mitogen/ansible_mitogen/connection.py

# Copyright 2017, David Wilson
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# 1. Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
#
# 2. Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
#
# 3. Neither the name of the copyright holder nor the names of its contributors
# may be used to endorse or promote products derived from this software without
# specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.

from __future__ import absolute_import
from __future__ import unicode_literals

import logging
import os
import shlex
import stat
import time

import jinja2.runtime
import ansible.constants as C
import ansible.errors
import ansible.plugins.connection
import ansible.utils.shlex

import mitogen.unix
import mitogen.utils

import ansible_mitogen.parsing
import ansible_mitogen.process
import ansible_mitogen.services
import ansible_mitogen.target


LOG = logging.getLogger(__name__)


def _connect_local(spec):
    return {
        'method': 'local',
        'kwargs': {
            'python_path': spec['python_path'],
        }
    }


def wrap_or_none(klass, value):
    if value is not None:
        return klass(value)


def _connect_ssh(spec):
    if C.HOST_KEY_CHECKING:
        check_host_keys = 'enforce'
    else:
        check_host_keys = 'ignore'

    return {
        'method': 'ssh',
        'kwargs': {
            'check_host_keys': check_host_keys,
            'hostname': spec['remote_addr'],
            'username': spec['remote_user'],
            'password': wrap_or_none(mitogen.core.Secret, spec['password']),
            'port': spec['port'],
            'python_path': spec['python_path'],
            'identity_file': spec['private_key_file'],
            'ssh_path': spec['ssh_executable'],
            'connect_timeout': spec['ansible_ssh_timeout'],
            'ssh_args': spec['ssh_args'],
            'ssh_debug_level': spec['mitogen_ssh_debug_level'],
        }
    }


def _connect_docker(spec):
    return {
        'method': 'docker',
        'kwargs': {
            'username': spec['remote_user'],
            'container': spec['remote_addr'],
            'python_path': spec['python_path'],
            'connect_timeout': spec['ansible_ssh_timeout'] or spec['timeout'],
        }
    }


def _connect_jail(spec):
    return {
        'method': 'jail',
        'kwargs': {
            'username': spec['remote_user'],
            'container': spec['remote_addr'],
            'python_path': spec['python_path'],
            'connect_timeout': spec['ansible_ssh_timeout'] or spec['timeout'],
        }
    }


def _connect_lxc(spec):
    return {
        'method': 'lxc',
        'kwargs': {
            'container': spec['remote_addr'],
            'python_path': spec['python_path'],
            'connect_timeout': spec['ansible_ssh_timeout'] or spec['timeout'],
        }
    }


def _connect_machinectl(spec):
    return _connect_setns(dict(spec, mitogen_kind='machinectl'))


def _connect_setns(spec):
    return {
        'method': 'setns',
        'kwargs': {
            'container': spec['remote_addr'],
            'username': spec['remote_user'],
            'python_path': spec['python_path'],
            'kind': spec['mitogen_kind'],
            'docker_path': spec['mitogen_docker_path'],
            'lxc_info_path': spec['mitogen_lxc_info_path'],
            'machinectl_path': spec['mitogen_machinectl_path'],
        }
    }


def _connect_su(spec):
    return {
        'method': 'su',
        'enable_lru': True,
        'kwargs': {
            'username': spec['become_user'],
            'password': wrap_or_none(mitogen.core.Secret, spec['become_pass']),
            'python_path': spec['python_path'],
            'su_path': spec['become_exe'],
            'connect_timeout': spec['timeout'],
        }
    }


def _connect_sudo(spec):
    return {
        'method': 'sudo',
        'enable_lru': True,
        'kwargs': {
            'username': spec['become_user'],
            'password': wrap_or_none(mitogen.core.Secret, spec['become_pass']),
            'python_path': spec['python_path'],
            'sudo_path': spec['become_exe'],
            'connect_timeout': spec['timeout'],
            'sudo_args': spec['sudo_args'],
        }
    }


def _connect_doas(spec):
    return {
        'method': 'doas',
        'enable_lru': True,
        'kwargs': {
            'username': spec['become_user'],
            'password': wrap_or_none(mitogen.core.Secret, spec['become_pass']),
            'python_path': spec['python_path'],
            'doas_path': spec['become_exe'],
            'connect_timeout': spec['timeout'],
        }
    }


