path: root/lib/ansible/runner/__init__.py

# (c) 2012-2014, Michael DeHaan <michael.dehaan@gmail.com>
#
# This file is part of Ansible
#
# Ansible is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Ansible is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Ansible.  If not, see <http://www.gnu.org/licenses/>.

import multiprocessing
import signal
import os
import pwd
import Queue
import random
import traceback
import tempfile
import time
import collections
import socket
import base64
import sys
import shlex
import pipes
import jinja2
import subprocess

import ansible.constants as C
import ansible.inventory
from ansible import utils
from ansible.utils import template
from ansible.utils import check_conditional
from ansible.utils import string_functions
from ansible import errors
from ansible import module_common
import poller
import connection
from return_data import ReturnData
from ansible.callbacks import DefaultRunnerCallbacks, vv
from ansible.module_common import ModuleReplacer

module_replacer = ModuleReplacer(strip_comments=False)

NEED_ATFORK=False
HAS_ATFORK=True
try:
    from Crypto.Random import atfork
except ImportError:
    HAS_ATFORK=False

multiprocessing_runner = None
        
OUTPUT_LOCKFILE  = tempfile.TemporaryFile()
PROCESS_LOCKFILE = tempfile.TemporaryFile()

from foon import Foon

FOON = Foon()

################################################

class KeyboardInterruptError(Exception):
    pass

def _executor_hook(params):

    (host, my_stdin) = params

    # attempt workaround of https://github.com/newsapps/beeswithmachineguns/issues/17
    # this function also not present in CentOS 6
    if HAS_ATFORK and NEED_ATFORK:
        atfork()

    try:
        return multiprocessing_runner._executor(host, my_stdin)
    except KeyboardInterrupt:
        raise KeyboardInterruptError()

class HostVars(dict):
    ''' A special view of setup_cache that adds values from the inventory when needed. '''

    def __init__(self, setup_cache, inventory):
        self.setup_cache = setup_cache
        self.inventory = inventory
        self.lookup = dict()
        self.update(setup_cache)

    def __getitem__(self, host):
        if host not in self.lookup:
            result = self.inventory.get_variables(host)
            result.update(self.setup_cache.get(host, {}))
            self.lookup[host] = result
        return self.lookup[host]


class Runner(object):
    ''' core API interface to ansible '''

    # see bin/ansible for how this is used...

    def __init__(self,
        host_list=C.DEFAULT_HOST_LIST,      # ex: /etc/ansible/hosts, legacy usage
        module_path=None,                   # ex: /usr/share/ansible
        module_name=C.DEFAULT_MODULE_NAME,  # ex: copy
        module_args=C.DEFAULT_MODULE_ARGS,  # ex: "src=/tmp/a dest=/tmp/b"
        forks=C.DEFAULT_FORKS,              # parallelism level
        timeout=C.DEFAULT_TIMEOUT,          # SSH timeout
        pattern=C.DEFAULT_PATTERN,          # which hosts?  ex: 'all', 'acme.example.org'
        remote_user=C.DEFAULT_REMOTE_USER,  # ex: 'username'
        remote_pass=C.DEFAULT_REMOTE_PASS,  # ex: 'password123' or None if using key
        remote_port=None,                   # if SSH on different ports
        private_key_file=C.DEFAULT_PRIVATE_KEY_FILE, # if not using keys/passwords
        sudo_pass=C.DEFAULT_SUDO_PASS,      # ex: 'password123' or None
        background=0,                       # async poll every X seconds, else 0 for non-async
        basedir=None,                       # directory of playbook, if applicable
        setup_cache=None,                   # used to share fact data w/ other tasks
        transport=C.DEFAULT_TRANSPORT,      # 'ssh', 'paramiko', 'local'
        conditional='True',                 # run only if this fact expression evals to true
        callbacks=None,                     # used for output
        sudo=False,                         # whether to run sudo or not
        sudo_user=C.DEFAULT_SUDO_USER,      # ex: 'root'
        module_vars=None,                   # a playbooks internals thing
        default_vars=None,                  # ditto
        is_playbook=False,                  # running from playbook or not?
        inventory=None,                     # reference to Inventory object
        subset=None,                        # subset pattern
        check=False,                        # don't make any changes, just try to probe for potential changes
        diff=False,                         # whether to show diffs for template files that change
        environment=None,                   # environment variables (as dict) to use inside the command
        complex_args=None,                  # structured data in addition to module_args, must be a dict
        error_on_undefined_vars=C.DEFAULT_UNDEFINED_VAR_BEHAVIOR, # ex. False
        accelerate=False,                   # use accelerated connection
        accelerate_ipv6=False,              # accelerated connection w/ IPv6
        accelerate_port=None,               # port to use with accelerated connection
        su=False,                           # Are we running our command via su?
        su_user=None,                       # User to su to when running command, ex: 'root'
        su_pass=C.DEFAULT_SU_PASS,
        run_hosts=None,                     # an optional list of pre-calculated hosts to run on
        no_log=False,                       # option to enable/disable logging for a given task
        ):

