openstack-ansible/playbooks/library/lxc-container

#!/usr/bin/python
# (c) 2014, Kevin Carter <kevin.carter@rackspace.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/>.


# This module has been PR'd against upstream ansible. Please review the module
# here: https://github.com/ansible/ansible-modules-extras/pull/123


DOCUMENTATION = """
---
module: lxc-container
short_description: Manage LXC Containers
version_added: 1.8.0
description:
  - Management of LXC containers
author: Kevin Carter
options:
    name:
        description:
          - Name of a container.
        required: true
    backing_store:
        choices:
          - dir
          - lvm
          - loop
          - btrfs
        description:
          - Backend storage type for the container.
        required: false
        default: dir
    template:
        description:
          - Name of the template to use within an LXC create.
        required: false
        default: ubuntu
    template_options:
        description:
          - Template options when building the container.
        required: false
    config:
        description:
          - Path to the LXC configuration file.
        required: false
        default: /etc/lxc/default.conf
    lv_name:
        description:
          - Name of the logical volume, defaults to the container name.
        default: $CONTAINER_NAME
        required: false
    vg_name:
        description:
          - If Backend store is lvm, specify the name of the volume group.
        default: lxc
        required: false
    thinpool:
        description:
          - Use LVM thin pool called TP.
        required: false
    fs_type:
        description:
          - Create fstype TYPE.
        default: ext4
        required: false
    fs_size:
        description:
          - File system Size.
        default: 5G
        required: false
    directory:
        description:
          - Place rootfs directory under DIR.
        required: false
    zfs_root:
        description:
          - Create zfs under given zfsroot.
        required: false
    container_command:
        description:
          - Run a command within a container.
        required: false
    lxc_path:
        description:
          - Place container under PATH
        required: false
    container_log:
        choices:
          - true
          - false
        description:
          - Enable a container log for host actions to the container.
        default: false
    container_log_level:
        choices:
          - INFO
          - ERROR
          - DEBUG
        description:
          - Set the log level for a container where *container_log* was set.
        required: false
        default: INFO
    archive:
        choices:
          - true
          - false
        description:
          - Create an archive of a container. This will create a tarball of the
            running container.
        default: false
    archive_path:
        description:
          - Path the save the archived container. If the path does not exist
            the archive method will attempt to create it.
        default: /tmp
    archive_compression:
        choices:
          - gzip
          - bzip2
          - none
        description:
          - Type of compression to use when creating an archive of a running
            container.
        default: gzip
    state:
        choices:
          - started
          - stopped
          - restarted
          - absent
          - frozen
        description:
          - Start a container right after it's created.
        required: false
        default: started
    container_config:
        description:
          - list of 'key=value' options to use when configuring a container.
        required: false
requirements: ['lxc >= 1.0', 'python2-lxc >= 0.1']
notes:
  - Containers must have a unique name. If you attempt to create a container
    with a name that already exists in the users namespace the module will
    simply return as "unchanged".
  - The "container_command" can be used with any state except "absent". If
    used with state "stopped" the container will be "started", the command
    executed, and then the container "stopped" again. Likewise if the state
    is "stopped" and the container does not exist it will be first created,
    "started", the command executed, and then "stopped". If you use a "|"
    in the variable you can use common script formatting within the variable
    iteself The "container_command" option will always execute as BASH.
    When using "container_command" a log file is created in the /tmp/ directory
    which contains both stdout and stderr of any command executed.
  - If "archive" is **true** the system will attempt to create a compressed
    tarball of the running container. The "archive" option supports LVM backed
    containers and will create a snapshot of the running container when
    creating the archive.
  - If your distro does not have a package for "python2-lxc", which is a
    requirement for this module, it can be installed from source at
    "https://github.com/lxc/python2-lxc"
"""

EXAMPLES = """
- name: Create a started container
  lxc-container:
    name: test-container-started
    container_log: true
    template: ubuntu
    state: started
    template_options: --release trusty

- name: Create a stopped container
  lxc-container:
    name: test-container-stopped
    container_log: true
    template: ubuntu
    state: stopped
    template_options: --release trusty

- name: Create a frozen container
  lxc-container:
    name: test-container-frozen
    container_log: true
    template: ubuntu
    state: frozen
    template_options: --release trusty
    container_command: |
      echo 'hello world.' | tee /opt/started-frozen

# Create filesystem container, configure it, and archive it, and start it.
- name: Create filesystem container
  lxc-container:
    name: test-container-config
    container_log: true
    template: ubuntu
    state: started
    archive: true
    archive_compression: none
    container_config:
      - "lxc.aa_profile=unconfined"
      - "lxc.cgroup.devices.allow=a *:* rmw"
    template_options: --release trusty

