Source code for pas.shell

"""
Local and remote shell commands execution.

These functions are mainly wrappers around those found in the fabric library.
"""


from pas.conf import settings
from pas.conf import all_hosts

# pylint: disable-msg=W0611
# Disable warning about unused imports, as they are intended to be available
# directly from the shell module to avoid specific fabric imports

from fabric import state
from fabric.context_managers import settings as _context
from fabric.context_managers import hide as _hide
from fabric.context_managers import _setenv
from fabric.context_managers import nested as _nested
from fabric.context_managers import cd
from fabric.contrib.console import confirm
from fabric.operations import local as _local
from fabric.operations import run as _run
from fabric.operations import sudo as _sudo
from fabric.operations import prompt

# pylint: enable-msg=W0611


__all__ = [
    # shell module functions
    'ignore_warnings', 'workon', 'local', 'remote',
    
    # imported from the fabric library for external use
    'cd', 'prompt', 'confirm',
]


def ignore_warnings():
    """
    Returns a fabric context manager configured to silently ignore all
    warnings about running commands.
    """
    return _context(_hide('warnings'), warn_only=True)


def workon(hosts):
    """
    Returns a fabric context manager which sets the hosts list to the given
    list.
    
    If the passed hosts argument is a single string, it is silently converted
    to a list before.
    """
    if isinstance(hosts, basestring):
        hosts = [hosts]
    
    return _nested(_setenv(hosts=hosts))


def local(cmd):
    """
    Executes a local command without capturing and returning the output.
    
    Thin wraper around the fabric.operations.local function
    """
    return _local(cmd, capture=False)


def remote(cmd, pty=False, user=None, sudo=False):
    """
    Executes the given remote command on the hosts list set in the current
    context.
    
    If user is given or sudo evaluates to True, then a fabric.operations.sudo
    call is made, otherwise a simple fabric.operations.run.
    """
    if state.env.cwd:
        cmd = 'cd {0} && {1}'.format(state.env.cwd, cmd)
    
    with _context(user=settings.VM_USER, password=settings.VM_PASSWORD):
        for host in state.env.hosts or all_hosts():
            with _context(host_string=host):
                if user or sudo:
                    _sudo(cmd, user=user, pty=pty)
                else:
                    _run(cmd, pty=pty)