def _connect_mitogen_su(spec):
    # su as a first-class proxied connection, not a become method.
    return {
        'method': 'su',
        'kwargs': {
            'username': spec['remote_user'],
            'password': wrap_or_none(mitogen.core.Secret, spec['password']),
            'python_path': spec['python_path'],
            'su_path': spec['become_exe'],
            'connect_timeout': spec['timeout'],
        }
    }


def _connect_mitogen_sudo(spec):
    # sudo as a first-class proxied connection, not a become method.
    return {
        'method': 'sudo',
        'kwargs': {
            'username': spec['remote_user'],
            'password': wrap_or_none(mitogen.core.Secret, spec['password']),
            'python_path': spec['python_path'],
            'sudo_path': spec['become_exe'],
            'connect_timeout': spec['timeout'],
            'sudo_args': spec['sudo_args'],
        }
    }


def _connect_mitogen_doas(spec):
    # doas as a first-class proxied connection, not a become method.
    return {
        'method': 'doas',
        'kwargs': {
            'username': spec['remote_user'],
            'password': wrap_or_none(mitogen.core.Secret, spec['password']),
            'python_path': spec['python_path'],
            'doas_path': spec['become_exe'],
            'connect_timeout': spec['timeout'],
        }
    }


CONNECTION_METHOD = {
    'docker': _connect_docker,
    'jail': _connect_jail,
    'local': _connect_local,
    'lxc': _connect_lxc,
    'lxd': _connect_lxc,
    'machinectl': _connect_machinectl,
    'setns': _connect_setns,
    'ssh': _connect_ssh,
    'su': _connect_su,
    'sudo': _connect_sudo,
    'doas': _connect_doas,
    'mitogen_su': _connect_mitogen_su,
    'mitogen_sudo': _connect_mitogen_sudo,
    'mitogen_doas': _connect_mitogen_doas,
}


def parse_python_path(s):
    """
    Given the string set for ansible_python_interpeter, parse it using shell
    syntax and return an appropriate argument vector.
    """
    if not s:
        return None

    return shlex.split(s)


def config_from_play_context(transport, inventory_name, connection):
    """
    Return a dict representing all important connection configuration, allowing
    the same functions to work regardless of whether configuration came from
    play_context (direct connection) or host vars (mitogen_via=).
    """
    return {
        'transport': transport,
        'inventory_name': inventory_name,
        'remote_addr': connection._play_context.remote_addr,
        'remote_user': connection._play_context.remote_user,
        'become': connection._play_context.become,
        'become_method': connection._play_context.become_method,
        'become_user': connection._play_context.become_user,
        'become_pass': connection._play_context.become_pass,
        'password': connection._play_context.password,
        'port': connection._play_context.port,
        'python_path': parse_python_path(connection.python_path),
        'private_key_file': connection._play_context.private_key_file,
        'ssh_executable': connection._play_context.ssh_executable,
        'timeout': connection._play_context.timeout,
        'ansible_ssh_timeout': connection.ansible_ssh_timeout,
        'ssh_args': [
            mitogen.core.to_text(term)
            for s in (
                getattr(connection._play_context, 'ssh_args', ''),
                getattr(connection._play_context, 'ssh_common_args', ''),
                getattr(connection._play_context, 'ssh_extra_args', '')
            )
            for term in ansible.utils.shlex.shlex_split(s or '')
        ],
        'become_exe': connection._play_context.become_exe,
        'sudo_args': [
            mitogen.core.to_text(term)
            for s in (
                connection._play_context.sudo_flags,
                connection._play_context.become_flags
            )
            for term in ansible.utils.shlex.shlex_split(s or '')
        ],
        'mitogen_via': connection.mitogen_via,
        'mitogen_kind': connection.mitogen_kind,
        'mitogen_docker_path': connection.mitogen_docker_path,
        'mitogen_lxc_info_path': connection.mitogen_lxc_info_path,
        'mitogen_machinectl_path': connection.mitogen_machinectl_path,
        'mitogen_ssh_debug_level': connection.mitogen_ssh_debug_level,
    }