# Create an lvm container, run a complex command in it, add additional
# configuration to it, create an archive of it, and finally leave the container
# in a frozen state. The container archive will be compressed using bzip2
- name: Create an lvm container
  lxc-container:
    name: test-container-lvm
    container_log: true
    template: ubuntu
    state: frozen
    backing_store: lvm
    template_options: --release trusty
    container_command: |
      apt-get update
      apt-get install -y vim lxc-dev
      echo 'hello world.' | tee /opt/started
      if [[ -f "/opt/started" ]]; then
          echo 'hello world.' | tee /opt/found-started
      fi
    container_config:
      - "lxc.aa_profile=unconfined"
      - "lxc.cgroup.devices.allow=a *:* rmw"
    archive: true
    archive_compression: bzip2
  register: lvm_container_info

- name: Debug info on container "test-container-lvm"
  debug: var=lvm_container_info

- name: Get information on a given container.
  lxc-container:
    name: test-container-config
  register: config_container_info

- name: debug info on container "test-container"
  debug: var=config_container_info

- name: Run a command in a container and ensure its in a "stopped" state.
  lxc-container:
    name: test-container-started
    state: stopped
    container_command: |
      echo 'hello world.' | tee /opt/stopped

- name: Run a command in a container and ensure its it in a "frozen" state.
  lxc-container:
    name: test-container-stopped
    state: frozen
    container_command: |
      echo 'hello world.' | tee /opt/frozen

- name: Start a container.
  lxc-container:
    name: test-container-stopped
    state: started

- name: Run a command in a container and then restart it.
  lxc-container:
    name: test-container-started
    state: restarted
    container_command: |
      echo 'hello world.' | tee /opt/restarted

- name: Run a complex command within a "running" container.
  lxc-container:
    name: test-container-started
    container_command: |
      apt-get update
      apt-get install -y curl wget vim apache2
      echo 'hello world.' | tee /opt/started
      if [[ -f "/opt/started" ]]; then
          echo 'hello world.' | tee /opt/found-started
      fi

# Create an archive of an existing container, save the archive to a defined
# path and then destroy it.
- name: Archive container
  lxc-container:
    name: test-container-started
    state: absent
    archive: true
    archive_path: /opt/archives

- name: Destroy a container.
  lxc-container:
    name: "{{ item }}"
    state: absent
  with_items:
    - test-container-stopped
    - test-container-started
    - test-container-frozen
    - test-container-lvm
    - test-container-config
"""


try:
    import lxc
except ImportError:
    msg = 'The lxc module is not importable. Check the requirements.'
    print("failed=True msg='%s'" % msg)
    raise SystemExit(msg)


# LXC_COMPRESSION_MAP is a map of available compression types when creating
# an archive of a container.
LXC_COMPRESSION_MAP = {
    'gzip': {
        'extension': 'tar.tgz',
        'argument': '-czf'
    },
    'bzip2': {
        'extension': 'tar.bz2',
        'argument': '-cjf'
    },
    'none': {
        'extension': 'tar',
        'argument': '-cf'
    }
}


# LXC_COMMAND_MAP is a map of variables that are available to a method based
# on the state the container is in.
LXC_COMMAND_MAP = {
    'create': {
        'variables': {
            'config': '--config',
            'template': '--template',
            'backing_store': '--bdev',
            'lxc_path': '--lxcpath',
            'lv_name': '--lvname',
            'vg_name': '--vgname',
            'thinpool': '--thinpool',
            'fs_type': '--fstype',
            'fs_size': '--fssize',
            'directory': '--dir',
            'zfs_root': '--zfsroot'
        }
    }
}


# LXC_BACKING_STORE is a map of available storage backends and options that
# are incompatible with the given storage backend.
LXC_BACKING_STORE = {
    'dir': [
        'lv_name', 'vg_name', 'fs_type', 'fs_size', 'thinpool'
    ],
    'lvm': [
        'zfs_root'
    ],
    'btrfs': [
        'lv_name', 'vg_name', 'thinpool', 'zfs_root'
    ],
    'loop': [
        'lv_name', 'vg_name', 'thinpool', 'zfs_root'
    ]
}


# LXC_LOGGING_LEVELS is a map of available log levels
LXC_LOGGING_LEVELS = {
    'INFO': ['info', 'INFO', 'Info'],
    'ERROR': ['error', 'ERROR', 'Error'],
    'DEBUG': ['debug', 'DEBUG', 'Debug']
}


