run on the host machine and not the docker container. I guess docker is switching shells or something like that. How do I run python subprocess from a new shell?

Answer 1

It looks like you are expecting the second command cat <<... to send input to the first command. But the two subprocess commands have nothing to do with each other, so this doesn't work.

Python's subprocess library , and the popen command that underlies it, offer a way to get a pipe to stdin of the process. This way, you can send in the commands you want directly from Python and don't have to attempt to get another subprocess to talk to it.

So, something like:

from subprocess import Popen, PIPE

p = Popen("docker run -i -t --name="%s" dockerfile/python /bin/bash", stdin=PIPE)
p.communicate("timeout 0.5 python | head -n 500000 \n" % run_this) 

(I'm not a Python expert; apologies for errors in string-forming. Adapted from this answer )

Answer 2

你实际上需要在你正在打开的新shell上生成一个新子。所以在docker creation运行pexpect docker enter或尝试使用pexpect而不是pexpect进行相同的操作pexpect生成一个新的子pexpect ，这样你就可以发送命令。