config.py

# (C) Datadog, Inc. 2010-2016
# All rights reserved
# Licensed under Simplified BSD License (see LICENSE)

# stdlib
import ConfigParser
from cStringIO import StringIO
import glob
import imp
import inspect
import itertools
import logging
import logging.config
import logging.handlers
from optparse import OptionParser, Values
import os
import platform
import re
from socket import gaierror, gethostbyname
import string
import sys
import traceback
from urlparse import urlparse

# project
from util import check_yaml, get_os
from utils.platform import Platform
from utils.proxy import get_proxy
from utils.service_discovery.config import extract_agent_config
from utils.service_discovery.config_stores import CONFIG_FROM_FILE, TRACE_CONFIG
from utils.service_discovery.sd_backend import get_sd_backend, AUTO_CONFIG_DIR, SD_BACKENDS
from utils.subprocess_output import (
    get_subprocess_output,
    SubprocessOutputEmptyError,
)

# CONSTANTS
AGENT_VERSION = "5.8.0"
DATADOG_CONF = "datadog.conf"
UNIX_CONFIG_PATH = '/etc/dd-agent'
MAC_CONFIG_PATH = '/opt/datadog-agent/etc'
DEFAULT_CHECK_FREQUENCY = 15   # seconds
LOGGING_MAX_BYTES = 5 * 1024 * 1024

log = logging.getLogger(__name__)

OLD_STYLE_PARAMETERS = [
    ('apache_status_url', "apache"),
    ('cacti_mysql_server', "cacti"),
    ('couchdb_server', "couchdb"),
    ('elasticsearch', "elasticsearch"),
    ('haproxy_url', "haproxy"),
    ('hudson_home', "Jenkins"),
    ('memcache_', "memcached"),
    ('mongodb_server', "mongodb"),
    ('mysql_server', "mysql"),
    ('nginx_status_url', "nginx"),
    ('postgresql_server', "postgres"),
    ('redis_urls', "redis"),
    ('varnishstat', "varnish"),
    ('WMI', "WMI"),
]

NAGIOS_OLD_CONF_KEYS = [
    'nagios_log',
    'nagios_perf_cfg'
]

LEGACY_DATADOG_URLS = [
    "app.datadoghq.com",
    "app.datad0g.com",
]


class PathNotFound(Exception):
    pass


def get_parsed_args():
    parser = OptionParser()
    parser.add_option('-A', '--autorestart', action='store_true', default=False,
                      dest='autorestart')
    parser.add_option('-d', '--dd_url', action='store', default=None,
                      dest='dd_url')
    parser.add_option('-u', '--use-local-forwarder', action='store_true',
                      default=False, dest='use_forwarder')
    parser.add_option('-n', '--disable-dd', action='store_true', default=False,
                      dest="disable_dd")
    parser.add_option('-v', '--verbose', action='store_true', default=False,
                      dest='verbose',
                      help='Print out stacktraces for errors in checks')
    parser.add_option('-p', '--profile', action='store_true', default=False,
                      dest='profile', help='Enable Developer Mode')

    try:
        options, args = parser.parse_args()
    except SystemExit:
        # Ignore parse errors
        options, args = Values({'autorestart': False,
                                'dd_url': None,
                                'disable_dd': False,
                                'use_forwarder': False,
                                'verbose': False,
                                'profile': False}), []
    return options, args


def get_version():
    return AGENT_VERSION


# Return url endpoint, here because needs access to version number
def get_url_endpoint(default_url, endpoint_type='app'):
    parsed_url = urlparse(default_url)
    if parsed_url.netloc not in LEGACY_DATADOG_URLS:
        return default_url

    subdomain = parsed_url.netloc.split(".")[0]

    # Replace https://app.datadoghq.com in https://5-2-0-app.agent.datadoghq.com
    return default_url.replace(subdomain,
        "{0}-{1}.agent".format(
            get_version().replace(".", "-"),
            endpoint_type))


def skip_leading_wsp(f):
    "Works on a file, returns a file-like object"
    return StringIO("\n".join(map(string.strip, f.readlines())))


def _windows_commondata_path():
    """Return the common appdata path, using ctypes
    From http://stackoverflow.com/questions/626796/\
    how-do-i-find-the-windows-common-application-data-folder-using-python
    """
    import ctypes
    from ctypes import wintypes, windll

    CSIDL_COMMON_APPDATA = 35

    _SHGetFolderPath = windll.shell32.SHGetFolderPathW
    _SHGetFolderPath.argtypes = [wintypes.HWND,
                                 ctypes.c_int,
                                 wintypes.HANDLE,
                                 wintypes.DWORD, wintypes.LPCWSTR]

    path_buf = wintypes.create_unicode_buffer(wintypes.MAX_PATH)
    _SHGetFolderPath(0, CSIDL_COMMON_APPDATA, 0, 0, path_buf)
    return path_buf.value


def _windows_config_path():
    common_data = _windows_commondata_path()
    return _config_path(os.path.join(common_data, 'Datadog'))


def _windows_confd_path():
    common_data = _windows_commondata_path()
    return _confd_path(os.path.join(common_data, 'Datadog'))