# LXC_ANSIBLE_STATES is a map of states that contain values of methods used
# when a particular state is evoked.
LXC_ANSIBLE_STATES = {
    'started': '_started',
    'stopped': '_stopped',
    'restarted': '_restarted',
    'absent': '_destroyed',
    'frozen': '_frozen'
}


# This is used to attach to a running container and execute commands from
# within the container on the host.  This will provide local access to a
# container without using SSH.  The template will attempt to work within the
# home directory of the user that was attached to the container and source
# that users environment variables by default.
ATTACH_TEMPLATE = """#!/usr/bin/env bash
pushd "$(grep $(whoami) /etc/passwd | awk -F':' '{print $6}')"
    if [[ -f ".bashrc" ]];then
        source .bashrc
    fi
popd

# User defined command
%(container_command)s
"""


def create_script(command):
    """Write out a script onto a target.

    This method should be backward compatible with Python 2.4+ when executing
    from within the container.

    :param command: command to run, this can be a script and can use spacing
                    with newlines as separation.
    :type command: ``str``
    """

    import os
    import os.path as path
    import subprocess
    import tempfile

    # Ensure that the directory /opt exists.
    if not path.isdir('/opt'):
        os.mkdir('/opt')

    # Create the script.
    script_file = path.join('/opt', '.lxc-attach-script')
    f = open(script_file, 'wb')
    try:
        f.write(ATTACH_TEMPLATE % {'container_command': command})
        f.flush()
    finally:
        f.close()

    # Ensure the script is executable.
    os.chmod(script_file, 0755)

    # Get temporary directory.
    tempdir = tempfile.gettempdir()

    # Output log file.
    stdout = path.join(tempdir, 'lxc-attach-script.log')
    stdout_file = open(stdout, 'ab')

    # Error log file.
    stderr = path.join(tempdir, 'lxc-attach-script.err')
    stderr_file = open(stderr, 'ab')

    # Execute the script command.
    try:
        subprocess.Popen(
            [script_file],
            stdout=stdout_file,
            stderr=stderr_file
        ).communicate()
    finally:
        # Close the log files.
        stderr_file.close()
        stdout_file.close()

        # Remove the script file upon completion of execution.
        os.remove(script_file)


class LxcContainerManagement(object):
    def __init__(self, module):
        """Management of LXC containers via Ansible.

        :param module: Processed Ansible Module.
        :type module: ``object``
        """
        self.module = module
        self.state = self.module.params.get('state', None)
        self.state_change = False
        self.lxc_vg = None
        self.container_name = self.module.params['name']
        self.container = self.get_container_bind()
        self.archive_info = None

    def get_container_bind(self):
        return lxc.Container(name=self.container_name)

    @staticmethod
    def _roundup(num):
        """Return a rounded floating point number.

        :param num: Number to round up.
        :type: ``float``
        :returns: Rounded up number.
        :rtype: ``int``
        """
        num, part = str(num).split('.')
        num = int(num)
        if int(part) != 0:
            num += 1
        return num

    @staticmethod
    def _container_exists(name):
        """Check if a container exists.

        :param name: Name of the container.
        :type: ``str``
        :returns: True or False if the container is found.
        :rtype: ``bol``
        """
        if [i for i in lxc.list_containers() if i == name]:
            return True
        else:
            return False

    @staticmethod
    def _add_variables(variables_dict, build_command):
        """Return a command list with all found options.

        :param variables_dict: Pre-parsed optional variables used from a
                               seed command.
        :type variables_dict: ``dict``
        :param build_command: Command to run.
        :type build_command: ``list``
        :returns: list of command options.
        :rtype: ``list``
        """

        for key, value in variables_dict.items():
            build_command.append(
                '%s %s' % (key, value)
            )
        else:
            return build_command

    def _get_vars(self, variables):
        """Return a dict of all variables as found within the module.

        :param variables: Hash of all variables to find.
        :type variables: ``dict``
        """

        # Remove incompatible storage backend options.
        for v in LXC_BACKING_STORE[self.module.params['backing_store']]:
            variables.pop(v, None)

        return_dict = dict()
        for k, v in variables.items():
            _var = self.module.params.get(k)
            if not [i for i in [None, ''] + BOOLEANS_FALSE if i == _var]:
                return_dict[v] = _var
        else:
            return return_dict

    def _run_command(self, build_command, unsafe_shell=False, timeout=600):
        """Return information from running an Ansible Command.

        This will squash the build command list into a string and then
        execute the command via Ansible. The output is returned to the method.
        This output is returned as `return_code`, `stdout`, `stderr`.

        Prior to running the command the method will look to see if the LXC
        lockfile is present. If the lockfile "/var/lock/subsys/lxc" the method
        will wait upto 10 minutes for it to be gone; polling every 5 seconds.

