docker.py

#!/usr/bin/env python
#
# (c) 2016 Paul Durivage <paul.durivage@gmail.com>
#          Chris Houseknecht <house@redhat.com>
#          James Tanner <jtanner@redhat.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/>.
#

DOCUMENTATION = '''

Docker Inventory Script
=======================
Generates dynamic inventory by making API requests to one or more Docker daemons. Communicates with the API
by way of docker-py (https://docker-py.readthedocs.org/en/stable/). So before running the script, you will need to
install docker-py:

   pip install docker-py


Run for Specific Host
---------------------
When run for a specific container using the --host option this script returns the following hostvars:

{
    "ansible_ssh_host": "",
    "ansible_ssh_port": 0,
    "docker_apparmorprofile": "",
    "docker_args": [],
    "docker_config": {
        "AttachStderr": false,
        "AttachStdin": false,
        "AttachStdout": false,
        "Cmd": [
            "/hello"
        ],
        "Domainname": "",
        "Entrypoint": null,
        "Env": null,
        "Hostname": "9f2f80b0a702",
        "Image": "hello-world",
        "Labels": {},
        "OnBuild": null,
        "OpenStdin": false,
        "StdinOnce": false,
        "Tty": false,
        "User": "",
        "Volumes": null,
        "WorkingDir": ""
    },
    "docker_created": "2016-04-18T02:05:59.659599249Z",
    "docker_driver": "aufs",
    "docker_execdriver": "native-0.2",
    "docker_execids": null,
    "docker_graphdriver": {
        "Data": null,
        "Name": "aufs"
    },
    "docker_hostconfig": {
        "Binds": null,
        "BlkioWeight": 0,
        "CapAdd": null,
        "CapDrop": null,
        "CgroupParent": "",
        "ConsoleSize": [
            0,
            0
        ],
        "ContainerIDFile": "",
        "CpuPeriod": 0,
        "CpuQuota": 0,
        "CpuShares": 0,
        "CpusetCpus": "",
        "CpusetMems": "",
        "Devices": null,
        "Dns": null,
        "DnsOptions": null,
        "DnsSearch": null,
        "ExtraHosts": null,
        "GroupAdd": null,
        "IpcMode": "",
        "KernelMemory": 0,
        "Links": null,
        "LogConfig": {
            "Config": {},
            "Type": "json-file"
        },
        "LxcConf": null,
        "Memory": 0,
        "MemoryReservation": 0,
        "MemorySwap": 0,
        "MemorySwappiness": null,
        "NetworkMode": "default",
        "OomKillDisable": false,
        "PidMode": "host",
        "PortBindings": null,
        "Privileged": false,
        "PublishAllPorts": false,
        "ReadonlyRootfs": false,
        "RestartPolicy": {
            "MaximumRetryCount": 0,
            "Name": ""
        },
        "SecurityOpt": [
            "label:disable"
        ],
        "UTSMode": "",
        "Ulimits": null,
        "VolumeDriver": "",
        "VolumesFrom": null
    },
    "docker_hostnamepath": "/mnt/sda1/var/lib/docker/containers/9f2f80b0a702361d1ac432e6af816c19bda46da15c21264fb418c873de635a14/hostname",
    "docker_hostspath": "/mnt/sda1/var/lib/docker/containers/9f2f80b0a702361d1ac432e6af816c19bda46da15c21264fb418c873de635a14/hosts",
    "docker_id": "9f2f80b0a702361d1ac432e6af816c19bda46da15c21264fb418c873de635a14",
    "docker_image": "0a6ba66e537a53a5ea94f7c6a99c534c6adb12e3ed09326d4bf3b38f7c3ba4e7",
    "docker_logpath": "/mnt/sda1/var/lib/docker/containers/9f2f80b0a702361d1ac432e6af816c19bda46da15c21264fb418c873de635a14/9f2f80b0a702361d1ac432e6af816c19bda46da15c21264fb418c873de635a14-json.log",
    "docker_mountlabel": "",
    "docker_mounts": [],
    "docker_name": "/hello-world",
    "docker_networksettings": {
        "Bridge": "",
        "EndpointID": "",
        "Gateway": "",
        "GlobalIPv6Address": "",
        "GlobalIPv6PrefixLen": 0,
        "HairpinMode": false,
        "IPAddress": "",
        "IPPrefixLen": 0,
        "IPv6Gateway": "",
        "LinkLocalIPv6Address": "",
        "LinkLocalIPv6PrefixLen": 0,
        "MacAddress": "",
        "Networks": {
            "bridge": {
                "EndpointID": "",
                "Gateway": "",
                "GlobalIPv6Address": "",
                "GlobalIPv6PrefixLen": 0,
                "IPAddress": "",
                "IPPrefixLen": 0,
                "IPv6Gateway": "",
                "MacAddress": ""
            }
        },
        "Ports": null,
        "SandboxID": "",
        "SandboxKey": "",
        "SecondaryIPAddresses": null,
        "SecondaryIPv6Addresses": null
    },
    "docker_path": "/hello",
    "docker_processlabel": "",
    "docker_resolvconfpath": "/mnt/sda1/var/lib/docker/containers/9f2f80b0a702361d1ac432e6af816c19bda46da15c21264fb418c873de635a14/resolv.conf",
    "docker_restartcount": 0,
    "docker_short_id": "9f2f80b0a7023",
    "docker_state": {
        "Dead": false,
        "Error": "",
        "ExitCode": 0,
        "FinishedAt": "2016-04-18T02:06:00.296619369Z",
        "OOMKilled": false,
        "Paused": false,
        "Pid": 0,
        "Restarting": false,
        "Running": false,
        "StartedAt": "2016-04-18T02:06:00.272065041Z",
        "Status": "exited"
    }
}