        # used to lock multiprocess inputs and outputs at various levels
        self.output_lockfile  = OUTPUT_LOCKFILE
        self.process_lockfile = PROCESS_LOCKFILE

        if not complex_args:
            complex_args = {}

        # storage & defaults
        self.check            = check
        self.diff             = diff
        self.setup_cache      = utils.default(setup_cache, lambda: collections.defaultdict(dict))
        self.basedir          = utils.default(basedir, lambda: os.getcwd())
        self.callbacks        = utils.default(callbacks, lambda: DefaultRunnerCallbacks())
        self.generated_jid    = str(random.randint(0, 999999999999))
        self.transport        = transport
        self.inventory        = utils.default(inventory, lambda: ansible.inventory.Inventory(host_list))

        self.module_vars      = utils.default(module_vars, lambda: {})
        self.default_vars     = utils.default(default_vars, lambda: {})
        self.always_run       = None
        self.connector        = connection.Connection(self)
        self.conditional      = conditional
        self.module_name      = module_name
        self.forks            = int(forks)
        self.pattern          = pattern
        self.module_args      = module_args
        self.timeout          = timeout
        self.remote_user      = remote_user
        self.remote_pass      = remote_pass
        self.remote_port      = remote_port
        self.private_key_file = private_key_file
        self.background       = background
        self.sudo             = sudo
        self.sudo_user_var    = sudo_user
        self.sudo_user        = None
        self.sudo_pass        = sudo_pass
        self.is_playbook      = is_playbook
        self.environment      = environment
        self.complex_args     = complex_args
        self.error_on_undefined_vars = error_on_undefined_vars
        self.accelerate       = accelerate
        self.accelerate_port  = accelerate_port
        self.accelerate_ipv6  = accelerate_ipv6
        self.callbacks.runner = self
        self.original_transport = self.transport
        self.su               = su
        self.su_user_var      = su_user
        self.su_user          = None
        self.su_pass          = su_pass
        self.no_log           = no_log

        if self.transport == 'smart':
            # if the transport is 'smart' see if SSH can support ControlPersist if not use paramiko
            # 'smart' is the default since 1.2.1/1.3
            cmd = subprocess.Popen(['ssh','-o','ControlPersist'], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
            (out, err) = cmd.communicate() 
            if "Bad configuration option" in err:
                self.transport = "paramiko"
            else:
                self.transport = "ssh" 

        if self.transport == "paramiko":
            global NEED_ATFORK
            NEED_ATFORK=True

        # misc housekeeping
        if subset and self.inventory._subset is None:
            # don't override subset when passed from playbook
            self.inventory.subset(subset)

        # If we get a pre-built list of hosts to run on, from say a playbook, use them.
        # Also where we will store the hosts to run on once discovered
        self.run_hosts = run_hosts

        if self.transport == 'local':
            self.remote_user = pwd.getpwuid(os.geteuid())[0]

        if module_path is not None:
            for i in module_path.split(os.pathsep):
                utils.plugins.module_finder.add_directory(i)

        utils.plugins.push_basedir(self.basedir)

        # ensure we are using unique tmp paths
        random.seed()
    # *****************************************************

    def _complex_args_hack(self, complex_args, module_args):
        """
        ansible-playbook both allows specifying key=value string arguments and complex arguments
        however not all modules use our python common module system and cannot
        access these.  An example might be a Bash module.  This hack allows users to still pass "args"
        as a hash of simple scalars to those arguments and is short term.  We could technically
        just feed JSON to the module, but that makes it hard on Bash consumers.  The way this is implemented
        it does mean values in 'args' have LOWER priority than those on the key=value line, allowing
        args to provide yet another way to have pluggable defaults.
        """
        if complex_args is None:
            return module_args
        if type(complex_args) != dict:
            raise errors.AnsibleError("complex arguments are not a dictionary: %s" % complex_args)
        for (k,v) in complex_args.iteritems():
            if isinstance(v, basestring):
                module_args = "%s=%s %s" % (k, pipes.quote(v), module_args)
        return module_args

    # *****************************************************

    def _transfer_str(self, conn, tmp, name, data):
        ''' transfer string to remote file '''

        if type(data) == dict:
            data = utils.jsonify(data)

        afd, afile = tempfile.mkstemp()
        afo = os.fdopen(afd, 'w')
        try:
            if not isinstance(data, unicode):
                #ensure the data is valid UTF-8
                data.decode('utf-8')
            else:
                data = data.encode('utf-8')
            afo.write(data)
        except:
            raise errors.AnsibleError("failure encoding into utf-8")
        afo.flush()
        afo.close()

        remote = os.path.join(tmp, name)
        try:
            conn.put_file(afile, remote)
        finally:
            os.unlink(afile)
        return remote

    # *****************************************************

    def _compute_environment_string(self, inject=None):
        ''' what environment variables to use when running the command? '''

        if not self.environment:
            return ""
        enviro = template.template(self.basedir, self.environment, inject, convert_bare=True)
        enviro = utils.safe_eval(enviro)
        if type(enviro) != dict:
            raise errors.AnsibleError("environment must be a dictionary, received %s" % enviro)
        result = ""
        for (k,v) in enviro.iteritems():
            result = "%s=%s %s" % (k, pipes.quote(str(v)), result)
        return result

    # *****************************************************

    def _compute_delegate(self, host, password, remote_inject):

        """ Build a dictionary of all attributes for the delegate host """
       
        delegate = {}

        # allow ansible_ssh_host to be templated
        delegate['host'] = template.template(self.basedir, host, 
                                remote_inject, fail_on_undefined=True)

        delegate['inject'] = remote_inject.copy()

        # set any interpreters
        interpreters = []
        for i in delegate['inject']:
            if i.startswith("ansible_") and i.endswith("_interpreter"):
                interpreters.append(i)
        for i in interpreters:
            del delegate['inject'][i]
        port = C.DEFAULT_REMOTE_PORT

        this_host = delegate['host']