        :param build_command: Used for the command and all options.
        :type build_command: ``list``
        :param unsafe_shell: Enable or Disable unsafe sell commands.
        :type unsafe_shell: ``bol``
        :param timeout: Time before the container create process quites.
        :type timeout: ``int``
        """

        lockfile = '/var/lock/subsys/lxc'

        for _ in xrange(timeout):
            if os.path.exists(lockfile):
                time.sleep(1)
            else:
                return self.module.run_command(
                    ' '.join(build_command),
                    use_unsafe_shell=unsafe_shell
                )
        else:
            message = (
                'The LXC subsystem is locked and after 5 minutes it never'
                ' became unlocked. Lockfile [ %s ]' % lockfile
            )
            self.failure(
                error='LXC subsystem locked',
                rc=0,
                msg=message
            )

    def _config(self):
        """Configure an LXC container.

        Write new configuration values to the lxc config file. This will
        stop the container if it's running write the new options and then
        restart the container upon completion.
        """

        _container_config = self.module.params.get('container_config')
        if not _container_config:
            return False

        container_config_file = self.container.config_file_name
        with open(container_config_file, 'rb') as f:
            container_config = f.readlines()

        # Note used ast literal_eval because AnsibleModule does not provide for
        # adequate dictionary parsing.
        # Issue: https://github.com/ansible/ansible/issues/7679
        # TODO(cloudnull) adjust import when issue has been resolved.
        import ast
        options_dict = ast.literal_eval(_container_config)
        parsed_options = [i.split('=') for i in options_dict]

        config_change = False
        for key, value in parsed_options:
            new_entry = '%s = %s\n' % (key, value)
            for option_line in container_config:
                # Look for key in config
                if option_line.startswith(key):
                    _, _value = option_line.split('=')
                    config_value = ' '.join(_value.split())
                    line_index = container_config.index(option_line)
                    # If the sanitized values don't match replace them
                    if value != config_value:
                        line_index += 1
                        if new_entry not in container_config:
                            config_change = True
                            container_config.insert(line_index, new_entry)
                    # Break the flow as values are written or not at this point
                    break
            else:
                config_change = True
                container_config.append(new_entry)

        # If the config changed restart the container.
        if config_change:
            container_state = self._get_state()
            if container_state != 'stopped':
                self.container.stop()

            with open(container_config_file, 'wb') as f:
                f.writelines(container_config)

            self.state_change = True
            if container_state == 'running':
                self._container_startup()
            elif container_state == 'frozen':
                self._container_startup()
                self.container.freeze()

    def _create(self):
        """Create a new LXC container.

        This method will build and execute a shell command to build the
        container. It would have been nice to simply use the lxc python library
        however at the time this was written the python library, in both py2
        and py3 didn't support some of the more advanced container create
        processes. These missing processes mainly revolve around backing
        LXC containers with block devices.
        """

        build_command = [
            self.module.get_bin_path('lxc-create', True),
            '--name %s' % self.container_name,
            '--quiet'
        ]

        build_command = self._add_variables(
            variables_dict=self._get_vars(
                variables=LXC_COMMAND_MAP['create']['variables']
            ),
            build_command=build_command
        )

        # Load logging for the instance when creating it.
        if self.module.params.get('container_log') in BOOLEANS_TRUE:
            # Set the logging path to the /var/log/lxc if uid is root. else
            # set it to the home folder of the user executing.
            try:
                if os.getuid() != 0:
                    log_path = os.getenv('HOME')
                else:
                    if not os.path.isdir('/var/log/lxc/'):
                        os.makedirs('/var/log/lxc/')
                    log_path = '/var/log/lxc/'
            except OSError:
                log_path = os.getenv('HOME')

            build_command.extend([
                '--logfile %s' % os.path.join(
                    log_path, 'lxc-%s.log' % self.container_name
                ),
                '--logpriority %s' % self.module.params.get(
                    'container_log_level'
                ).upper()
            ])

        # Add the template commands to the end of the command if there are any
        template_options = self.module.params.get('template_options', None)
        if template_options:
            build_command.append('-- %s' % template_options)

        rc, return_data, err = self._run_command(build_command)
        if rc != 0:
            msg = "Failed executing lxc-create."
            self.failure(
                err=err, rc=rc, msg=msg, command=' '.join(build_command)
            )
        else:
            self.state_change = True

    def _container_data(self):
        """Returns a dict of container information.

        :returns: container data
        :rtype: ``dict``
        """

        return {
            'interfaces': self.container.get_interfaces(),
            'ips': self.container.get_ips(),
            'state': self._get_state(),
            'init_pid': int(self.container.init_pid)
        }

    def _unfreeze(self):
        """Unfreeze a container.