Groups
------
When run in --list mode (the default), container instances are grouped by:

 - container id
 - container name
 - container short id
 - image_name  (image_<image name>)
 - docker_host
 - running
 - stopped


Configuration:
--------------
You can control the behavior of the inventory script by passing arguments, defining environment variables, or
creating a docker.yml file (sample provided in ansible/contrib/inventory). The order of precedence is command
line args, then the docker.yml file and finally environment variables.

Environment variables:
;;;;;;;;;;;;;;;;;;;;;;

DOCKER_CONFIG_FILE
   description: path to docker inventory configuration file.
   default: ./docker.yml

DOCKER_HOST
   description: Docker daemon URL or Unix socket path.
   default: unix://var/run/docker.sock

DOCKER_TLS_HOSTNAME:
   description: When DOCKER_TLS_VERIFY is true, provide the expected name of the host.
   default: localhost

DOCKER_API_VERSION:
   description: Version of the Docker API the client will use.
   default: DEFAULT_DOCKER_API_VERSION as defined in docker-py

DOCKER_CERT_PATH:
   description: Path to the directory containing the client certificate and key files.
   default: None

DOCKER_SSL_VERSION:
   description: Version of TLS supported by Docker daemon.
   default: None

DOCKER_TLS:
   description: Use TLS when sending requests to Docker daemon. Set to 1, 0, true, false, True, False, yes, no.
   default: False

DOCKER_TLS_VERIFY:
   description: Verify hostname found in TLS certs. Set to 1, 0, true, false, True, False, yes, no.
   default: False

DOCKER_TIMEOUT:
   description: Docker request timeout in seconds.
   default: Value of DOCKER_TIMEOUT as defined in docker-py

DOCKER_PRIVATE_SSH_PORT:
   description: The private port (container port) on which SSH is listening for connections
   default: 22

DOCKER_DEFAULT_IP:
   description: This environment variable overrides the container SSH connection
      IP address (aka, 'ansible_ssh_host').

      This option allows one to override the ansible_ssh_host whenever Docker has exercised its default behavior of
      binding private ports to all interfaces of the Docker host.  This behavior, when dealing with remote Docker hosts,
      does not allow Ansible to determine a proper host IP address on which to connect via SSH to containers. By
      default, this inventory module assumes all 0.0.0.0-exposed ports to be bound to localhost:<port>.  To override
      this behavior, for example, to bind a container's SSH port to the public interface of its host, one must
      manually set this IP.

      It is preferable to begin to launch Docker containers with ports exposed on publicly accessible IP addresses,
      particularly if the containers are to be targeted by Ansible for remote configuration, not accessible via
      localhost SSH connections. Docker containers can be explicitly exposed on IP addresses by
         a) starting the daemon with the --ip argument
         b) running containers with the -P/--publish ip::containerPort
            argument
   default: 127.0.0.1 if port exposed on 0.0.0.0


docker.yml
;;;;;;;;;;;;;;;;;;;;

A sample docker.yml file is included in the ansible/contrib/inventory. Using this file is not required. If
the file is not found, environment variables will be used.