        # get the vars for the delegate by it's name        
        this_info = delegate['inject']['hostvars'][this_host]

        # get the real ssh_address for the delegate        
        delegate['ssh_host'] = this_info.get('ansible_ssh_host', delegate['host'])

        delegate['port'] = this_info.get('ansible_ssh_port', port)
        delegate['user'] = self._compute_delegate_user(this_host, delegate['inject'])
        delegate['pass'] = this_info.get('ansible_ssh_pass', password)
        delegate['private_key_file'] = this_info.get('ansible_ssh_private_key_file', 
                                        self.private_key_file)
        delegate['transport'] = this_info.get('ansible_connection', self.transport)
        delegate['sudo_pass'] = this_info.get('ansible_sudo_pass', self.sudo_pass)

        if delegate['private_key_file'] is not None:
            delegate['private_key_file'] = os.path.expanduser(delegate['private_key_file'])

        for i in this_info:
            if i.startswith("ansible_") and i.endswith("_interpreter"):
                delegate['inject'][i] = this_info[i]

        return delegate

    def _compute_delegate_user(self, host, inject):

        """ Caculate the remote user based on an order of preference """

        # inventory > playbook > original_host

        actual_user = inject.get('ansible_ssh_user', self.remote_user)
        thisuser = None

        if inject['hostvars'][host].get('ansible_ssh_user'):
            # user for delegate host in inventory
            thisuser = inject['hostvars'][host].get('ansible_ssh_user')
        if thisuser is None and self.remote_user:
            # user defined by play/runner
            thisuser = self.remote_user

        if thisuser is not None:
            actual_user = thisuser
        else:
            # fallback to the inventory user of the play host
            #actual_user = inject.get('ansible_ssh_user', actual_user)
            actual_user = inject.get('ansible_ssh_user', self.remote_user)

        return actual_user


    # *****************************************************

    def _execute_module(self, conn, tmp, module_name, args,
        async_jid=None, async_module=None, async_limit=None, inject=None, persist_files=False, complex_args=None, delete_remote_tmp=True):

        ''' transfer and run a module along with its arguments on the remote side'''

        # hack to support fireball mode
        if module_name == 'fireball':
            args = "%s password=%s" % (args, base64.b64encode(str(utils.key_for_hostname(conn.host))))
            if 'port' not in args:
                args += " port=%s" % C.ZEROMQ_PORT

        (
        module_style,
        shebang,
        module_data
        ) = self._configure_module(conn, module_name, args, inject, complex_args)

        # a remote tmp path may be necessary and not already created
        if self._late_needs_tmp_path(conn, tmp, module_style):
            tmp = self._make_tmp_path(conn)

        remote_module_path = os.path.join(tmp, module_name)

        if (module_style != 'new'
           or async_jid is not None
           or not conn.has_pipelining
           or not C.ANSIBLE_SSH_PIPELINING
           or C.DEFAULT_KEEP_REMOTE_FILES
           or self.su):
            self._transfer_str(conn, tmp, module_name, module_data)

        environment_string = self._compute_environment_string(inject)

        if tmp.find("tmp") != -1 and (self.sudo or self.su) and (self.sudo_user != 'root' or self.su_user != 'root'):
            # deal with possible umask issues once sudo'ed to other user
            cmd_chmod = "chmod a+r %s" % remote_module_path
            self._low_level_exec_command(conn, cmd_chmod, tmp, sudoable=False)

        cmd = ""
        in_data = None
        if module_style != 'new':
            if 'CHECKMODE=True' in args:
                # if module isn't using AnsibleModuleCommon infrastructure we can't be certain it knows how to
                # do --check mode, so to be safe we will not run it.
                return ReturnData(conn=conn, result=dict(skipped=True, msg="cannot yet run check mode against old-style modules"))
            elif 'NO_LOG' in args:
                return ReturnData(conn=conn, result=dict(skipped=True, msg="cannot use no_log: with old-style modules"))

            args = template.template(self.basedir, args, inject)

            # decide whether we need to transfer JSON or key=value
            argsfile = None
            if module_style == 'non_native_want_json':
                if complex_args:
                    complex_args.update(utils.parse_kv(args))
                    argsfile = self._transfer_str(conn, tmp, 'arguments', utils.jsonify(complex_args))
                else:
                    argsfile = self._transfer_str(conn, tmp, 'arguments', utils.jsonify(utils.parse_kv(args)))

            else:
                argsfile = self._transfer_str(conn, tmp, 'arguments', args)

            if (self.sudo or self.su) and (self.sudo_user != 'root' or self.su_user != 'root'):
                # deal with possible umask issues once sudo'ed to other user
                cmd_args_chmod = "chmod a+r %s" % argsfile
                self._low_level_exec_command(conn, cmd_args_chmod, tmp, sudoable=False)

            if async_jid is None:
                cmd = "%s %s" % (remote_module_path, argsfile)
            else:
                cmd = " ".join([str(x) for x in [remote_module_path, async_jid, async_limit, async_module, argsfile]])
        else:
            if async_jid is None:
                if conn.has_pipelining and C.ANSIBLE_SSH_PIPELINING and not C.DEFAULT_KEEP_REMOTE_FILES and not self.su:
                    in_data = module_data
                else:
                    cmd = "%s" % (remote_module_path)
            else:
                cmd = " ".join([str(x) for x in [remote_module_path, async_jid, async_limit, async_module]])

        if not shebang:
            raise errors.AnsibleError("module is missing interpreter line")


        cmd = " ".join([environment_string.strip(), shebang.replace("#!","").strip(), cmd])
        cmd = cmd.strip()