def _windows_checksd_path():
    if hasattr(sys, 'frozen'):
        # we're frozen - from py2exe
        prog_path = os.path.dirname(sys.executable)
        return _checksd_path(os.path.join(prog_path, '..'))
    else:
        cur_path = os.path.dirname(__file__)
        return _checksd_path(cur_path)


def _mac_config_path():
    return _config_path(MAC_CONFIG_PATH)


def _mac_confd_path():
    return _confd_path(MAC_CONFIG_PATH)


def _mac_checksd_path():
    return _unix_checksd_path()


def _unix_config_path():
    return _config_path(UNIX_CONFIG_PATH)


def _unix_confd_path():
    return _confd_path(UNIX_CONFIG_PATH)


def _unix_checksd_path():
    # Unix only will look up based on the current directory
    # because checks.d will hang with the other python modules
    cur_path = os.path.dirname(os.path.realpath(__file__))
    return _checksd_path(cur_path)


def _config_path(directory):
    path = os.path.join(directory, DATADOG_CONF)
    if os.path.exists(path):
        return path
    raise PathNotFound(path)


def _confd_path(directory):
    path = os.path.join(directory, 'conf.d')
    if os.path.exists(path):
        return path
    raise PathNotFound(path)


def _checksd_path(directory):
    path = os.path.join(directory, 'checks.d')
    if os.path.exists(path):
        return path
    raise PathNotFound(path)


def _is_affirmative(s):
    # int or real bool
    if isinstance(s, int):
        return bool(s)
    # try string cast
    return s.lower() in ('yes', 'true', '1')


def get_config_path(cfg_path=None, os_name=None):
    # Check if there's an override and if it exists
    if cfg_path is not None and os.path.exists(cfg_path):
        return cfg_path

    # Check if there's a config stored in the current agent directory
    try:
        path = os.path.realpath(__file__)
        path = os.path.dirname(path)
        return _config_path(path)
    except PathNotFound, e:
        pass

    if os_name is None:
        os_name = get_os()

    # Check for an OS-specific path, continue on not-found exceptions
    bad_path = ''
    try:
        if os_name == 'windows':
            return _windows_config_path()
        elif os_name == 'mac':
            return _mac_config_path()
        else:
            return _unix_config_path()
    except PathNotFound, e:
        if len(e.args) > 0:
            bad_path = e.args[0]

    # If all searches fail, exit the agent with an error
    sys.stderr.write("Please supply a configuration file at %s or in the directory where "
                     "the Agent is currently deployed.\n" % bad_path)
    sys.exit(3)


def get_default_bind_host():
    try:
        gethostbyname('localhost')
    except gaierror:
        log.warning("localhost seems undefined in your hosts file, using 127.0.0.1 instead")
        return '127.0.0.1'
    return 'localhost'


def get_histogram_aggregates(configstr=None):
    if configstr is None:
        return None

    try:
        vals = configstr.split(',')
        valid_values = ['min', 'max', 'median', 'avg', 'count']
        result = []

        for val in vals:
            val = val.strip()
            if val not in valid_values:
                log.warning("Ignored histogram aggregate {0}, invalid".format(val))
                continue
            else:
                result.append(val)
    except Exception:
        log.exception("Error when parsing histogram aggregates, skipping")
        return None

    return result


def get_histogram_percentiles(configstr=None):
    if configstr is None:
        return None

    result = []
    try:
        vals = configstr.split(',')
        for val in vals:
            try:
                val = val.strip()
                floatval = float(val)
                if floatval <= 0 or floatval >= 1:
                    raise ValueError
                if len(val) > 4:
                    log.warning("Histogram percentiles are rounded to 2 digits: {0} rounded"
                                .format(floatval))
                result.append(float(val[0:4]))
            except ValueError:
                log.warning("Bad histogram percentile value {0}, must be float in ]0;1[, skipping"
                            .format(val))
    except Exception:
        log.exception("Error when parsing histogram percentiles, skipping")
        return None

    return result


def get_config(parse_args=True, cfg_path=None, options=None):
    if parse_args:
        options, _ = get_parsed_args()

    # General config
    agentConfig = {
        'check_freq': DEFAULT_CHECK_FREQUENCY,
        'dogstatsd_port': 8125,
        'dogstatsd_target': 'http://localhost:17123',
        'graphite_listen_port': None,
        'hostname': None,
        'listen_port': None,
        'tags': None,
        'use_ec2_instance_id': False,  # DEPRECATED
        'version': get_version(),
        'watchdog': True,
        'additional_checksd': '/etc/dd-agent/checks.d/',
        'bind_host': get_default_bind_host(),
        'statsd_metric_namespace': None,
        'utf8_decoding': False
    }

    if Platform.is_mac():
        agentConfig['additional_checksd'] = '/opt/datadog-agent/etc/checks.d'

    # Config handling
    try:
        # Find the right config file
        path = os.path.realpath(__file__)
        path = os.path.dirname(path)

        config_path = get_config_path(cfg_path, os_name=get_os())
        config = ConfigParser.ConfigParser()
        config.readfp(skip_leading_wsp(open(config_path)))

        # bulk import
        for option in config.options('Main'):
            agentConfig[option] = config.get('Main', option)

        # Store developer mode setting in the agentConfig
        if config.has_option('Main', 'developer_mode'):
            agentConfig['developer_mode'] = _is_affirmative(config.get('Main', 'developer_mode'))