        :returns: True or False based on if the container was unfrozen.
        :rtype: ``bol``
        """

        unfreeze = self.container.unfreeze()
        if unfreeze:
            self.state_change = True
        return unfreeze

    def _get_state(self):
        """Return the state of a container.

        If the container is not found the state returned is "absent"

        :returns: state of a container as a lower case string.
        :rtype: ``str``
        """

        if self._container_exists(name=self.container_name):
            return str(self.container.state).lower()
        else:
            return str('absent')

    def _execute_command(self):
        """Execute a shell command."""

        container_command = self.module.params.get('container_command')
        if container_command:
            container_state = self._get_state()
            if container_state == 'frozen':
                self._unfreeze()
            elif container_state == 'stopped':
                self._container_startup()

            self.container.attach_wait(create_script, container_command)
            self.state_change = True

    def _container_startup(self, timeout=60):
        """Ensure a container is started.

        :param timeout: Time before the destroy operation is abandoned.
        :type timeout: ``int``
        """

        self.container = self.get_container_bind()
        for _ in xrange(timeout):
            if self._get_state() != 'running':
                self.container.start()
                self.state_change = True
                # post startup sleep for 1 second.
                time.sleep(1)
            else:
                return True
        else:
            self.failure(
                lxc_container=self._container_data(),
                error='Failed to start container'
                      ' [ %s ]' % self.container_name,
                rc=1,
                msg='The container [ %s ] failed to start. Check to lxc is'
                    ' available and that the container is in a functional'
                    ' state.'
            )

    def _check_archive(self):
        """Create a compressed archive of a container.

        This will store archive_info in as self.archive_info
        """

        if self.module.params.get('archive') in BOOLEANS_TRUE:
            self.archive_info = {
                'archive': self._container_create_tar()
            }

    def _destroyed(self, timeout=60):
        """Ensure a container is destroyed.

        :param timeout: Time before the destroy operation is abandoned.
        :type timeout: ``int``
        """

        for _ in xrange(timeout):
            if not self._container_exists(name=self.container_name):
                break

            # Check if the container needs to have an archive created.
            self._check_archive()

            if self._get_state() != 'stopped':
                self.state_change = True
                self.container.stop()

            if self.container.destroy():
                self.state_change = True

            # post destroy attempt sleep for 1 second.
            time.sleep(1)
        else:
            self.failure(
                lxc_container=self._container_data(),
                error='Failed to destroy container'
                      ' [ %s ]' % self.container_name,
                rc=1,
                msg='The container [ %s ] failed to be destroyed. Check'
                    ' that lxc is available and that the container is in a'
                    ' functional state.' % self.container_name
            )

    def _frozen(self, count=0):
        """Ensure a container is frozen.

        If the container does not exist the container will be created.

        :param count: number of times this command has been called by itself.
        :type count: ``int``
        """

        self.check_count(count=count, method='frozen')
        if self._container_exists(name=self.container_name):
            self._execute_command()

            # Perform any configuration updates
            self._config()

            container_state = self._get_state()
            if container_state == 'frozen':
                pass
            elif container_state == 'running':
                self.container.freeze()
                self.state_change = True
            else:
                self._container_startup()
                self.container.freeze()
                self.state_change = True

            # Check if the container needs to have an archive created.
            self._check_archive()
        else:
            self._create()
            count += 1
            self._frozen(count)

    def _restarted(self, count=0):
        """Ensure a container is restarted.

        If the container does not exist the container will be created.

        :param count: number of times this command has been called by itself.
        :type count: ``int``
        """

        self.check_count(count=count, method='restart')
        if self._container_exists(name=self.container_name):
            self._execute_command()

            # Perform any configuration updates
            self._config()

            if self._get_state() != 'stopped':
                self.container.stop()
                self.state_change = True

            # Check if the container needs to have an archive created.
            self._check_archive()
        else:
            self._create()
            count += 1
            self._restarted(count)

    def _stopped(self, count=0):
        """Ensure a container is stopped.

        If the container does not exist the container will be created.

        :param count: number of times this command has been called by itself.
        :type count: ``int``
        """

        self.check_count(count=count, method='stop')
        if self._container_exists(name=self.container_name):
            self._execute_command()

            # Perform any configuration updates
            self._config()

            if self._get_state() != 'stopped':
                self.container.stop()
                self.state_change = True

            # Check if the container needs to have an archive created.
            self._check_archive()
        else:
            self._create()
            count += 1
            self._stopped(count)

    def _started(self, count=0):
        """Ensure a container is started.

        If the container does not exist the container will be created.