        if tmp.find("tmp") != -1 and not C.DEFAULT_KEEP_REMOTE_FILES and not persist_files and delete_remote_tmp:
            if not self.sudo or self.su or self.sudo_user == 'root' or self.su_user == 'root':
                # not sudoing or sudoing to root, so can cleanup files in the same step
                cmd = cmd + "; rm -rf %s >/dev/null 2>&1" % tmp

        sudoable = True
        if module_name == "accelerate":
            # always run the accelerate module as the user
            # specified in the play, not the sudo_user
            sudoable = False

        if self.su:
            res = self._low_level_exec_command(conn, cmd, tmp, su=True, in_data=in_data)
        else:
            res = self._low_level_exec_command(conn, cmd, tmp, sudoable=sudoable, in_data=in_data)

        if tmp.find("tmp") != -1 and not C.DEFAULT_KEEP_REMOTE_FILES and not persist_files and delete_remote_tmp:
            if (self.sudo or self.su) and (self.sudo_user != 'root' or self.su_user != 'root'):
            # not sudoing to root, so maybe can't delete files as that other user
            # have to clean up temp files as original user in a second step
                cmd2 = "rm -rf %s >/dev/null 2>&1" % tmp
                self._low_level_exec_command(conn, cmd2, tmp, sudoable=False)

        data = utils.parse_json(res['stdout'])
        if 'parsed' in data and data['parsed'] == False:
            data['msg'] += res['stderr']
        return ReturnData(conn=conn, result=data)

    # *****************************************************

    def _executor(self, host, new_stdin):
        ''' handler for multiprocessing library '''

        def get_flags():
            # flags are a way of passing arbitrary event information
            # back up the chain, since multiprocessing forks and doesn't
            # allow state exchange
            flags = []
            if template.Flags.LEGACY_TEMPLATE_WARNING:
                flags.append('LEGACY_TEMPLATE_WARNING')
            return flags

        try:
            fileno = sys.stdin.fileno()
        except ValueError:
            fileno = None

        try:
            if not new_stdin and fileno is not None:
                self._new_stdin = os.fdopen(os.dup(fileno))
            else:
                self._new_stdin = new_stdin

            exec_rc = self._executor_internal(host, new_stdin)
            if type(exec_rc) != ReturnData:
                raise Exception("unexpected return type: %s" % type(exec_rc))
            exec_rc.flags = get_flags()
            # redundant, right?
            if not exec_rc.comm_ok:
                self.callbacks.on_unreachable(host, exec_rc.result)
            return exec_rc
        except errors.AnsibleError, ae:
            msg = str(ae)
            self.callbacks.on_unreachable(host, msg)
            return ReturnData(host=host, comm_ok=False, result=dict(failed=True, msg=msg), flags=get_flags())
        except Exception:
            msg = traceback.format_exc()
            self.callbacks.on_unreachable(host, msg)
            return ReturnData(host=host, comm_ok=False, result=dict(failed=True, msg=msg), flags=get_flags())

    # *****************************************************

    def _executor_internal(self, host, new_stdin):
        ''' executes any module one or more times '''

        host_variables = self.inventory.get_variables(host)
        host_connection = host_variables.get('ansible_connection', self.transport)
        if host_connection in [ 'paramiko', 'paramiko_alt', 'ssh', 'ssh_old', 'accelerate' ]:
            port = host_variables.get('ansible_ssh_port', self.remote_port)
            if port is None:
                port = C.DEFAULT_REMOTE_PORT
        else:
            # fireball, local, etc
            port = self.remote_port

        inject = {}
        inject = utils.combine_vars(inject, self.default_vars)
        inject = utils.combine_vars(inject, host_variables)
        inject = utils.combine_vars(inject, self.module_vars)
        inject = utils.combine_vars(inject, self.setup_cache[host])
        inject.setdefault('ansible_ssh_user', self.remote_user)
        inject['hostvars'] = HostVars(self.setup_cache, self.inventory)
        inject['group_names'] = host_variables.get('group_names', [])
        inject['groups']      = self.inventory.groups_list()
        inject['vars']        = self.module_vars
        inject['defaults']    = self.default_vars
        inject['environment'] = self.environment
        inject['playbook_dir'] = self.basedir

        if self.inventory.basedir() is not None:
            inject['inventory_dir'] = self.inventory.basedir()

        if self.inventory.src() is not None:
            inject['inventory_file'] = self.inventory.src()

        # allow with_foo to work in playbooks...
        items = None
        items_plugin = self.module_vars.get('items_lookup_plugin', None)

        if items_plugin is not None and items_plugin in utils.plugins.lookup_loader:

            basedir = self.basedir
            if '_original_file' in inject:
                basedir = os.path.dirname(inject['_original_file'])
                filesdir = os.path.join(basedir, '..', 'files')
                if os.path.exists(filesdir):
                    basedir = filesdir

            items_terms = self.module_vars.get('items_lookup_terms', '')
            items_terms = template.template(basedir, items_terms, inject)
            items = utils.plugins.lookup_loader.get(items_plugin, runner=self, basedir=basedir).run(items_terms, inject=inject)
            if type(items) != list:
                raise errors.AnsibleError("lookup plugins have to return a list: %r" % items)

            if len(items) and utils.is_list_of_strings(items) and self.module_name in [ 'apt', 'yum', 'pkgng' ]:
                # hack for apt, yum, and pkgng so that with_items maps back into a single module call
                use_these_items = []
                for x in items:
                    inject['item'] = x
                    if not self.conditional or utils.check_conditional(self.conditional, self.basedir, inject, fail_on_undefined=self.error_on_undefined_vars):
                        use_these_items.append(x)
                inject['item'] = ",".join(use_these_items)
                items = None

