Subprocess on remote server

Question

I am using this code for executing command on remote server.

import subprocess
import sys
COMMAND="ls"

ssh = subprocess.Popen(["ssh", "%s" % HOST, COMMAND],
                   shell=False,
                   stdout=subprocess.PIPE,
                   stderr=subprocess.PIPE)
result = ssh.stdout.readlines()
if result == []:
    error = ssh.stderr.readlines()
    print >>sys.stderr, "ERROR: %s" % error
else:
    print result

When I try to execute this script, I get prompt for password. Is there any way I could avoid it, for example, can I enter password in script somehow? Also, password should be encrypted somehow so that people who have access to the script cannot see it.

Answer 1

Why make it so complicated? Here's what I suggest:

1) Create a ssh config section in your ~/.ssh/config file:

Host myserver
  HostName 50.50.50.12 (fill in with your server's ip)
  Port xxxx (optional)
  User me (your username for server)

2) If you have generated your ssh keypair do it now (with ssh-keygen). Then upload with:

$ ssh-copy-id myserver

3) Now you can use subprocess with ssh. For example, to capture output, I call:

result = subprocess.check_output(['ssh', 'myserver', 'cat', 'somefile'])

Simple, robust, and the only time a password is needed is when you copy the public key to the server.

BTW, you code will probably work just fine as well using these steps.

Answer 2

One way is to create a public key, put it on the server, and do ssh -i /path/to/pub/key user@host or use paramiko like this:

import paramiko
import getpass

ssh = paramiko.SSHClient()

ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())

p = getpass.getpass()

ssh.connect('hostname', username='user', password=p)

stdin, stdout, stderr = ssh.exec_command('ls')
print stdout.readlines()
ssh.close()