The default name of the file is derived from the name of the inventory script. By default the script will look for
basename of the script (i.e. docker) with an extension of '.yml'. You can override the default name by passing a 
command line argument or setting DOCKER_CONFIG_FILE in the environment.

Here's what you can define in docker_inventory.yml:

  * defaults: Defines a default connnection. Defaults will be taken from this and applied to any values not provided
    for a host defined in the hosts list.

  * hosts: If you wish to get inventory from more than one Docker daemon hosts, define a hosts list.

For a host defined in defaults or hosts, you can provided the following attributes. The only required attribute is host.

  host:
      description: The URL or Unix socket path for the host.
      required: yes
  tls:
     description: Connect using https://
     default: false
     required: false
  tls_verify:
     description: Connect using https:// and verify the host name matches the host name found in the certificate.
     default: false
     required: false
  cert_path:
     description: Path to the host's certificate .pem file.
     default: null
     required: false
  cacert_path:
     description: Path to the host's Certificate Authority .pem file.
     default: null
     required: false
  key_path:
     description: Path to the host's encryption key .pem file
     default: null
     required: false
  version:
     description: The API version.
     required: false
     default: will be supplied by the docker-py module.
  timeout:
     description: The amount of time in seconds to wait on an API response.
     required: false
     default: will be supplied by the docker-py module.
  default_ip:
     description: The IP address to assign to ansilbe_host when the container's SSH port is mappped to 0.0.0.0
     required: false
     default: 1267.0.0.1
  private_ssh_port:
     description: The port containers use for SSH
     required: false
     default: 22

Examples
--------
 # Run the script with Env vars (for when you have Docker toolbox installed)
 ./docker_inventory.py --pretty

 # Connect to docker instance on localhost port 4243
 DOCKER_HOST=tcp://localhost:4243 ./docker.py --pretty

 # Any container's ssh port exposed on 0.0.0.0 will mapped to
 #another IP address (where Ansible will attempt to connect via SSH)
 DOCKER_DEFAULT_IP=1.2.3.4 ./docker.py --pretty

 # Run as input to a playbook:
 ansible-playbook -i ~/projects/ansible/contrib/inventory/docker_inventory.py docker_inventory_test.yml

 # Simple playbook to invoke with the above example:

    - name: Test docker_inventory
      hosts: all
      connection: local
      gather_facts: no
      tasks:
         - debug: msg="Container - {{ inventory_hostname }}"


'''

import os
import sys
import json
import argparse
import re
import yaml

from collections import defaultdict
# Manipulation of the path is needed because the docker-py
# module is imported by the name docker, and because this file
# is also named docker
for path in [os.getcwd(), '', os.path.dirname(os.path.abspath(__file__))]:
    try:
        del sys.path[sys.path.index(path)]
    except:
        pass

HAS_DOCKER_PY = True
HAS_DOCKER_ERROR = False

try:
    from docker import Client
    from docker.errors import APIError, TLSParameterError
    from docker.tls import TLSConfig
    from docker.constants import DEFAULT_TIMEOUT_SECONDS, DEFAULT_DOCKER_API_VERSION
except ImportError, exc:
    HAS_DOCKER_ERROR = str(exc)
    HAS_DOCKER_PY = False

DEFAULT_DOCKER_HOST = 'unix://var/run/docker.sock'
DEFAULT_TLS = False
DEFAULT_TLS_VERIFY = False
DEFAULT_IP = '127.0.0.1'
DEFAULT_SSH_PORT = '22'

BOOLEANS_TRUE = ['yes', 'on', '1', 'true', 1, True]
BOOLEANS_FALSE = ['no', 'off', '0', 'false', 0, False]


DOCKER_ENV_ARGS = dict(
    config_file='DOCKER_CONFIG_FILE',
    docker_host='DOCKER_HOST',
    api_version='DOCKER_API_VERSION',
    cert_path='DOCKER_CERT_PATH',
    ssl_version='DOCKER_SSL_VERSION',
    tls='DOCKER_TLS',
    tls_verify='DOCKER_TLS_VERIFY',
    timeout='DOCKER_TIMEOUT',
    private_ssh_port='DOCKER_DEFAULT_SSH_PORT',
    default_ip='DOCKER_DEFAULT_IP',
)


def fail(msg):
    sys.stderr.write("%s\n" % msg)
    sys.exit(1)