        # logic to replace complex args if possible
        complex_args = self.complex_args

        # logic to decide how to run things depends on whether with_items is used
        if items is None:
            if isinstance(complex_args, basestring):
                complex_args = template.template(self.basedir, complex_args, inject, convert_bare=True)
                complex_args = utils.safe_eval(complex_args)
                if type(complex_args) != dict:
                    raise errors.AnsibleError("args must be a dictionary, received %s" % complex_args)
            return self._executor_internal_inner(host, self.module_name, self.module_args, inject, port, complex_args=complex_args)
        elif len(items) > 0:

            # executing using with_items, so make multiple calls
            # TODO: refactor

            if self.background > 0:
                raise errors.AnsibleError("lookup plugins (with_*) cannot be used with async tasks")

            aggregrate = {}
            all_comm_ok = True
            all_changed = False
            all_failed = False
            results = []
            for x in items:
                inject['item'] = x

                # TODO: this idiom should be replaced with an up-conversion to a Jinja2 template evaluation
                if isinstance(self.complex_args, basestring):
                    complex_args = template.template(self.basedir, self.complex_args, inject, convert_bare=True)
                    complex_args = utils.safe_eval(complex_args)
                    if type(complex_args) != dict:
                        raise errors.AnsibleError("args must be a dictionary, received %s" % complex_args)
                result = self._executor_internal_inner(
                     host,
                     self.module_name,
                     self.module_args,
                     inject,
                     port,
                     complex_args=complex_args
                )
                results.append(result.result)
                if result.comm_ok == False:
                    all_comm_ok = False
                    all_failed = True
                    break
                for x in results:
                    if x.get('changed') == True:
                        all_changed = True
                    if (x.get('failed') == True) or ('failed_when_result' in x and [x['failed_when_result']] or [('rc' in x) and (x['rc'] != 0)])[0]:
                        all_failed = True
                        break
            msg = 'All items completed'
            if all_failed:
                msg = "One or more items failed."
            rd_result = dict(failed=all_failed, changed=all_changed, results=results, msg=msg)
            if not all_failed:
                del rd_result['failed']
            return ReturnData(host=host, comm_ok=all_comm_ok, result=rd_result)
        else:
            self.callbacks.on_skipped(host, None)
            return ReturnData(host=host, comm_ok=True, result=dict(changed=False, skipped=True))

    # *****************************************************

    def _executor_internal_inner(self, host, module_name, module_args, inject, port, is_chained=False, complex_args=None):
        ''' decides how to invoke a module '''

        # late processing of parameterized sudo_user (with_items,..)
        if self.sudo_user_var is not None:
            self.sudo_user = template.template(self.basedir, self.sudo_user_var, inject)
        if self.su_user_var is not None:
            self.su_user = template.template(self.basedir, self.su_user_var, inject)

        # allow module args to work as a dictionary
        # though it is usually a string
        new_args = ""
        if type(module_args) == dict:
            for (k,v) in module_args.iteritems():
                new_args = new_args + "%s='%s' " % (k,v)
            module_args = new_args

        # module_name may be dynamic (but cannot contain {{ ansible_ssh_user }})
        module_name  = template.template(self.basedir, module_name, inject)

        if module_name in utils.plugins.action_loader:
            if self.background != 0:
                raise errors.AnsibleError("async mode is not supported with the %s module" % module_name)
            handler = utils.plugins.action_loader.get(module_name, self)
        elif self.background == 0:
            handler = utils.plugins.action_loader.get('normal', self)
        else:
            handler = utils.plugins.action_loader.get('async', self)

        if type(self.conditional) != list:
            self.conditional = [ self.conditional ]

        for cond in self.conditional:

            if not utils.check_conditional(cond, self.basedir, inject, fail_on_undefined=self.error_on_undefined_vars):
                result = utils.jsonify(dict(changed=False, skipped=True))
                self.callbacks.on_skipped(host, inject.get('item',None))
                return ReturnData(host=host, result=result)

        if getattr(handler, 'setup', None) is not None:
            handler.setup(module_name, inject)
        conn = None
        actual_host = inject.get('ansible_ssh_host', host)
        # allow ansible_ssh_host to be templated
        actual_host = template.template(self.basedir, actual_host, inject, fail_on_undefined=True)
        actual_port = port
        actual_user = inject.get('ansible_ssh_user', self.remote_user)
        actual_pass = inject.get('ansible_ssh_pass', self.remote_pass)
        actual_transport = inject.get('ansible_connection', self.transport)
        actual_private_key_file = inject.get('ansible_ssh_private_key_file', self.private_key_file)
        self.sudo_pass = inject.get('ansible_sudo_pass', self.sudo_pass)
        self.su = inject.get('ansible_su', self.su)
        self.su_pass = inject.get('ansible_su_pass', self.su_pass)

        if actual_private_key_file is not None:
            actual_private_key_file = os.path.expanduser(actual_private_key_file)

        if self.accelerate and actual_transport != 'local':
            #Fix to get the inventory name of the host to accelerate plugin
            if inject.get('ansible_ssh_host', None):
                self.accelerate_inventory_host = host
            else:
                self.accelerate_inventory_host = None
            # if we're using accelerated mode, force the
            # transport to accelerate
            actual_transport = "accelerate"
            if not self.accelerate_port:
                self.accelerate_port = C.ACCELERATE_PORT

        if actual_transport in [ 'paramiko', 'paramiko_alt', 'ssh', 'ssh_old', 'accelerate' ]:
            actual_port = inject.get('ansible_ssh_port', port)