def config_from_hostvars(transport, inventory_name, connection,
                         hostvars, become_user):
    """
    Override config_from_play_context() to take equivalent information from
    host vars.
    """
    config = config_from_play_context(transport, inventory_name, connection)
    hostvars = dict(hostvars)
    return dict(config, **{
        'remote_addr': hostvars.get('ansible_hostname', inventory_name),
        'become': bool(become_user),
        'become_user': become_user,
        'become_pass': None,
        'remote_user': hostvars.get('ansible_user'),  # TODO
        'password': (hostvars.get('ansible_ssh_pass') or
                     hostvars.get('ansible_password')),
        'port': hostvars.get('ansible_port'),
        'python_path': parse_python_path(hostvars.get('ansible_python_interpreter')),
        'private_key_file': (hostvars.get('ansible_ssh_private_key_file') or
                             hostvars.get('ansible_private_key_file')),
        'mitogen_via': hostvars.get('mitogen_via'),
        'mitogen_kind': hostvars.get('mitogen_kind'),
        'mitogen_docker_path': hostvars.get('mitogen_docker_path'),
        'mitogen_lxc_info_path': hostvars.get('mitogen_lxc_info_path'),
        'mitogen_machinectl_path': hostvars.get('mitogen_machinctl_path'),
    })


class Connection(ansible.plugins.connection.ConnectionBase):
    #: mitogen.master.Broker for this worker.
    broker = None

    #: mitogen.master.Router for this worker.
    router = None

    #: mitogen.parent.Context representing the parent Context, which is
    #: presently always the connection multiplexer process.
    parent = None

    #: mitogen.parent.Context for the target account on the target, possibly
    #: reached via become.
    context = None

    #: mitogen.parent.Context for the login account on the target. This is
    #: always the login account, even when become=True.
    login_context = None

    #: mitogen.parent.Context connected to the fork parent process in the
    #: target user account.
    fork_context = None

    #: Only sudo, su, and doas are supported for now.
    become_methods = ['sudo', 'su', 'doas']

    #: Set to 'ansible_python_interpreter' by on_action_run().
    python_path = None

    #: Set to 'ansible_ssh_timeout' by on_action_run().
    ansible_ssh_timeout = None

    #: Set to 'mitogen_via' by on_action_run().
    mitogen_via = None

    #: Set to 'mitogen_kind' by on_action_run().
    mitogen_kind = None

    #: Set to 'mitogen_docker_path' by on_action_run().
    mitogen_docker_path = None

    #: Set to 'mitogen_lxc_info_path' by on_action_run().
    mitogen_lxc_info_path = None

    #: Set to 'mitogen_lxc_info_path' by on_action_run().
    mitogen_machinectl_path = None

    #: Set to 'mitogen_ssh_debug_level' by on_action_run().
    mitogen_ssh_debug_level = None

    #: Set to 'inventory_hostname' by on_action_run().
    inventory_hostname = None

    #: Set to 'hostvars' by on_action_run()
    host_vars = None

    #: Set to '_loader.get_basedir()' by on_action_run().
    loader_basedir = None

    #: Set after connection to the target context's home directory.
    home_dir = None

    def __init__(self, play_context, new_stdin, **kwargs):
        assert ansible_mitogen.process.MuxProcess.unix_listener_path, (
            'Mitogen connection types may only be instantiated '
            'while the "mitogen" strategy is active.'
        )
        super(Connection, self).__init__(play_context, new_stdin)

    def __del__(self):
        """
        Ansible cannot be trusted to always call close() e.g. the synchronize
        action constructs a local connection like this. So provide a destructor
        in the hopes of catching these cases.
        """
        # https://github.com/dw/mitogen/issues/140
        self.close()

    def on_action_run(self, task_vars, loader_basedir):
        """
        Invoked by ActionModuleMixin to indicate a new task is about to start
        executing. We use the opportunity to grab relevant bits from the
        task-specific data.
        """
        self.ansible_ssh_timeout = task_vars.get('ansible_ssh_timeout',
                                                 C.DEFAULT_TIMEOUT)
        self.python_path = task_vars.get('ansible_python_interpreter',
                                         '/usr/bin/python')
        self.mitogen_via = task_vars.get('mitogen_via')
        self.mitogen_kind = task_vars.get('mitogen_kind')
        self.mitogen_docker_path = task_vars.get('mitogen_docker_path')
        self.mitogen_lxc_info_path = task_vars.get('mitogen_lxc_info_path')
        self.mitogen_machinectl_path = task_vars.get('mitogen_machinectl_path')
        self.mitogen_ssh_debug_level = task_vars.get('mitogen_ssh_debug_level')
        self.inventory_hostname = task_vars['inventory_hostname']
        self.host_vars = task_vars['hostvars']
        self.loader_basedir = loader_basedir
        self.close(new_task=True)