        # Allow an override with the --profile option
        if options is not None and options.profile:
            agentConfig['developer_mode'] = True

        #
        # Core config
        #

        # FIXME unnecessarily complex
        agentConfig['use_forwarder'] = False
        if options is not None and options.use_forwarder:
            listen_port = 17123
            if config.has_option('Main', 'listen_port'):
                listen_port = int(config.get('Main', 'listen_port'))
            agentConfig['dd_url'] = "http://" + agentConfig['bind_host'] + ":" + str(listen_port)
            agentConfig['use_forwarder'] = True
        elif options is not None and not options.disable_dd and options.dd_url:
            agentConfig['dd_url'] = options.dd_url
        else:
            agentConfig['dd_url'] = config.get('Main', 'dd_url')
        if agentConfig['dd_url'].endswith('/'):
            agentConfig['dd_url'] = agentConfig['dd_url'][:-1]

        # Extra checks.d path
        # the linux directory is set by default
        if config.has_option('Main', 'additional_checksd'):
            agentConfig['additional_checksd'] = config.get('Main', 'additional_checksd')
        elif get_os() == 'windows':
            # default windows location
            common_path = _windows_commondata_path()
            agentConfig['additional_checksd'] = os.path.join(common_path, 'Datadog', 'checks.d')

        if config.has_option('Main', 'use_dogstatsd'):
            agentConfig['use_dogstatsd'] = config.get('Main', 'use_dogstatsd').lower() in ("yes", "true")
        else:
            agentConfig['use_dogstatsd'] = True

        # Service discovery
        if config.has_option('Main', 'service_discovery_backend'):
            try:
                additional_config = extract_agent_config(config)
                agentConfig.update(additional_config)
            except:
                log.error('Failed to load the agent configuration related to '
                          'service discovery. It will not be used.')

        # Concerns only Windows
        if config.has_option('Main', 'use_web_info_page'):
            agentConfig['use_web_info_page'] = config.get('Main', 'use_web_info_page').lower() in ("yes", "true")
        else:
            agentConfig['use_web_info_page'] = True

        # Which API key to use
        agentConfig['api_key'] = config.get('Main', 'api_key')

        # local traffic only? Default to no
        agentConfig['non_local_traffic'] = False
        if config.has_option('Main', 'non_local_traffic'):
            agentConfig['non_local_traffic'] = config.get('Main', 'non_local_traffic').lower() in ("yes", "true")

        # DEPRECATED
        if config.has_option('Main', 'use_ec2_instance_id'):
            use_ec2_instance_id = config.get('Main', 'use_ec2_instance_id')
            # translate yes into True, the rest into False
            agentConfig['use_ec2_instance_id'] = (use_ec2_instance_id.lower() == 'yes')

        if config.has_option('Main', 'check_freq'):
            try:
                agentConfig['check_freq'] = int(config.get('Main', 'check_freq'))
            except Exception:
                pass

        # Custom histogram aggregate/percentile metrics
        if config.has_option('Main', 'histogram_aggregates'):
            agentConfig['histogram_aggregates'] = get_histogram_aggregates(config.get('Main', 'histogram_aggregates'))

        if config.has_option('Main', 'histogram_percentiles'):
            agentConfig['histogram_percentiles'] = get_histogram_percentiles(config.get('Main', 'histogram_percentiles'))

        # Disable Watchdog (optionally)
        if config.has_option('Main', 'watchdog'):
            if config.get('Main', 'watchdog').lower() in ('no', 'false'):
                agentConfig['watchdog'] = False

        # Optional graphite listener
        if config.has_option('Main', 'graphite_listen_port'):
            agentConfig['graphite_listen_port'] = \
                int(config.get('Main', 'graphite_listen_port'))
        else:
            agentConfig['graphite_listen_port'] = None

        # Dogstatsd config
        dogstatsd_defaults = {
            'dogstatsd_port': 8125,
            'dogstatsd_target': 'http://' + agentConfig['bind_host'] + ':17123',
        }
        for key, value in dogstatsd_defaults.iteritems():
            if config.has_option('Main', key):
                agentConfig[key] = config.get('Main', key)
            else:
                agentConfig[key] = value

        # Create app:xxx tags based on monitored apps
        agentConfig['create_dd_check_tags'] = config.has_option('Main', 'create_dd_check_tags') and \
            _is_affirmative(config.get('Main', 'create_dd_check_tags'))

        # Forwarding to external statsd server
        if config.has_option('Main', 'statsd_forward_host'):
            agentConfig['statsd_forward_host'] = config.get('Main', 'statsd_forward_host')
            if config.has_option('Main', 'statsd_forward_port'):
                agentConfig['statsd_forward_port'] = int(config.get('Main', 'statsd_forward_port'))

        # optionally send dogstatsd data directly to the agent.
        if config.has_option('Main', 'dogstatsd_use_ddurl'):
            if _is_affirmative(config.get('Main', 'dogstatsd_use_ddurl')):
                agentConfig['dogstatsd_target'] = agentConfig['dd_url']