        :param count: number of times this command has been called by itself.
        :type count: ``int``
        """

        self.check_count(count=count, method='start')
        if self._container_exists(name=self.container_name):
            container_state = self._get_state()
            if container_state == 'running':
                pass
            elif container_state == 'frozen':
                self._unfreeze()
            elif not self._container_startup():
                self.failure(
                    lxc_container=self._container_data(),
                    error='Failed to start container'
                          ' [ %s ]' % self.container_name,
                    rc=1,
                    msg='The container [ %s ] failed to start. Check to lxc is'
                        ' available and that the container is in a functional'
                        ' state.' % self.container_name
                )

            # Return data
            self._execute_command()

            # Perform any configuration updates
            self._config()

            # Check if the container needs to have an archive created.
            self._check_archive()
        else:
            self._create()
            count += 1
            self._started(count)

    def _get_lxc_vg(self):
        """Return the name of the Volume Group used in LXC."""

        build_command = [
            self.module.get_bin_path('lxc-config', True),
            "lxc.bdev.lvm.vg"
        ]
        rc, vg, err = self._run_command(build_command)
        if rc != 0:
            self.failure(
                err=err,
                rc=rc,
                msg='Failed to read LVM VG from LXC config',
                command=' '.join(build_command)
            )
        else:
            return str(vg.strip())

    def _lvm_lv_list(self):
        """Return a list of all lv in a current vg."""

        vg = self._get_lxc_vg()
        build_command = [
            self.module.get_bin_path('lvs', True)
        ]
        rc, stdout, err = self._run_command(build_command)
        if rc != 0:
            self.failure(
                err=err,
                rc=rc,
                msg='Failed to get list of LVs',
                command=' '.join(build_command)
            )

        all_lvms = [i.split() for i in stdout.splitlines()][1:]
        return [lv_entry[0] for lv_entry in all_lvms if lv_entry[1] == vg]

    def _get_vg_free_pe(self, name):
        """Return the available size of a given VG.

        :param name: Name of volume.
        :type name: ``str``
        :returns: size and measurement of an LV
        :type: ``tuple``
        """

        build_command = [
            'vgdisplay',
            name,
            '--units',
            'g'
        ]
        rc, stdout, err = self._run_command(build_command)
        if rc != 0:
            self.failure(
                err=err,
                rc=rc,
                msg='failed to read vg %s' % name,
                command=' '.join(build_command)
            )

        vg_info = [i.strip() for i in stdout.splitlines()][1:]
        free_pe = [i for i in vg_info if i.startswith('Free')]
        _free_pe = free_pe[0].split()
        return float(_free_pe[-2]), _free_pe[-1]

    def _get_lv_size(self, name):
        """Return the available size of a given LV.

        :param name: Name of volume.
        :type name: ``str``
        :returns: size and measurement of an LV
        :type: ``tuple``
        """

        vg = self._get_lxc_vg()
        lv = os.path.join(vg, name)
        build_command = [
            'lvdisplay',
            lv,
            '--units',
            'g'
        ]
        rc, stdout, err = self._run_command(build_command)
        if rc != 0:
            self.failure(
                err=err,
                rc=rc,
                msg='failed to read lv %s' % lv,
                command=' '.join(build_command)
            )

        lv_info = [i.strip() for i in stdout.splitlines()][1:]
        _free_pe = [i for i in lv_info if i.startswith('LV Size')]
        free_pe = _free_pe[0].split()
        return self._roundup(float(free_pe[-2])), free_pe[-1]

    def _lvm_snapshot_create(self, source_lv, snapshot_name,
                             snapshot_size_gb=5):
        """Create an LVM snapshot.

        :param source_lv: Name of lv to snapshot
        :type source_lv: ``str``
        :param snapshot_name: Name of lv snapshot
        :type snapshot_name: ``str``
        :param snapshot_size_gb: Size of snapshot to create
        :type snapshot_size_gb: ``int``
        """

        vg = self._get_lxc_vg()
        free_space, messurement = self._get_vg_free_pe(name=vg)

        if free_space < float(snapshot_size_gb):
            message = (
                'Snapshot size [ %s ] is > greater than [ %s ] on volume group'
                ' [ %s ]' % (snapshot_size_gb, free_space, vg)
            )
            self.failure(
                error='Not enough space to create snapshot',
                rc=2,
                msg=message
            )

        # Create LVM Snapshot
        build_command = [
            self.module.get_bin_path('lvcreate', True),
            "-n",
            snapshot_name,
            "-s",
            os.path.join(vg, source_lv),
            "-L%sg" % snapshot_size_gb
        ]
        rc, stdout, err = self._run_command(build_command)
        if rc != 0:
            self.failure(
                err=err,
                rc=rc,
                msg='Failed to Create LVM snapshot %s/%s --> %s'
                    % (vg, source_lv, snapshot_name)
            )

    def _lvm_lv_mount(self, lv_name, mount_point):
        """mount an lv.

