Running python subprocess with shell=True with parameters

Question

I am trying to "port" the following linux shell command (that works fine):

docker run --name mycontainer myimage --detach -p 389:389 -p 689:689

to python with:

container_name="mycontainer"
image_name="myimage"
subprocess.check_call('docker run --name $container_name $image_name --detach -p 389:389 -p 689:689', shell=True)

But I get the error:

"docker run" requires at least 1 argument.
See 'docker run --help'.

Usage:  docker run [OPTIONS] IMAGE [COMMAND] [ARG...]

Run a command in a new container
Traceback (most recent call last):
  File "myscript.py", line 110, in <module>
    subprocess.check_call('docker run --name $container_name $image_name --detach -p 389:389 -p 689:689', shell=True)
  File "/usr/lib/python2.7/subprocess.py", line 186, in check_call
    raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command 'docker run --name $container_name --detach $image_name -p 389:389 -p 689:689' returned non-zero exit status 1

So the parameters are not resolved. Is it a no-go to use parameters like this when shell=True and if so what is the closest I can get to running "pure" shell commands from python?

You are setting Python variables named container_name and image_name. These are not shell variables and the shell knows nothing about them. Consider python string formatting ('--name {}'.format(container_name)). — larsks
– larsks, Commented Feb 3, 2018 at 15:26
There's another misconception in your question: There is no such thing as a "linux shell command". Shells have builtin commands but are otherwise used to launch other programs. None of this has to do with Linux (capital L, btw), it's the same on other systems, too. In this case, the program you want to invoke is docker. BTW: Consider using Python 3. — Ulrich Eckhardt
– Ulrich Eckhardt, Commented Feb 3, 2018 at 15:42

Mark Galeck · Accepted Answer · 2018-02-04 03:12:47Z

1

You cannot use $variable to evaluate variable in Python, this only works in shells. Do this instead:

subprocess.check_call('docker run --name ' + container_name + ' ' + image_name + ' --detach -p 389:389 -p 689:689', shell=True)

answered Feb 4, 2018 at 3:12

Mark Galeck

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