        # Optional config
        # FIXME not the prettiest code ever...
        if config.has_option('Main', 'use_mount'):
            agentConfig['use_mount'] = _is_affirmative(config.get('Main', 'use_mount'))

        if options is not None and options.autorestart:
            agentConfig['autorestart'] = True
        elif config.has_option('Main', 'autorestart'):
            agentConfig['autorestart'] = _is_affirmative(config.get('Main', 'autorestart'))

        if config.has_option('Main', 'check_timings'):
            agentConfig['check_timings'] = _is_affirmative(config.get('Main', 'check_timings'))

        if config.has_option('Main', 'exclude_process_args'):
            agentConfig['exclude_process_args'] = _is_affirmative(config.get('Main', 'exclude_process_args'))

        try:
            filter_device_re = config.get('Main', 'device_blacklist_re')
            agentConfig['device_blacklist_re'] = re.compile(filter_device_re)
        except ConfigParser.NoOptionError:
            pass

        if config.has_option('datadog', 'ddforwarder_log'):
            agentConfig['has_datadog'] = True

        # Dogstream config
        if config.has_option("Main", "dogstream_log"):
            # Older version, single log support
            log_path = config.get("Main", "dogstream_log")
            if config.has_option("Main", "dogstream_line_parser"):
                agentConfig["dogstreams"] = ':'.join([log_path, config.get("Main", "dogstream_line_parser")])
            else:
                agentConfig["dogstreams"] = log_path

        elif config.has_option("Main", "dogstreams"):
            agentConfig["dogstreams"] = config.get("Main", "dogstreams")

        if config.has_option("Main", "nagios_perf_cfg"):
            agentConfig["nagios_perf_cfg"] = config.get("Main", "nagios_perf_cfg")

        if config.has_option("Main", "use_curl_http_client"):
            agentConfig["use_curl_http_client"] = _is_affirmative(config.get("Main", "use_curl_http_client"))
        else:
            # Default to False as there are some issues with the curl client and ELB
            agentConfig["use_curl_http_client"] = False

        if config.has_section('WMI'):
            agentConfig['WMI'] = {}
            for key, value in config.items('WMI'):
                agentConfig['WMI'][key] = value

        if (config.has_option("Main", "limit_memory_consumption") and
                config.get("Main", "limit_memory_consumption") is not None):
            agentConfig["limit_memory_consumption"] = int(config.get("Main", "limit_memory_consumption"))
        else:
            agentConfig["limit_memory_consumption"] = None

        if config.has_option("Main", "skip_ssl_validation"):
            agentConfig["skip_ssl_validation"] = _is_affirmative(config.get("Main", "skip_ssl_validation"))

        agentConfig["collect_instance_metadata"] = True
        if config.has_option("Main", "collect_instance_metadata"):
            agentConfig["collect_instance_metadata"] = _is_affirmative(config.get("Main", "collect_instance_metadata"))

        agentConfig["proxy_forbid_method_switch"] = False
        if config.has_option("Main", "proxy_forbid_method_switch"):
            agentConfig["proxy_forbid_method_switch"] = _is_affirmative(config.get("Main", "proxy_forbid_method_switch"))

        agentConfig["collect_ec2_tags"] = False
        if config.has_option("Main", "collect_ec2_tags"):
            agentConfig["collect_ec2_tags"] = _is_affirmative(config.get("Main", "collect_ec2_tags"))

        agentConfig["utf8_decoding"] = False
        if config.has_option("Main", "utf8_decoding"):
            agentConfig["utf8_decoding"] = _is_affirmative(config.get("Main", "utf8_decoding"))

        agentConfig["gce_updated_hostname"] = False
        if config.has_option("Main", "gce_updated_hostname"):
            agentConfig["gce_updated_hostname"] = _is_affirmative(config.get("Main", "gce_updated_hostname"))

    except ConfigParser.NoSectionError, e:
        sys.stderr.write('Config file not found or incorrectly formatted.\n')
        sys.exit(2)

    except ConfigParser.ParsingError, e:
        sys.stderr.write('Config file not found or incorrectly formatted.\n')
        sys.exit(2)

    except ConfigParser.NoOptionError, e:
        sys.stderr.write('There are some items missing from your config file, but nothing fatal [%s]' % e)

    # Storing proxy settings in the agentConfig
    agentConfig['proxy_settings'] = get_proxy(agentConfig)
    if agentConfig.get('ca_certs', None) is None:
        agentConfig['ssl_certificate'] = get_ssl_certificate(get_os(), 'datadog-cert.pem')
    else:
        agentConfig['ssl_certificate'] = agentConfig['ca_certs']

    return agentConfig


def get_system_stats():
    systemStats = {
        'machine': platform.machine(),
        'platform': sys.platform,
        'processor': platform.processor(),
        'pythonV': platform.python_version(),
    }

    platf = sys.platform

    try:
        if Platform.is_linux(platf):
            output, _, _ = get_subprocess_output(['grep', 'model name', '/proc/cpuinfo'], log)
            systemStats['cpuCores'] = len(output.splitlines())

        if Platform.is_darwin(platf) or Platform.is_freebsd(platf):
            output, _, _ = get_subprocess_output(['sysctl', 'hw.ncpu'], log)
            systemStats['cpuCores'] = int(output.split(': ')[1])
    except SubprocessOutputEmptyError as e:
        log.warning("unable to retrieve number of cpuCores. Failed with error %s", e)