        :param lv_name: name of the logical volume to mount
        :type lv_name: ``str``
        :param mount_point: path on the file system that is mounted.
        :type mount_point: ``str``
        """

        vg = self._get_lxc_vg()

        build_command = [
            self.module.get_bin_path('mount', True),
            "/dev/%s/%s" % (vg, lv_name),
            mount_point,
        ]
        rc, stdout, err = self._run_command(build_command)
        if rc != 0:
            self.failure(
                err=err,
                rc=rc,
                msg='failed to mountlvm lv %s/%s to %s'
                    % (vg, lv_name, mount_point)
            )

    def _create_tar(self, source_dir):
        """Create an archive of a given ``source_dir`` to ``output_path``.

        :param source_dir:  Path to the directory to be archived.
        :type source_dir: ``str``
        """

        archive_path = self.module.params.get('archive_path')
        if not os.path.isdir(archive_path):
            os.makedirs(archive_path)

        archive_compression = self.module.params.get('archive_compression')
        compression_type = LXC_COMPRESSION_MAP[archive_compression]

        # remove trailing / if present.
        archive_name = '%s.%s' % (
            os.path.join(
                archive_path,
                self.container_name
            ),
            compression_type['extension']
        )

        build_command = [
            self.module.get_bin_path('tar', True),
            '--directory=%s' % os.path.realpath(
                os.path.expanduser(source_dir)
            ),
            compression_type['argument'],
            archive_name,
            '.'
        ]

        rc, stdout, err = self._run_command(
            build_command=build_command,
            unsafe_shell=True
        )
        if rc != 0:
            self.failure(
                err=err,
                rc=rc,
                msg='failed to create tar archive',
                command=' '.join(build_command)
            )

        return archive_name

    def _lvm_lv_remove(self, name):
        """Remove an LV.

        :param name: The name of the logical volume
        :type name: ``str``
        """

        vg = self._get_lxc_vg()
        build_command = [
            self.module.get_bin_path('lvremove', True),
            "-f",
            "%s/%s" % (vg, name),
        ]
        rc, stdout, err = self._run_command(build_command)
        if rc != 0:
            self.failure(
                err=err,
                rc=rc,
                msg='Failed to remove LVM LV %s/%s' % (vg, name),
                command=' '.join(build_command)
            )

    def _rsync_data(self, container_path, temp_dir):
        """Sync the container directory to the temp directory.

        :param container_path: path to the container container
        :type container_path: ``str``
        :param temp_dir: path to the temporary local working directory
        :type temp_dir: ``str``
        """

        build_command = [
            self.module.get_bin_path('rsync', True),
            '-aHAX',
            container_path,
            temp_dir
        ]
        rc, stdout, err = self._run_command(build_command, unsafe_shell=True)
        if rc != 0:
            self.failure(
                err=err,
                rc=rc,
                msg='failed to perform archive',
                command=' '.join(build_command)
            )

    def _unmount(self, mount_point):
        """Unmount a file system.

        :param mount_point: path on the file system that is mounted.
        :type mount_point: ``str``
        """

        build_command = [
            self.module.get_bin_path('umount', True),
            mount_point,
        ]
        rc, stdout, err = self._run_command(build_command)
        if rc != 0:
            self.failure(
                err=err,
                rc=rc,
                msg='failed to unmount [ %s ]' % mount_point,
                command=' '.join(build_command)
            )

    def _container_create_tar(self):
        """Create a tar archive from an LXC container.

        The process is as follows:
            * Stop or Freeze the container
            * Create temporary dir
            * Copy container and config to temporary directory
            * If LVM backed:
                * Create LVM snapshot of LV backing the container
                * Mount the snapshot to tmpdir/rootfs
            * Restore the state of the container
            * Create tar of tmpdir
            * Clean up
        """

        # Create a temp dir
        temp_dir = tempfile.mkdtemp()

        # Set the name of the working dir, temp + container_name
        work_dir = os.path.join(temp_dir, self.container_name)

        # LXC container rootfs
        lxc_rootfs = self.container.get_config_item('lxc.rootfs')

        # Test if the containers rootfs is a block device
        block_backed = lxc_rootfs.startswith(os.path.join(os.sep, 'dev'))
        mount_point = os.path.join(work_dir, 'rootfs')