        # the delegated host may have different SSH port configured, etc
        # and we need to transfer those, and only those, variables
        delegate_to = inject.get('delegate_to', None)
        if delegate_to is not None:
            delegate = self._compute_delegate(delegate_to, actual_pass, inject)
            actual_transport = delegate['transport']
            actual_host = delegate['ssh_host']
            actual_port = delegate['port']
            actual_user = delegate['user']
            actual_pass = delegate['pass']
            actual_private_key_file = delegate['private_key_file']
            self.sudo_pass = delegate['sudo_pass']
            inject = delegate['inject']

        # user/pass may still contain variables at this stage
        actual_user = template.template(self.basedir, actual_user, inject)
        actual_pass = template.template(self.basedir, actual_pass, inject)

        # make actual_user available as __magic__ ansible_ssh_user variable
        inject['ansible_ssh_user'] = actual_user

        try:
            if actual_transport == 'accelerate':
                # for accelerate, we stuff both ports into a single
                # variable so that we don't have to mangle other function
                # calls just to accomodate this one case
                actual_port = [actual_port, self.accelerate_port]
            elif actual_port is not None:
                actual_port = int(template.template(self.basedir, actual_port, inject))
        except ValueError, e:
            result = dict(failed=True, msg="FAILED: Configured port \"%s\" is not a valid port, expected integer" % actual_port)
            return ReturnData(host=host, comm_ok=False, result=result)

        try:
            conn = self.connector.connect(actual_host, actual_port, actual_user, actual_pass, actual_transport, actual_private_key_file)
            if delegate_to or host != actual_host:
                conn.delegate = host


        except errors.AnsibleConnectionFailed, e:
            result = dict(failed=True, msg="FAILED: %s" % str(e))
            return ReturnData(host=host, comm_ok=False, result=result)

        tmp = ''
        # action plugins may DECLARE via TRANSFERS_FILES = True that they need a remote tmp path working dir
        if self._early_needs_tmp_path(module_name, handler):
            tmp = self._make_tmp_path(conn)

        # render module_args and complex_args templates
        try:
            module_args = template.template(self.basedir, module_args, inject, fail_on_undefined=self.error_on_undefined_vars)
            complex_args = template.template(self.basedir, complex_args, inject, fail_on_undefined=self.error_on_undefined_vars)
        except jinja2.exceptions.UndefinedError, e:
            raise errors.AnsibleUndefinedVariable("One or more undefined variables: %s" % str(e))


        result = handler.run(conn, tmp, module_name, module_args, inject, complex_args)
        # Code for do until feature
        until = self.module_vars.get('until', None)
        if until is not None and result.comm_ok:
            inject[self.module_vars.get('register')] = result.result
            cond = template.template(self.basedir, until, inject, expand_lists=False)
            if not utils.check_conditional(cond,  self.basedir, inject, fail_on_undefined=self.error_on_undefined_vars):
                retries = self.module_vars.get('retries')
                delay   = self.module_vars.get('delay')
                for x in range(1, int(retries) + 1):
                    # template the delay, cast to float and sleep
                    delay = template.template(self.basedir, delay, inject, expand_lists=False)
                    delay = float(delay)
                    time.sleep(delay)
                    tmp = ''
                    if self._early_needs_tmp_path(module_name, handler):
                        tmp = self._make_tmp_path(conn)
                    result = handler.run(conn, tmp, module_name, module_args, inject, complex_args)
                    result.result['attempts'] = x
                    vv("Result from run %i is: %s" % (x, result.result))
                    inject[self.module_vars.get('register')] = result.result
                    cond = template.template(self.basedir, until, inject, expand_lists=False)
                    if utils.check_conditional(cond, self.basedir, inject, fail_on_undefined=self.error_on_undefined_vars):
                        break
                if result.result['attempts'] == retries and not utils.check_conditional(cond, self.basedir, inject, fail_on_undefined=self.error_on_undefined_vars):
                    result.result['failed'] = True 
                    result.result['msg'] = "Task failed as maximum retries was encountered"
            else:
                result.result['attempts'] = 0
        conn.close()

        if not result.comm_ok:
            # connection or parsing errors...
            self.callbacks.on_unreachable(host, result.result)
        else:
            data = result.result

            # https://github.com/ansible/ansible/issues/4958
            if hasattr(sys.stdout, "isatty"):
                if "stdout" in data and sys.stdout.isatty():
                    if not string_functions.isprintable(data['stdout']):
                        data['stdout'] = ''

            if 'item' in inject:
                result.result['item'] = inject['item']

            result.result['invocation'] = dict(
                module_args=module_args,
                module_name=module_name
            )

            changed_when = self.module_vars.get('changed_when')
            failed_when = self.module_vars.get('failed_when')
            if changed_when is not None or failed_when is not None:
                register = self.module_vars.get('register')
                if  register is not None:
                    if 'stdout' in data:
                        data['stdout_lines'] = data['stdout'].splitlines()
                    inject[register] = data
                if changed_when is not None:
                    data['changed'] = utils.check_conditional(changed_when, self.basedir, inject, fail_on_undefined=self.error_on_undefined_vars)
                if failed_when is not None:
                    data['failed_when_result'] = data['failed'] = utils.check_conditional(failed_when, self.basedir, inject, fail_on_undefined=self.error_on_undefined_vars)