    if Platform.is_linux(platf):
        systemStats['nixV'] = platform.dist()

    elif Platform.is_darwin(platf):
        systemStats['macV'] = platform.mac_ver()

    elif Platform.is_freebsd(platf):
        version = platform.uname()[2]
        systemStats['fbsdV'] = ('freebsd', version, '')  # no codename for FreeBSD

    elif Platform.is_win32(platf):
        systemStats['winV'] = platform.win32_ver()

    return systemStats


def set_win32_cert_path():
    """In order to use tornado.httpclient with the packaged .exe on Windows we
    need to override the default ceritifcate location which is based on the path
    to tornado and will give something like "C:\path\to\program.exe\tornado/cert-file".

    If pull request #379 is accepted (https://github.com/facebook/tornado/pull/379) we
    will be able to override this in a clean way. For now, we have to monkey patch
    tornado.httpclient._DEFAULT_CA_CERTS
    """
    if hasattr(sys, 'frozen'):
        # we're frozen - from py2exe
        prog_path = os.path.dirname(sys.executable)
        crt_path = os.path.join(prog_path, 'ca-certificates.crt')
    else:
        cur_path = os.path.dirname(__file__)
        crt_path = os.path.join(cur_path, 'packaging', 'datadog-agent', 'win32',
                                'install_files', 'ca-certificates.crt')
    import tornado.simple_httpclient
    log.info("Windows certificate path: %s" % crt_path)
    tornado.simple_httpclient._DEFAULT_CA_CERTS = crt_path


def set_win32_requests_ca_bundle_path():
    """In order to allow `requests` to validate SSL requests with the packaged .exe on Windows,
    we need to override the default certificate location which is based on the location of the
    requests or certifi libraries.

    We override the path directly in requests.adapters so that the override works even when the
    `requests` lib has already been imported
    """
    import requests.adapters
    if hasattr(sys, 'frozen'):
        # we're frozen - from py2exe
        prog_path = os.path.dirname(sys.executable)
        ca_bundle_path = os.path.join(prog_path, 'cacert.pem')
        requests.adapters.DEFAULT_CA_BUNDLE_PATH = ca_bundle_path

    log.info("Default CA bundle path of the requests library: {0}"
             .format(requests.adapters.DEFAULT_CA_BUNDLE_PATH))


def get_confd_path(osname=None):
    try:
        cur_path = os.path.dirname(os.path.realpath(__file__))
        return _confd_path(cur_path)
    except PathNotFound, e:
        pass

    if not osname:
        osname = get_os()
    bad_path = ''
    try:
        if osname == 'windows':
            return _windows_confd_path()
        elif osname == 'mac':
            return _mac_confd_path()
        else:
            return _unix_confd_path()
    except PathNotFound, e:
        if len(e.args) > 0:
            bad_path = e.args[0]

    raise PathNotFound(bad_path)


def get_checksd_path(osname=None):
    if not osname:
        osname = get_os()
    if osname == 'windows':
        return _windows_checksd_path()
    elif osname == 'mac':
        return _mac_checksd_path()
    else:
        return _unix_checksd_path()


def get_auto_confd_path(osname=None):
    """Used for service discovery which only works for Unix"""
    return os.path.join(get_confd_path(osname), AUTO_CONFIG_DIR)


def get_win32service_file(osname, filename):
    # This file is needed to log in the event viewer for windows
    if osname == 'windows':
        if hasattr(sys, 'frozen'):
            # we're frozen - from py2exe
            prog_path = os.path.dirname(sys.executable)
            path = os.path.join(prog_path, filename)
        else:
            cur_path = os.path.dirname(__file__)
            path = os.path.join(cur_path, filename)
        if os.path.exists(path):
            log.debug("Certificate file found at %s" % str(path))
            return path

    else:
        cur_path = os.path.dirname(os.path.realpath(__file__))
        path = os.path.join(cur_path, filename)
        if os.path.exists(path):
            return path

    return None


def get_ssl_certificate(osname, filename):
    # The SSL certificate is needed by tornado in case of connection through a proxy
    if osname == 'windows':
        if hasattr(sys, 'frozen'):
            # we're frozen - from py2exe
            prog_path = os.path.dirname(sys.executable)
            path = os.path.join(prog_path, filename)
        else:
            cur_path = os.path.dirname(__file__)
            path = os.path.join(cur_path, filename)
        if os.path.exists(path):
            log.debug("Certificate file found at %s" % str(path))
            return path
    else:
        cur_path = os.path.dirname(os.path.realpath(__file__))
        path = os.path.join(cur_path, filename)
        if os.path.exists(path):
            return path

    log.info("Certificate file NOT found at %s" % str(path))
    return None


def get_checks_paths(agentConfig, osname):
    # this can happen if check.d is not found
    '''Return the checks paths or None if che
    log.error'Checks directory not found, exiting.')cks.d is not found.'''
    checks_paths = [glob.glob(os.path.join(agentConfig['additional_checksd'], '*.py'))]
    try:
        checksd_path = get_checksd_path(osname)
        checks_paths.append(glob.glob(os.path.join(checksd_path, '*.py')))
    except PathNotFound, e:
        log.error(e.args[0])
        return None
    return checks_paths


def get_check_class(check_name, check, init_failed_checks={}):
    '''Return the corresponding check class for a check name if available.'''
    from checks import AgentCheck
    check_class = None
    try:
        check_module = imp.load_source('checksd_%s' % check_name, check)
    except Exception, e:
        traceback_message = traceback.format_exc()
        # There is a configuration file for that check but the module can't be imported
        log.exception('Unable to import check module %s.py from checks.d' % check_name)
        return {'error': e, 'traceback': traceback_message}