def log(msg, pretty_print=False):
    if pretty_print:
        print(json.dumps(msg, sort_keys=True, indent=2))
    else:
        print(msg + u'\n')


class AnsibleDockerClient(Client):
    def __init__(self, auth_params, debug):

        self.auth_params = auth_params
        self.debug = debug
        self._connect_params = self._get_connect_params()

        try:
            super(AnsibleDockerClient, self).__init__(**self._connect_params)
        except APIError, exc:
            self.fail("Docker API error: %s" % exc)
        except Exception, exc:
            self.fail("Error connecting: %s" % exc)

    def fail(self, msg):
        fail(msg)

    def log(self, msg, pretty_print=False):
        if self.debug:
            log(msg, pretty_print)

    def _get_tls_config(self, **kwargs):
        self.log("get_tls_config:")
        for key in kwargs:
            self.log("  %s: %s" % (key, kwargs[key]))
        try:
            tls_config = TLSConfig(**kwargs)
            return tls_config
        except TLSParameterError, exc:
           self.fail("TLS config error: %s" % exc)

    def _get_connect_params(self):
        auth = self.auth_params

        self.log("auth params:")
        for key in auth:
            self.log("  %s: %s" % (key, auth[key]))

        if auth['tls'] or auth['tls_verify']:
            auth['docker_host'] = auth['docker_host'].replace('tcp://', 'https://')

        if auth['tls'] and auth['cert_path'] and auth['key_path']:
            # TLS with certs and no host verification
            tls_config = self._get_tls_config(client_cert=(auth['cert_path'], auth['key_path']),
                                              verify=False,
                                              ssl_version=auth['ssl_version'])
            return dict(base_url=auth['docker_host'],
                        tls=tls_config,
                        version=auth['api_version'],
                        timeout=auth['timeout'])

        if auth['tls']:
            # TLS with no certs and not host verification
            tls_config = self._get_tls_config(verify=False,
                                              ssl_version=auth['ssl_version'])
            return dict(base_url=auth['docker_host'],
                        tls=tls_config,
                        version=auth['api_version'],
                        timeout=auth['timeout'])

        if auth['tls_verify'] and auth['cert_path'] and auth['key_path']:
            # TLS with certs and host verification
            if auth['cacert_path']:
                tls_config = self._get_tls_config(client_cert=(auth['cert_path'], auth['key_path']),
                                                  ca_cert=auth['cacert_path'],
                                                  verify=True,
                                                  assert_hostname=auth['tls_hostname'],
                                                  ssl_version=auth['ssl_version'])
            else:
                tls_config = self._get_tls_config(client_cert=(auth['cert_path'], auth['key_path']),
                                                  verify=True,
                                                  assert_hostname=auth['tls_hostname'],
                                                  ssl_version=auth['ssl_version'])

            return dict(base_url=auth['docker_host'],
                        tls=tls_config,
                        version=auth['api_version'],
                        timeout=auth['timeout'])

        if auth['tls_verify'] and auth['cacert_path']:
            # TLS with cacert only
            tls_config = self._get_tls_config(ca_cert=auth['cacert_path'],
                                              assert_hostname=auth['tls_hostname'],
                                              verify=True,
                                              ssl_version=auth['ssl_version'])
            return dict(base_url=auth['docker_host'],
                        tls=tls_config,
                        version=auth['api_version'],
                        timeout=auth['timeout'])

        if auth['tls_verify']:
            # TLS with verify and no certs
            tls_config = self._get_tls_config(verify=True,
                                              assert_hostname=auth['tls_hostname'],
                                              ssl_version=auth['ssl_version'])
            return dict(base_url=auth['docker_host'],
                        tls=tls_config,
                        version=auth['api_version'],
                        timeout=auth['timeout'])
        # No TLS
        return dict(base_url=auth['docker_host'],
                    version=auth['api_version'],
                    timeout=auth['timeout'])

    def _handle_ssl_error(self, error):
        match = re.match(r"hostname.*doesn\'t match (\'.*\')", str(error))
        if match:
            msg = "You asked for verification that Docker host name matches %s. The actual hostname is %s. " \
                "Most likely you need to set DOCKER_TLS_HOSTNAME or pass tls_hostname with a value of %s. " \
                "You may also use TLS without verification by setting the tls parameter to true." \
                 % (self.auth_params['tls_hostname'], match.group(1))
            self.fail(msg)
        self.fail("SSL Exception: %s" % (error))