            if is_chained:
                # no callbacks
                return result
            if 'skipped' in data:
                self.callbacks.on_skipped(host)
            elif not result.is_successful():
                ignore_errors = self.module_vars.get('ignore_errors', False)
                self.callbacks.on_failed(host, data, ignore_errors)
            else:
                if self.diff:
                    self.callbacks.on_file_diff(conn.host, result.diff)
                self.callbacks.on_ok(host, data)
        return result

    def _early_needs_tmp_path(self, module_name, handler):
        ''' detect if a tmp path should be created before the handler is called '''
        if module_name in utils.plugins.action_loader:
          return getattr(handler, 'TRANSFERS_FILES', False)
        # other modules never need tmp path at early stage
        return False

    def _late_needs_tmp_path(self, conn, tmp, module_style):
        if tmp.find("tmp") != -1:
            # tmp has already been created
            return False
        if not conn.has_pipelining or not C.ANSIBLE_SSH_PIPELINING or C.DEFAULT_KEEP_REMOTE_FILES or self.su:
            # tmp is necessary to store module source code
            return True
        if not conn.has_pipelining:
            # tmp is necessary to store the module source code
            # or we want to keep the files on the target system
            return True
        if module_style != "new":
            # even when conn has pipelining, old style modules need tmp to store arguments
            return True
        return False
    

    # *****************************************************

    def _low_level_exec_command(self, conn, cmd, tmp, sudoable=False,
                                executable=None, su=False, in_data=None):
        ''' execute a command string over SSH, return the output '''

        if executable is None:
            executable = C.DEFAULT_EXECUTABLE

        sudo_user = self.sudo_user
        su_user = self.su_user

        # compare connection user to (su|sudo)_user and disable if the same
        if hasattr(conn, 'user'):
            if conn.user == sudo_user or conn.user == su_user:
                sudoable = False
                su = False

        if su:
            rc, stdin, stdout, stderr = conn.exec_command(cmd,
                                                          tmp,
                                                          su=su,
                                                          su_user=su_user,
                                                          executable=executable,
                                                          in_data=in_data)
        else:
            rc, stdin, stdout, stderr = conn.exec_command(cmd,
                                                          tmp,
                                                          sudo_user,
                                                          sudoable=sudoable,
                                                          executable=executable,
                                                          in_data=in_data)

        if type(stdout) not in [ str, unicode ]:
            out = ''.join(stdout.readlines())
        else:
            out = stdout

        if type(stderr) not in [ str, unicode ]:
            err = ''.join(stderr.readlines())
        else:
            err = stderr

        if rc is not None:
            return dict(rc=rc, stdout=out, stderr=err)
        else:
            return dict(stdout=out, stderr=err)

    # *****************************************************

    def _remote_md5(self, conn, tmp, path):
        ''' takes a remote md5sum without requiring python, and returns 1 if no file '''

        path = pipes.quote(path)
        # The following test needs to be SH-compliant.  BASH-isms will
        # not work if /bin/sh points to a non-BASH shell.
        test = "rc=0; [ -r \"%s\" ] || rc=2; [ -f \"%s\" ] || rc=1; [ -d \"%s\" ] && rc=3" % ((path,) * 3)
        md5s = [
            "(/usr/bin/md5sum %s 2>/dev/null)" % path,  # Linux
            "(/sbin/md5sum -q %s 2>/dev/null)" % path,  # ?
            "(/usr/bin/digest -a md5 %s 2>/dev/null)" % path,   # Solaris 10+
            "(/sbin/md5 -q %s 2>/dev/null)" % path,     # Freebsd
            "(/usr/bin/md5 -n %s 2>/dev/null)" % path,  # Netbsd
            "(/bin/md5 -q %s 2>/dev/null)" % path,      # Openbsd
            "(/usr/bin/csum -h MD5 %s 2>/dev/null)" % path # AIX
        ]

        cmd = " || ".join(md5s)
        cmd = "%s; %s || (echo \"${rc}  %s\")" % (test, cmd, path)
        data = self._low_level_exec_command(conn, cmd, tmp, sudoable=True)
        data2 = utils.last_non_blank_line(data['stdout'])
        try:
            return data2.split()[0]
        except IndexError:
            sys.stderr.write("warning: md5sum command failed unusually, please report this to the list so it can be fixed\n")
            sys.stderr.write("command: %s\n" % md5s)
            sys.stderr.write("----\n")
            sys.stderr.write("output: %s\n" % data)
            sys.stderr.write("----\n")
            # this will signal that it changed and allow things to keep going
            return "INVALIDMD5SUM"

    # *****************************************************

    def _make_tmp_path(self, conn):
        ''' make and return a temporary path on a remote box '''

        basefile = 'ansible-tmp-%s-%s' % (time.time(), random.randint(0, 2**48))
        basetmp = os.path.join(C.DEFAULT_REMOTE_TMP, basefile)
        if (self.sudo or self.su) and (self.sudo_user != 'root' or self.su != 'root') and basetmp.startswith('$HOME'):
            basetmp = os.path.join('/tmp', basefile)

        cmd = 'mkdir -p %s' % basetmp
        if self.remote_user != 'root' or ((self.sudo or self.su) and (self.sudo_user != 'root' or self.su != 'root')):
            cmd += ' && chmod a+rx %s' % basetmp
        cmd += ' && echo %s' % basetmp

        result = self._low_level_exec_command(conn, cmd, None, sudoable=False)