    # We make sure that there is an AgentCheck class defined
    check_class = None
    classes = inspect.getmembers(check_module, inspect.isclass)
    for _, clsmember in classes:
        if clsmember == AgentCheck:
            continue
        if issubclass(clsmember, AgentCheck):
            check_class = clsmember
            if AgentCheck in clsmember.__bases__:
                continue
            else:
                break
    return check_class


def load_check_directory(agentConfig, hostname):
    ''' Return the initialized checks from checks.d, and a mapping of checks that failed to
    initialize. Only checks that have a configuration
    file in conf.d will be returned. '''

    from checks import AGENT_METRICS_CHECK_NAME

    initialized_checks = {}
    init_failed_checks = {}
    deprecated_checks = {}
    agentConfig['checksd_hostname'] = hostname

    # the TRACE_CONFIG flag is used by the configcheck to trace config object loading and
    # where they come from (service discovery, auto configuration or configuration file).
    if agentConfig.get(TRACE_CONFIG):
        configs_and_sources = {
            # check_name: (config_source, config)
        }
    deprecated_configs_enabled = [v for k, v in OLD_STYLE_PARAMETERS if len([l for l in agentConfig if l.startswith(k)]) > 0]
    for deprecated_config in deprecated_configs_enabled:
        msg = "Configuring %s in datadog.conf is not supported anymore. Please use conf.d" % deprecated_config
        deprecated_checks[deprecated_config] = {'error': msg, 'traceback': None}
        log.error(msg)

    osname = get_os()
    checks_paths = get_checks_paths(agentConfig, osname)
    # this can happen if check.d is not found
    if checks_paths is None:
        log.error('Check directory not found, exiting. The agent is likely misconfigured.')
        sys.exit(3)

    try:
        confd_path = get_confd_path(osname)
    except PathNotFound, e:
        log.error("No conf.d folder found at '%s' or in the directory where "
                  "the Agent is currently deployed.\n" % e.args[0])
        sys.exit(3)

    if agentConfig.get('service_discovery') and agentConfig.get('service_discovery_backend') in SD_BACKENDS:
        sd_backend = get_sd_backend(agentConfig=agentConfig)
        service_disco_configs = sd_backend.get_configs()
    else:
        service_disco_configs = {}

    # We don't support old style configs anymore
    # So we iterate over the files in the checks.d directory
    # If there is a matching configuration file in the conf.d directory
    # then we import the check
    for check in itertools.chain(*checks_paths):
        sd_init_config, sd_instances, skip_config_lookup = None, None, False
        check_name = os.path.basename(check).split('.')[0]
        check_config = None
        if check_name in initialized_checks or check_name in init_failed_checks:
            log.debug('Skipping check %s because it has already been loaded from another location', check)
            continue

        # Let's see if there is a conf.d for this check
        conf_path = os.path.join(confd_path, '%s.yaml' % check_name)
        conf_exists = False

        if os.path.exists(conf_path):
            conf_exists = True
        else:
            log.debug("No configuration file for %s. Looking for auto config or defaults" % check_name)

            # Default checks read their config from the "[CHECKNAME].yaml.default" file
            default_conf_path = os.path.join(confd_path, '%s.yaml.default' % check_name)
            if not os.path.exists(default_conf_path):
                if check_name not in service_disco_configs:
                    log.debug("Default configuration file {0} is missing. "
                              "Skipping check".format(default_conf_path))
                    continue
                else:
                    # flag set by the configcheck command to track where all configs come from
                    # if it's set, service_disco_configs will look like:
                    # 'check_name': (config_src, (sd_init_config, sd_instances)) instead
                    if agentConfig.get(TRACE_CONFIG):
                        sd_init_config, sd_instances = service_disco_configs[check_name][1]
                        configs_and_sources[check_name] = (
                            service_disco_configs[check_name][0],
                            {'init_config': sd_init_config, 'instances': sd_instances})
                    else:
                        sd_init_config, sd_instances = service_disco_configs[check_name]
                    check_config = {'init_config': sd_init_config, 'instances': sd_instances}
                    skip_config_lookup = True

            else:
                conf_path = default_conf_path
                conf_exists = True