    @property
    def homedir(self):
        self._connect()
        return self.home_dir

    @property
    def connected(self):
        return self.context is not None

    def _config_from_via(self, via_spec):
        become_user, _, inventory_name = via_spec.rpartition('@')
        via_vars = self.host_vars[inventory_name]
        if isinstance(via_vars, jinja2.runtime.Undefined):
            raise ansible.errors.AnsibleConnectionFailure(
                self.unknown_via_msg % (
                    self.mitogen_via,
                    inventory_name,
                )
            )

        return config_from_hostvars(
            transport=via_vars.get('ansible_connection', 'ssh'),
            inventory_name=inventory_name,
            connection=self,
            hostvars=via_vars,
            become_user=become_user or None,
        )

    unknown_via_msg = 'mitogen_via=%s of %s specifies an unknown hostname'
    via_cycle_msg = 'mitogen_via=%s of %s creates a cycle (%s)'

    def _stack_from_config(self, config, stack=(), seen_names=()):
        if config['inventory_name'] in seen_names:
            raise ansible.errors.AnsibleConnectionFailure(
                self.via_cycle_msg % (
                    config['mitogen_via'],
                    config['inventory_name'],
                    ' -> '.join(reversed(
                        seen_names + (config['inventory_name'],)
                    )),
                )
            )

        if config['mitogen_via']:
            stack, seen_names = self._stack_from_config(
                self._config_from_via(config['mitogen_via']),
                stack=stack,
                seen_names=seen_names + (config['inventory_name'],)
            )

        stack += (CONNECTION_METHOD[config['transport']](config),)
        if config['become']:
            stack += (CONNECTION_METHOD[config['become_method']](config),)

        return stack, seen_names

    def _connect(self):
        """
        Establish a connection to the master process's UNIX listener socket,
        constructing a mitogen.master.Router to communicate with the master,
        and a mitogen.parent.Context to represent it.

        Depending on the original transport we should emulate, trigger one of
        the _connect_*() service calls defined above to cause the master
        process to establish the real connection on our behalf, or return a
        reference to the existing one.
        """
        if self.connected:
            return

        if not self.broker:
            self.broker = mitogen.master.Broker()
            self.router, self.parent = mitogen.unix.connect(
                path=ansible_mitogen.process.MuxProcess.unix_listener_path,
                broker=self.broker,
            )

        stack, _ = self._stack_from_config(
            config_from_play_context(
                transport=self.transport,
                inventory_name=self.inventory_hostname,
                connection=self
            )
        )

        dct = self.parent.call_service(
            service_name='ansible_mitogen.services.ContextService',
            method_name='get',
            stack=mitogen.utils.cast(list(stack)),
        )

        if dct['msg']:
            if dct['method_name'] in self.become_methods:
                raise ansible.errors.AnsibleModuleError(dct['msg'])
            raise ansible.errors.AnsibleConnectionFailure(dct['msg'])

        self.context = dct['context']
        if self._play_context.become:
            self.login_context = dct['via']
        else:
            self.login_context = self.context

        self.fork_context = dct['init_child_result']['fork_context']
        self.home_dir = dct['init_child_result']['home_dir']

    def close(self, new_task=False):
        """
        Arrange for the mitogen.master.Router running in the worker to
        gracefully shut down, and wait for shutdown to complete. Safe to call
        multiple times.
        """
        if self.context:
            self.parent.call_service(
                service_name='ansible_mitogen.services.ContextService',
                method_name='put',
                context=self.context
            )

        self.context = None
        self.fork_context = None
        self.login_context = None
        if self.broker and not new_task:
            self.broker.shutdown()
            self.broker.join()
            self.broker = None
            self.router = None

    def call_async(self, func, *args, **kwargs):
        """
        Start a function call to the target.