        # Set the snapshot name if needed
        snapshot_name = '%s_lxc_snapshot' % self.container_name

        # Set the path to the container data
        container_path = os.path.dirname(lxc_rootfs)
        container_state = self._get_state()
        try:
            # Ensure the original container is stopped or frozen
            if container_state not in ['stopped', 'frozen']:
                if container_state == 'running':
                    self.container.freeze()
                else:
                    self.container.stop()

            # Sync the container data from the container_path to work_dir
            self._rsync_data(container_path, temp_dir)

            if block_backed:
                if snapshot_name not in self._lvm_lv_list():
                    if not os.path.exists(mount_point):
                        os.makedirs(mount_point)

                    # Take snapshot
                    size, measurement = self._get_lv_size(
                        name=self.container_name
                    )
                    self._lvm_snapshot_create(
                        source_lv=self.container_name,
                        snapshot_name=snapshot_name,
                        snapshot_size_gb=size
                    )

                    # Mount snapshot
                    self._lvm_lv_mount(
                        lv_name=snapshot_name,
                        mount_point=mount_point
                    )
                else:
                    self.failure(
                        err='snapshot [ %s ] already exists' % snapshot_name,
                        rc=1,
                        msg='The snapshot [ %s ] already exists. Please clean'
                            ' up old snapshot of containers before continuing.'
                            % snapshot_name
                    )

            # Restore original state of container
            if container_state == 'running':
                if self._get_state() == 'frozen':
                    self.container.unfreeze()
                else:
                    self.container.start()

            # Set the state as changed and set a new fact
            self.state_change = True
            return self._create_tar(source_dir=work_dir)
        finally:
            if block_backed:
                # unmount snapshot
                self._unmount(mount_point)

                # Remove snapshot
                self._lvm_lv_remove(snapshot_name)

            # Remove tmpdir
            shutil.rmtree(temp_dir)

    def check_count(self, count, method):
        if count > 1:
            self.failure(
                error='Failed to %s container' % method,
                rc=1,
                msg='The container [ %s ] failed to %s. Check to lxc is'
                    ' available and that the container is in a functional'
                    ' state.' % (self.container_name, method)
            )

    def failure(self, **kwargs):
        """Return a Failure when running an Ansible command.

        :param error: ``str``  Error that occurred.
        :param rc: ``int``     Return code while executing an Ansible command.
        :param msg: ``str``    Message to report.
        """

        self.module.fail_json(**kwargs)

    def run(self):
        """Run the main method."""

        action = getattr(self, LXC_ANSIBLE_STATES[self.state])
        action()

        outcome = self._container_data()
        if self.archive_info:
            outcome.update(self.archive_info)

        self.module.exit_json(
            changed=self.state_change,
            lxc_container=outcome
        )


def main():
    """Ansible Main module."""

    module = AnsibleModule(
        argument_spec=dict(
            name=dict(
                type='str',
                required=True
            ),
            template=dict(
                type='str',
                default='ubuntu'
            ),
            backing_store=dict(
                type='str',
                choices=LXC_BACKING_STORE.keys(),
                default='dir'
            ),
            template_options=dict(
                type='str'
            ),
            config=dict(
                type='str',
                default='/etc/lxc/default.conf'
            ),
            vg_name=dict(
                type='str',
                default='lxc'
            ),
            thinpool=dict(
                type='str'
            ),
            fs_type=dict(
                type='str',
                default='ext4'
            ),
            fs_size=dict(
                type='str',
                default='5G'
            ),
            directory=dict(
                type='str'
            ),
            zfs_root=dict(
                type='str'
            ),
            lv_name=dict(
                type='str'
            ),
            lxc_path=dict(
                type='str'
            ),
            state=dict(
                choices=LXC_ANSIBLE_STATES.keys(),
                default='started'
            ),
            container_command=dict(
                type='str'
            ),
            container_config=dict(
                type='str'
            ),
            container_log=dict(
                choices=BOOLEANS,
                default='false'
            ),
            container_log_level=dict(
                choices=[n for i in LXC_LOGGING_LEVELS.values() for n in i],
                default='INFO'
            ),
            archive=dict(
                choices=BOOLEANS,
                default='false'
            ),
            archive_path=dict(
                type='str',
                default='/tmp'
            ),
            archive_compression=dict(
                choices=LXC_COMPRESSION_MAP.keys(),
                default='gzip'
            )
        ),
        supports_check_mode=False,
    )

    lv_name = module.params.get('lv_name')
    if not lv_name:
        module.params['lv_name'] = module.params.get('name')

    lxc_manage = LxcContainerManagement(module=module)
    lxc_manage.run()


# import module bits
from ansible.module_utils.basic import *
main()