        if not skip_config_lookup:
            if conf_exists:
                try:
                    check_config = check_yaml(conf_path)
                    if agentConfig.get(TRACE_CONFIG):
                        configs_and_sources[check_name] = (CONFIG_FROM_FILE, check_config)
                except Exception, e:
                    log.exception("Unable to parse yaml config in %s" % conf_path)
                    traceback_message = traceback.format_exc()
                    init_failed_checks[check_name] = {'error': str(e), 'traceback': traceback_message}
                    continue
            else:
                # Compatibility code for the Nagios checks if it's still configured
                # in datadog.conf
                # FIXME: 6.x, should be removed
                if check_name == 'nagios':
                    if any([nagios_key in agentConfig for nagios_key in NAGIOS_OLD_CONF_KEYS]):
                        log.warning("Configuring Nagios in datadog.conf is deprecated "
                                    "and will be removed in a future version. "
                                    "Please use conf.d")
                        check_config = {'instances': [dict((key, agentConfig[key]) for key in agentConfig if key in NAGIOS_OLD_CONF_KEYS)]}
                        if agentConfig.get(TRACE_CONFIG):
                            configs_and_sources[check_name] = (CONFIG_FROM_FILE, check_config)
                    else:
                        continue
                else:
                    log.debug("No configuration file for %s" % check_name)
                    continue

        # If we are here, there is a valid matching configuration file.
        # Let's try to import the check
        check_class = get_check_class(check_name, check, init_failed_checks)
        if not check_class:
            log.error('No check class (inheriting from AgentCheck) found in %s.py' % check_name)
            continue
        # this means we are actually looking at a load failure
        elif isinstance(check_class, dict):
            init_failed_checks[check_name] = check_class
        else:
            pass

        # Look for the per-check config, which *must* exist
        if not check_config.get('instances'):
            log.error("Config %s is missing 'instances'" % conf_path)
            continue

        # Init all of the check's classes with
        init_config = check_config.get('init_config', {})
        # init_config: in the configuration triggers init_config to be defined
        # to None.
        if init_config is None:
            init_config = {}

        instances = check_config['instances']
        try:
            try:
                c = check_class(check_name, init_config=init_config,
                                agentConfig=agentConfig, instances=instances)
            except TypeError, e:
                # Backwards compatibility for checks which don't support the
                # instances argument in the constructor.
                c = check_class(check_name, init_config=init_config,
                                agentConfig=agentConfig)
                c.instances = instances
        except Exception, e:
            log.exception('Unable to initialize check %s' % check_name)
            traceback_message = traceback.format_exc()
            init_failed_checks[check_name] = {'error': e, 'traceback': traceback_message}
        else:
            initialized_checks[check_name] = c

        # Add custom pythonpath(s) if available
        if 'pythonpath' in check_config:
            pythonpath = check_config['pythonpath']
            if not isinstance(pythonpath, list):
                pythonpath = [pythonpath]
            sys.path.extend(pythonpath)

        log.debug('Loaded check.d/%s.py' % check_name)

    init_failed_checks.update(deprecated_checks)
    log.info('initialized checks.d checks: %s' % [k for k in initialized_checks.keys() if k != AGENT_METRICS_CHECK_NAME])
    log.info('initialization failed checks.d checks: %s' % init_failed_checks.keys())

    if agentConfig.get(TRACE_CONFIG):
        return configs_and_sources

    return {'initialized_checks': initialized_checks.values(),
            'init_failed_checks': init_failed_checks,
            }


#
# logging

def get_log_date_format():
    return "%Y-%m-%d %H:%M:%S %Z"


def get_log_format(logger_name):
    if get_os() != 'windows':
        return '%%(asctime)s | %%(levelname)s | dd.%s | %%(name)s(%%(filename)s:%%(lineno)s) | %%(message)s' % logger_name
    return '%(asctime)s | %(levelname)s | %(name)s(%(filename)s:%(lineno)s) | %(message)s'


def get_syslog_format(logger_name):
    return 'dd.%s[%%(process)d]: %%(levelname)s (%%(filename)s:%%(lineno)s): %%(message)s' % logger_name


def get_logging_config(cfg_path=None):
    system_os = get_os()
    logging_config = {
        'log_level': None,
        'log_to_event_viewer': False,
        'log_to_syslog': False,
        'syslog_host': None,
        'syslog_port': None,
    }
    if system_os == 'windows':
        logging_config['windows_collector_log_file'] = os.path.join(_windows_commondata_path(), 'Datadog', 'logs', 'collector.log')
        logging_config['windows_forwarder_log_file'] = os.path.join(_windows_commondata_path(), 'Datadog', 'logs', 'forwarder.log')
        logging_config['windows_dogstatsd_log_file'] = os.path.join(_windows_commondata_path(), 'Datadog', 'logs', 'dogstatsd.log')
        logging_config['jmxfetch_log_file'] = os.path.join(_windows_commondata_path(), 'Datadog', 'logs', 'jmxfetch.log')
    else:
        logging_config['collector_log_file'] = '/var/log/datadog/collector.log'
        logging_config['forwarder_log_file'] = '/var/log/datadog/forwarder.log'
        logging_config['dogstatsd_log_file'] = '/var/log/datadog/dogstatsd.log'
        logging_config['jmxfetch_log_file'] = '/var/log/datadog/jmxfetch.log'
        logging_config['go-metro_log_file'] = '/var/log/datadog/go-metro.log'
        logging_config['log_to_syslog'] = True

    config_path = get_config_path(cfg_path, os_name=system_os)
    config = ConfigParser.ConfigParser()
    config.readfp(skip_leading_wsp(open(config_path)))