class EnvArgs(object):
    def __init__(self):
        self.config_file = None
        self.docker_host = None
        self.api_version = None
        self.cert_path = None
        self.ssl_version = None
        self.tls = None
        self.tls_verify = None
        self.tls_hostname = None
        self.timeout = None
        self.default_ssh_port = None
        self.default_ip = None


class DockerInventory(object):

    def __init__(self):
        self._args = self._parse_cli_args()
        self._env_args = self._parse_env_args()
        self.groups = defaultdict(list)
        self.hostvars = defaultdict(dict)

    def run(self):
        config_from_file = self._parse_config_file()
        if not config_from_file:
            config_from_file = dict()
        docker_hosts = self.get_hosts(config_from_file)

        for host in docker_hosts:
            client = AnsibleDockerClient(host, self._args.debug)
            self.get_inventory(client, host)

        if not self._args.host:
            self.groups['docker_hosts'] = [host.get('docker_host') for host in docker_hosts]
            self.groups['_meta'] = dict(
                hostvars=self.hostvars
            )
            print(self._json_format_dict(self.groups, pretty_print=self._args.pretty))
        else:
            print(self._json_format_dict(self.hostvars.get(self._args.host, dict()), pretty_print=self._args.pretty))

        sys.exit(0)

    def get_inventory(self, client, host):

        ssh_port = host.get('default_ssh_port')
        default_ip = host.get('default_ip')
        hostname = host.get('docker_host')

        try:
            containers = client.containers(all=True)
        except Exception as exc:
            self.fail("Error fetching containers for host %s - %s" % (hostname, str(exc)))

        for container in containers:
            id = container.get('Id')
            short_id = id[:13]

            try:
                name = container.get('Names', list()).pop(0).lstrip('/')
            except IndexError:
                name = short_id

            if not self._args.host or (self._args.host and self._args.host in [name, id, short_id]):
                try:
                    inspect = client.inspect_container(id)
                except Exception as exc:
                    self.fail("Error inspecting container %s - %s" % (name, str(exc)))

                running = inspect.get('State', dict()).get('Running')

                # Add container to groups
                image_name = inspect.get('Config', dict()).get('Image')
                if image_name:
                    self.groups["image_%s" % (image_name)].append(name)

                self.groups[id].append(name)
                self.groups[name].append(name)
                if short_id not in self.groups.keys():
                    self.groups[short_id].append(name)
                self.groups[hostname].append(name)

                if running is True:
                    self.groups['running'].append(name)
                else:
                    self.groups['stopped'].append(name)

                # Figure ous ssh IP and Port
                try:
                    # Lookup the public facing port Nat'ed to ssh port.
                    port = client.port(container, ssh_port)[0]
                except (IndexError, AttributeError, TypeError):
                    port = dict()

                try:
                    ip = default_ip if port['HostIp'] == '0.0.0.0' else port['HostIp']
                except KeyError:
                    ip = ''

                facts = dict(
                    ansible_ssh_host=ip,
                    ansible_ssh_port=port.get('HostPort', int()),
                    docker_name=name,
                    docker_short_id=short_id
                )

                for key in inspect:
                    fact_key = self._slugify(key)
                    facts[fact_key] = inspect.get(key)

                self.hostvars[name].update(facts)

    def _slugify(self, value):
        return 'docker_%s' % (re.sub('[^\w-]', '_', value).lower().lstrip('_'))

    def get_hosts(self, config):
        '''
        Determine the list of docker hosts we need to talk to.

        :param config: dictionary read from config file. can be empty.
        :return: list of connection dictionaries
        '''
        hosts = list()

        hosts_list = config.get('hosts')
        defaults = config.get('defaults', dict())
        self.log('defaults:')
        self.log(defaults, pretty_print=True)
        def_host = defaults.get('host')
        def_tls = defaults.get('tls')
        def_tls_verify = defaults.get('tls_verify')
        def_tls_hostname = defaults.get('tls_hostname')
        def_ssl_version = defaults.get('ssl_version')
        def_cert_path = defaults.get('cert_path')
        def_cacert_path = defaults.get('cacert_path')
        def_key_path = defaults.get('key_path')
        def_version = defaults.get('version')
        def_timeout = defaults.get('timeout')
        def_ip = defaults.get('default_ip')
        def_ssh_port = defaults.get('private_ssh_port')