        :param bool use_login_context:
            If present and :data:`True`, send the call to the login account
            context rather than the optional become user context.
        :returns:
            mitogen.core.Receiver that receives the function call result.
        """
        self._connect()
        if kwargs.pop('use_login_context', None):
            call_context = self.login_context
        else:
            call_context = self.context
        return call_context.call_async(func, *args, **kwargs)

    def call(self, func, *args, **kwargs):
        """
        Start and wait for completion of a function call in the target.

        :raises mitogen.core.CallError:
            The function call failed.
        :returns:
            Function return value.
        """
        t0 = time.time()
        try:
            return self.call_async(func, *args, **kwargs).get().unpickle()
        finally:
            LOG.debug('Call took %d ms: %s%r', 1000 * (time.time() - t0),
                      func.__name__, args)

    def create_fork_child(self):
        """
        Fork a new child off the target context. The actual fork occurs from
        the 'virginal fork parent', which does not any Ansible modules prior to
        fork, to avoid conflicts resulting from custom module_utils paths.

        :returns:
            mitogen.core.Context of the new child.
        """
        return self.call(ansible_mitogen.target.create_fork_child)

    def get_default_cwd(self):
        """
        Overridden by connections/mitogen_local.py to emulate behaviour of CWD
        being fixed to that of ActionBase._loader.get_basedir().
        """
        return None

    def get_default_env(self):
        """
        Overridden by connections/mitogen_local.py to emulate behaviour of
        WorkProcess environment inherited from WorkerProcess.
        """
        return None

    def exec_command(self, cmd, in_data='', sudoable=True, mitogen_chdir=None):
        """
        Implement exec_command() by calling the corresponding
        ansible_mitogen.target function in the target.

        :param str cmd:
            Shell command to execute.
        :param bytes in_data:
            Data to supply on ``stdin`` of the process.
        :returns:
            (return code, stdout bytes, stderr bytes)
        """
        emulate_tty = (not in_data and sudoable)
        rc, stdout, stderr = self.call(
            ansible_mitogen.target.exec_command,
            cmd=mitogen.utils.cast(cmd),
            in_data=mitogen.utils.cast(in_data),
            chdir=mitogen_chdir or self.get_default_cwd(),
            emulate_tty=emulate_tty,
        )

        stderr += 'Shared connection to %s closed.%s' % (
            self._play_context.remote_addr,
            ('\r\n' if emulate_tty else '\n'),
        )
        return rc, stdout, stderr

    def fetch_file(self, in_path, out_path):
        """
        Implement fetch_file() by calling the corresponding
        ansible_mitogen.target function in the target.

        :param str in_path:
            Remote filesystem path to read.
        :param str out_path:
            Local filesystem path to write.
        """
        output = self.call(ansible_mitogen.target.read_path,
                           mitogen.utils.cast(in_path))
        ansible_mitogen.target.write_path(out_path, output)

    def put_data(self, out_path, data, mode=None, utimes=None):
        """
        Implement put_file() by caling the corresponding
        ansible_mitogen.target function in the target.

        :param str out_path:
            Remote filesystem path to write.
        :param byte data:
            File contents to put.
        """
        self.call(ansible_mitogen.target.write_path,
                  mitogen.utils.cast(out_path),
                  mitogen.core.Blob(data),
                  mode=mode,
                  utimes=utimes)

    def put_file(self, in_path, out_path):
        """
        Implement put_file() by streamily transferring the file via
        FileService.

        :param str in_path:
            Local filesystem path to read.
        :param str out_path:
            Remote filesystem path to write.
        """
        st = os.stat(in_path)
        if not stat.S_ISREG(st.st_mode):
            raise IOError('%r is not a regular file.' % (in_path,))

        # If the file is sufficiently small, just ship it in the argument list
        # rather than introducing an extra RTT for the child to request it from
        # FileService.
        if st.st_size <= 32768:
            fp = open(in_path, 'rb')
            try:
                s = fp.read(32769)
            finally:
                fp.close()

            # Ensure file was not growing during call.
            if len(s) == st.st_size:
                return self.put_data(out_path, s, mode=st.st_mode,
                                     utimes=(st.st_atime, st.st_mtime))

        self.parent.call_service(
            service_name='mitogen.service.FileService',
            method_name='register',
            path=mitogen.utils.cast(in_path)
        )
        self.call(
            ansible_mitogen.target.transfer_file,
            context=self.parent,
            in_path=in_path,
            out_path=out_path
        )