    if config.has_section('handlers') or config.has_section('loggers') or config.has_section('formatters'):
        if system_os == 'windows':
            config_example_file = "https://github.com/DataDog/dd-agent/blob/master/packaging/datadog-agent/win32/install_files/datadog_win32.conf"
        else:
            config_example_file = "https://github.com/DataDog/dd-agent/blob/master/datadog.conf.example"

        sys.stderr.write("""Python logging config is no longer supported and will be ignored.
            To configure logging, update the logging portion of 'datadog.conf' to match:
             '%s'.
             """ % config_example_file)

    for option in logging_config:
        if config.has_option('Main', option):
            logging_config[option] = config.get('Main', option)

    levels = {
        'CRITICAL': logging.CRITICAL,
        'DEBUG': logging.DEBUG,
        'ERROR': logging.ERROR,
        'FATAL': logging.FATAL,
        'INFO': logging.INFO,
        'WARN': logging.WARN,
        'WARNING': logging.WARNING,
    }
    if config.has_option('Main', 'log_level'):
        logging_config['log_level'] = levels.get(config.get('Main', 'log_level'))

    if config.has_option('Main', 'log_to_syslog'):
        logging_config['log_to_syslog'] = config.get('Main', 'log_to_syslog').strip().lower() in ['yes', 'true', 1]

    if config.has_option('Main', 'log_to_event_viewer'):
        logging_config['log_to_event_viewer'] = config.get('Main', 'log_to_event_viewer').strip().lower() in ['yes', 'true', 1]

    if config.has_option('Main', 'syslog_host'):
        host = config.get('Main', 'syslog_host').strip()
        if host:
            logging_config['syslog_host'] = host
        else:
            logging_config['syslog_host'] = None

    if config.has_option('Main', 'syslog_port'):
        port = config.get('Main', 'syslog_port').strip()
        try:
            logging_config['syslog_port'] = int(port)
        except Exception:
            logging_config['syslog_port'] = None

    if config.has_option('Main', 'disable_file_logging'):
        logging_config['disable_file_logging'] = config.get('Main', 'disable_file_logging').strip().lower() in ['yes', 'true', 1]
    else:
        logging_config['disable_file_logging'] = False

    return logging_config


def initialize_logging(logger_name):
    try:
        logging_config = get_logging_config()

        logging.basicConfig(
            format=get_log_format(logger_name),
            level=logging_config['log_level'] or logging.INFO,
        )

        log_file = logging_config.get('%s_log_file' % logger_name)
        if log_file is not None and not logging_config['disable_file_logging']:
            # make sure the log directory is writeable
            # NOTE: the entire directory needs to be writable so that rotation works
            if os.access(os.path.dirname(log_file), os.R_OK | os.W_OK):
                file_handler = logging.handlers.RotatingFileHandler(log_file, maxBytes=LOGGING_MAX_BYTES, backupCount=1)
                formatter = logging.Formatter(get_log_format(logger_name), get_log_date_format())
                file_handler.setFormatter(formatter)

                root_log = logging.getLogger()
                root_log.addHandler(file_handler)
            else:
                sys.stderr.write("Log file is unwritable: '%s'\n" % log_file)

        # set up syslog
        if logging_config['log_to_syslog']:
            try:
                from logging.handlers import SysLogHandler

                if logging_config['syslog_host'] is not None and logging_config['syslog_port'] is not None:
                    sys_log_addr = (logging_config['syslog_host'], logging_config['syslog_port'])
                else:
                    sys_log_addr = "/dev/log"
                    # Special-case BSDs
                    if Platform.is_darwin():
                        sys_log_addr = "/var/run/syslog"
                    elif Platform.is_freebsd():
                        sys_log_addr = "/var/run/log"

                handler = SysLogHandler(address=sys_log_addr, facility=SysLogHandler.LOG_DAEMON)
                handler.setFormatter(logging.Formatter(get_syslog_format(logger_name), get_log_date_format()))
                root_log = logging.getLogger()
                root_log.addHandler(handler)
            except Exception, e:
                sys.stderr.write("Error setting up syslog: '%s'\n" % str(e))
                traceback.print_exc()

        # Setting up logging in the event viewer for windows
        if get_os() == 'windows' and logging_config['log_to_event_viewer']:
            try:
                from logging.handlers import NTEventLogHandler
                nt_event_handler = NTEventLogHandler(logger_name, get_win32service_file('windows', 'win32service.pyd'), 'Application')
                nt_event_handler.setFormatter(logging.Formatter(get_syslog_format(logger_name), get_log_date_format()))
                nt_event_handler.setLevel(logging.ERROR)
                app_log = logging.getLogger(logger_name)
                app_log.addHandler(nt_event_handler)
            except Exception, e:
                sys.stderr.write("Error setting up Event viewer logging: '%s'\n" % str(e))
                traceback.print_exc()

    except Exception, e:
        sys.stderr.write("Couldn't initialize logging: %s\n" % str(e))
        traceback.print_exc()

        # if config fails entirely, enable basic stdout logging as a fallback
        logging.basicConfig(
            format=get_log_format(logger_name),
            level=logging.INFO,
        )

    # re-get the log after logging is initialized
    global log
    log = logging.getLogger(__name__)