        if hosts_list:
            # use hosts from config file
            for host in hosts_list:
                docker_host = host.get('host') or def_host or self._args.docker_host or \
                              self._env_args.docker_host or DEFAULT_DOCKER_HOST
                api_version = host.get('version') or def_version or self._args.api_version or \
                    self._env_args.api_version or DEFAULT_DOCKER_API_VERSION
                tls_hostname = host.get('tls_hostname') or def_tls_hostname or self._args.tls_hostname or \
                    self._env_args.tls_hostname
                tls_verify = host.get('tls_verify') or def_tls_verify or self._args.tls_verify or \
                    self._env_args.tls_verify or DEFAULT_TLS_VERIFY
                tls = host.get('tls') or def_tls or self._args.tls or self._env_args.tls or DEFAULT_TLS
                ssl_version = host.get('ssl_version') or def_ssl_version or self._args.ssl_version or \
                    self._env_args.ssl_version

                cert_path = host.get('cert_path') or def_cert_path or self._args.cert_path or \
                    self._env_args.cert_path
                if cert_path and cert_path == self._env_args.cert_path:
                    cert_path = os.path.join(cert_path, 'cert.pem')

                cacert_path = host.get('cacert_path') or def_cacert_path or self._args.cacert_path or \
                    self._env_args.cert_path
                if cacert_path and cacert_path == self._env_args.cert_path:
                    cacert_path = os.path.join(cacert_path, 'ca.pem')

                key_path = host.get('key_path') or def_key_path or self._args.key_path or \
                    self._env_args.cert_path
                if key_path and key_path == self._env_args.cert_path:
                    key_path = os.path.join(key_path, 'key.pem')

                timeout = host.get('timeout') or def_timeout or self._args.timeout or self._env_args.timeout or \
                    DEFAULT_TIMEOUT_SECONDS
                default_ip = host.get('default_ip') or def_ip or self._args.default_ip_address or \
                    DEFAULT_IP
                default_ssh_port = host.get('private_ssh_port') or def_ssh_port or self._args.private_ssh_port or \
                    DEFAULT_SSH_PORT
                host_dict = dict(
                    docker_host=docker_host,
                    api_version=api_version,
                    tls=tls,
                    tls_verify=tls_verify,
                    tls_hostname=tls_hostname,
                    cert_path=cert_path,
                    cacert_path=cacert_path,
                    key_path=key_path,
                    ssl_version=ssl_version,
                    timeout=timeout,
                    default_ip=default_ip,
                    default_ssh_port=default_ssh_port,
                )
                hosts.append(host_dict)
        else:
            # use default definition
            docker_host = def_host or self._args.docker_host or self._env_args.docker_host or DEFAULT_DOCKER_HOST
            api_version = def_version or self._args.api_version or self._env_args.api_version or \
                DEFAULT_DOCKER_API_VERSION
            tls_hostname = def_tls_hostname or self._args.tls_hostname or self._env_args.tls_hostname
            tls_verify = def_tls_verify or self._args.tls_verify or self._env_args.tls_verify or DEFAULT_TLS_VERIFY
            tls = def_tls or self._args.tls or self._env_args.tls or DEFAULT_TLS
            ssl_version = def_ssl_version or self._args.ssl_version or self._env_args.ssl_version

            cert_path = def_cert_path or self._args.cert_path or self._env_args.cert_path
            if cert_path and cert_path == self._env_args.cert_path:
                    cert_path = os.path.join(cert_path, 'cert.pem')

            cacert_path = def_cacert_path or self._args.cacert_path or self._env_args.cert_path
            if cacertpath and cacert_path == self._env_args.cert_path:
                cacert_path = os.path.join(cacert_path, 'ca.pem')

            key_path = def_key_path or self._args.key_path or self._env_args.cert_path
            if key_path and key_path == self._env_args.cert_path:
                key_path = os.path.join(key_path, 'key.pem')

            timeout = def_timeout or self._args.timeout or self._env_args.timeout or DEFAULT_TIMEOUT_SECONDS
            default_ip = def_ip or self._args.default_ip_address or DEFAULT_IP
            default_ssh_port = def_ssh_port or self._args.private_ssh_port or DEFAULT_SSH_PORT
            host_dict = dict(
                docker_host=docker_host,
                api_version=api_version,
                tls=tls,
                tls_verify=tls_verify,
                tls_hostname=tls_hostname,
                cert_path=cert_path,
                cacert_path=cacert_path,
                key_path=key_path,
                ssl_version=ssl_version,
                timeout=timeout,
                default_ip=default_ip,
                default_ssh_port=default_ssh_port,
            )
            hosts.append(host_dict)
        self.log("hosts: ")
        self.log(hosts, pretty_print=True)
        return hosts