        # error handling on this seems a little aggressive?
        if result['rc'] != 0:
            if result['rc'] == 5:
                output = 'Authentication failure.'
            elif result['rc'] == 255 and self.transport in ['ssh', 'ssh_old']:
                if utils.VERBOSITY > 3:
                    output = 'SSH encountered an unknown error. The output was:\n%s' % (result['stdout']+result['stderr'])
                else:
                    output = 'SSH encountered an unknown error during the connection. We recommend you re-run the command using -vvvv, which will enable SSH debugging output to help diagnose the issue'
            else:
                output = 'Authentication or permission failure.  In some cases, you may have been able to authenticate and did not have permissions on the remote directory. Consider changing the remote temp path in ansible.cfg to a path rooted in "/tmp". Failed command was: %s, exited with result %d' % (cmd, result['rc'])
            if 'stdout' in result and result['stdout'] != '':
                output = output + ": %s" % result['stdout']
            raise errors.AnsibleError(output)

        rc = utils.last_non_blank_line(result['stdout']).strip() + '/'
        # Catch failure conditions, files should never be
        # written to locations in /.
        if rc == '/': 
            raise errors.AnsibleError('failed to resolve remote temporary directory from %s: `%s` returned empty string' % (basetmp, cmd))
        return rc

    # *****************************************************

    def _remove_tmp_path(self, conn, tmp_path):
        ''' Remove a tmp_path. '''

        if "-tmp-" in tmp_path:
            cmd = "rm -rf %s >/dev/null 2>&1" % tmp_path
            self._low_level_exec_command(conn, cmd, None, sudoable=False)
            # If we have gotten here we have a working ssh configuration.
            # If ssh breaks we could leave tmp directories out on the remote system.

    # *****************************************************

    def _copy_module(self, conn, tmp, module_name, module_args, inject, complex_args=None):
        ''' transfer a module over SFTP, does not run it '''
        (
        module_style,
        module_shebang,
        module_data
        ) = self._configure_module(conn, module_name, module_args, inject, complex_args)
        module_remote_path = os.path.join(tmp, module_name)
        
        self._transfer_str(conn, tmp, module_name, module_data)
         
        return (module_remote_path, module_style, module_shebang)

    # *****************************************************

    def _configure_module(self, conn, module_name, module_args, inject, complex_args=None):
        ''' find module and configure it '''

        # Search module path(s) for named module.
        module_path = utils.plugins.module_finder.find_plugin(module_name)
        if module_path is None:
            raise errors.AnsibleFileNotFound("module %s not found in %s" % (module_name, utils.plugins.module_finder.print_paths()))


        # insert shared code and arguments into the module
        (module_data, module_style, module_shebang) = module_replacer.modify_module(
            module_path, complex_args, module_args, inject
        )

        return (module_style, module_shebang, module_data)


    # *****************************************************

    def _parallel_exec(self, hosts):
        ''' handles mulitprocessing when more than 1 fork is required '''

        FOON.set_size(self.forks)
        return FOON.map(_executor_hook, hosts)

    # *****************************************************

    def _partition_results(self, results):
        ''' separate results by ones we contacted & ones we didn't '''

        if results is None:
            return None
        results2 = dict(contacted={}, dark={})

        for result in results:
            host = result.host
            if host is None:
                raise Exception("internal error, host not set")
            if result.communicated_ok():
                results2["contacted"][host] = result.result
            else:
                results2["dark"][host] = result.result

        # hosts which were contacted but never got a chance to return
        for host in self.run_hosts:
            if not (host in results2['dark'] or host in results2['contacted']):
                results2["dark"][host] = {}
        return results2

    # *****************************************************

    def run(self):
        ''' xfer & run module on all matched hosts '''

        # find hosts that match the pattern
        if not self.run_hosts:
            self.run_hosts = self.inventory.list_hosts(self.pattern)
        hosts = self.run_hosts
        if len(hosts) == 0:
            self.callbacks.on_no_hosts()
            return dict(contacted={}, dark={})

        global multiprocessing_runner
        multiprocessing_runner = self
        results = None

        # Check if this is an action plugin. Some of them are designed
        # to be ran once per group of hosts. Example module: pause,
        # run once per hostgroup, rather than pausing once per each
        # host.
        p = utils.plugins.action_loader.get(self.module_name, self)

        if self.forks == 0 or self.forks > len(hosts):
            self.forks = len(hosts)

        if p and getattr(p, 'BYPASS_HOST_LOOP', None):

            # Expose the current hostgroup to the bypassing plugins
            self.host_set = hosts
            # We aren't iterating over all the hosts in this
            # group. So, just pick the first host in our group to
            # construct the conn object with.
            result_data = self._executor(hosts[0], None).result
            # Create a ResultData item for each host in this group
            # using the returned result. If we didn't do this we would
            # get false reports of dark hosts.
            results = [ ReturnData(host=h, result=result_data, comm_ok=True) \
                           for h in hosts ]
            del self.host_set

        elif self.forks > 1:
            try:
                results = self._parallel_exec(hosts)
            except IOError, ie:
                print ie.errno
                if ie.errno == 32:
                    # broken pipe from Ctrl+C
                    raise errors.AnsibleError("interrupted")
                raise
        else:
            results = [ self._executor(h, None) for h in hosts ]

        return self._partition_results(results)

    # *****************************************************

    def run_async(self, time_limit):
        ''' Run this module asynchronously and return a poller. '''

        self.background = time_limit
        results = self.run()
        return results, poller.AsyncPoller(results, self)

    # *****************************************************

    def noop_on_check(self, inject):
        ''' Should the runner run in check mode or not ? '''

        # initialize self.always_run on first call
        if self.always_run is None:
            self.always_run = self.module_vars.get('always_run', False)
            self.always_run = check_conditional(
                self.always_run, self.basedir, inject, fail_on_undefined=True)

        return (self.check and not self.always_run)