High-level ssh client library

There is no common ssh client library. Different projects use own functions, or ssh function from processutils, which is not flexible enough.

Paramiko is not the answer, because it too low-level. For example:

 import paramiko
 ssh = paramiko.SSHClient()
 ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
 ssh.connect('host', username='usef')
 ssh_stdin, ssh_stdout, ssh_stderr = ssh.exec_command('sh /root/outerr.sh')
 print ssh_stdout.read()
 print ssh_stderr.read()

In example above, if there is data on stderr which do not fit in buffer then we got deadlock on stdout reading.

If we want to receive stdout, stderr and exit status, we should write even more code.

Working with this library may look like this:

    ssh = sshclient.SSH('root', 'example.com', port=33)
    status, stdout, stderr = ssh.execute('ps ax')

Execute command with huge output:

    ssh = sshclient.SSH('root', 'example.com')
    def stdout_callback(data):
        LOG.debug(data)
    ssh.run('tail -f /var/log/syslog', stdout_callback=stdout_callback, timeout=False)

Execute local script on remote side:

    ssh = sshclient.SSH('user', 'example.com')
    status, out, err = ssh.execute('/bin/sh -e', stdin=open('~/myscript.sh', 'r'))

Potential library consumers:

ironic
quantum
savanna
tempest
heat

cinder uses own advanced ssh library
nova uses command line ssh