    def _parse_config_file(self):
        config = dict()
        config_path = None

        if self._args.config_file:
            config_path = self._args.config_file
        elif self._env_args.config_file:
            config_path = self._env_args.config_file

        if config_path:
            try:
                config_file = os.path.abspath(config_path)
            except:
                config_file = None

            if config_file and os.path.exists(config_file):
                with open(config_file) as f:
                    try:
                        config = yaml.safe_load(f.read())
                    except Exception as exc:
                        self.fail("Error: parsing %s - %s" % (config_path, str(exc)))
        return config

    def log(self, msg, pretty_print=False):
        if self._args.debug:
            log(msg, pretty_print)

    def fail(self, msg):
        fail(msg)

    def _parse_env_args(self):
        args = EnvArgs()
        for key, value in DOCKER_ENV_ARGS.items():
            if os.environ.get(value):
                val = os.environ.get(value)
                if val in BOOLEANS_TRUE:
                    val = True
                if val in BOOLEANS_FALSE:
                    val = False
                setattr(args, key, val)
        return args

    def _parse_cli_args(self):
        # Parse command line arguments

        basename = os.path.splitext(os.path.basename(__file__))[0]
        default_config = basename + '.yml'

        parser = argparse.ArgumentParser(
                description='Return Ansible inventory for one or more Docker hosts.')
        parser.add_argument('--list', action='store_true', default=True,
                           help='List all containers (default: True)')
        parser.add_argument('--debug', action='store_true', default=False,
                           help='Send debug messages to STDOUT')
        parser.add_argument('--host', action='store',
                            help='Only get information for a specific container.')
        parser.add_argument('--pretty', action='store_true', default=False,
                           help='Pretty print JSON output(default: False)')
        parser.add_argument('--config-file', action='store', default=default_config,
                            help="Name of the config file to use. Default is %s" % (default_config))
        parser.add_argument('--docker-host', action='store', default=None,
                            help="The base url or Unix sock path to connect to the docker daemon. Defaults to %s"
                                  % (DEFAULT_DOCKER_HOST))
        parser.add_argument('--tls-hostname', action='store', default='localhost',
                            help="Host name to expect in TLS certs. Defaults to 'localhost'")
        parser.add_argument('--api-version', action='store', default=None,
                            help="Docker daemon API version. Defaults to %s" % (DEFAULT_DOCKER_API_VERSION))
        parser.add_argument('--timeout', action='store', default=None,
                            help="Docker connection timeout in seconds. Defaults to %s"
                                  % (DEFAULT_TIMEOUT_SECONDS))
        parser.add_argument('--cacert-path', action='store', default=None,
                            help="Path to the TLS certificate authority pem file.")
        parser.add_argument('--cert-path', action='store', default=None,
                            help="Path to the TLS certificate pem file.")
        parser.add_argument('--key-path', action='store', default=None,
                            help="Path to the TLS encryption key pem file.")
        parser.add_argument('--ssl-version', action='store', default=None,
                            help="TLS version number")
        parser.add_argument('--tls', action='store_true', default=None,
                            help="Use TLS. Defaults to %s" % (DEFAULT_TLS))
        parser.add_argument('--tls-verify', action='store_true', default=None,
                            help="Verify TLS certificates. Defaults to %s" % (DEFAULT_TLS_VERIFY))
        parser.add_argument('--private-ssh-port', action='store', default=None,
                            help="Default private container SSH Port. Defaults to %s" % (DEFAULT_SSH_PORT))
        parser.add_argument('--default-ip-address', action='store', default=None,
                            help="Default container SSH IP address. Defaults to %s" % (DEFAULT_IP))
        return parser.parse_args()

    def _json_format_dict(self, data, pretty_print=False):
        # format inventory data for output
        if pretty_print:
            return json.dumps(data, sort_keys=True, indent=4)
        else:
            return json.dumps(data)


def main():

    if not HAS_DOCKER_PY:
        fail("Failed to import docker-py. Try `pip install docker-py` - %s" % (HAS_DOCKER_ERROR))

    DockerInventory().run()

main()