diff --git a/home-assistant.conf.default b/home-assistant.conf.default
index 5227d34ef99..fa02152cb83 100644
--- a/home-assistant.conf.default
+++ b/home-assistant.conf.default
@@ -1,20 +1,15 @@
-[common]
+[homeassistant]
 latitude=32.87336
 longitude=-117.22743
 
 [http]
 api_password=mypass
 
-[light.hue]
-host=192.168.1.2
+[light]
+type=hue
 
-[device_tracker.tomato]
-host=192.168.1.1
-username=admin
-password=PASSWORD
-http_id=aaaaaaaaaaaaaaa
-
-[device_tracker.netgear]
+[device_tracker]
+type=netgear
 host=192.168.1.1
 username=admin
 password=PASSWORD
@@ -38,9 +33,9 @@ download_dir=downloads
 
 # A comma seperated list of states that have to be tracked as a single group
 # Grouped states should share the same states (ON/OFF or HOME/NOT_HOME)
-[group]
-living_room=light.Bowl,light.Ceiling,light.TV_back_light
-bedroom=light.Bed_light
+# [group]
+# living_room=light.Bowl,light.Ceiling,light.TV_back_light
+# bedroom=light.Bed_light
 
 [process]
 # items are which processes to look for: <entity_id>=<search string within ps>
diff --git a/homeassistant/__init__.py b/homeassistant/__init__.py
index b7962442501..3509b64c169 100644
--- a/homeassistant/__init__.py
+++ b/homeassistant/__init__.py
@@ -30,6 +30,14 @@ ATTR_NOW = "now"
 ATTR_DOMAIN = "domain"
 ATTR_SERVICE = "service"
 
+CONF_LATITUDE = "latitude"
+CONF_LONGITUDE = "longitude"
+CONF_TYPE = "type"
+CONF_HOST = "host"
+CONF_HOSTS = "hosts"
+CONF_USERNAME = "username"
+CONF_PASSWORD = "password"
+
 # How often time_changed event should fire
 TIMER_INTERVAL = 10  # seconds
 
@@ -334,7 +342,7 @@ class EventBus(object):
 
             for func in listeners:
                 self._pool.add_job(JobPriority.from_event_type(event_type),
-                                  (func, event))
+                                   (func, event))
 
     def listen(self, event_type, listener):
         """ Listen for all events or events of a specific type.
@@ -553,8 +561,8 @@ class ServiceRegistry(object):
                 service_call = ServiceCall(domain, service, service_data)
 
                 self._pool.add_job(JobPriority.EVENT_SERVICE,
-                                  (self._services[domain][service],
-                                   service_call))
+                                   (self._services[domain][service],
+                                    service_call))
 
 
 class Timer(threading.Thread):
diff --git a/homeassistant/bootstrap.py b/homeassistant/bootstrap.py
index 5d089aa31c6..3a54b6f26ab 100644
--- a/homeassistant/bootstrap.py
+++ b/homeassistant/bootstrap.py
@@ -7,20 +7,146 @@ After bootstrapping you can add your own components or
 start by calling homeassistant.start_home_assistant(bus)
 """
 
-import importlib
 import configparser
 import logging
+from collections import defaultdict
+from itertools import chain
 
 import homeassistant
-import homeassistant.components as components
+import homeassistant.components as core_components
+import homeassistant.components.group as group
 
 
-# pylint: disable=too-many-branches,too-many-locals,too-many-statements
-def from_config_file(config_path, enable_logging=True):
-    """ Starts home assistant with all possible functionality
-        based on a config file.
-        Will return a tuple (bus, statemachine). """
+# pylint: disable=too-many-branches
+def from_config_dict(config, hass=None):
+    """
+    Tries to configure Home Assistant from a config dict.
 
+    Dynamically loads required components and its dependencies.
+    """
+    if hass is None:
+        hass = homeassistant.HomeAssistant()
+
+    logger = logging.getLogger(__name__)
+
+    # Make a copy because we are mutating it.
+    # Convert it to defaultdict so components can always have config dict
+    config = defaultdict(dict, config)
+
+    # List of loaded components
+    components = {}
+
+    # List of components to validate
+    to_validate = []
+
+    # List of validated components
+    validated = []
+
+    # List of components we are going to load
+    to_load = [key for key in config.keys() if key != homeassistant.DOMAIN]
+
+    # Load required components
+    while to_load:
+        domain = to_load.pop()
+
+        component = core_components.get_component(domain, logger)
+
+        # if None it does not exist, error already thrown by get_component
+        if component is not None:
+            components[domain] = component
+
+            # Special treatment for GROUP, we want to load it as late as
+            # possible. We do this by loading it if all other to be loaded
+            # modules depend on it.
+            if component.DOMAIN == group.DOMAIN:
+                pass
+
+            # Components with no dependencies are valid
+            elif not component.DEPENDENCIES:
+                validated.append(domain)
+
+            # If dependencies we'll validate it later
+            else:
+                to_validate.append(domain)
+
+                # Make sure to load all dependencies that are not being loaded
+                for dependency in component.DEPENDENCIES:
+                    if dependency not in chain(components.keys(), to_load):
+                        to_load.append(dependency)
+
+    # Validate dependencies
+    group_added = False
+
+    while to_validate:
+        newly_validated = []
+
+        for domain in to_validate:
+            if all(domain in validated for domain
+                   in components[domain].DEPENDENCIES):
+
+                newly_validated.append(domain)
+
+        # We validated new domains this iteration, add them to validated
+        if newly_validated:
+
+            # Add newly validated domains to validated
+            validated.extend(newly_validated)
+
+            # remove domains from to_validate
+            for domain in newly_validated:
+                to_validate.remove(domain)
+
+            newly_validated.clear()
+
+        # Nothing validated this iteration. Add group dependency and try again.
+        elif not group_added:
+            group_added = True
+            validated.append(group.DOMAIN)
+
+        # Group has already been added and we still can't validate all.
+        # Report missing deps as error and skip loading of these domains
+        else:
+            for domain in to_validate:
+                missing_deps = [dep for dep in components[domain].DEPENDENCIES
+                                if dep not in validated]
+
+                logger.error(
+                    "Could not validate all dependencies for {}: {}".format(
+                        domain, ", ".join(missing_deps)))
+
+            break
+
+    # Setup the components
+    if core_components.setup(hass, config):
+        logger.info("Home Assistant core initialized")
+
+        for domain in validated:
+            component = components[domain]
+
+            try:
+                if component.setup(hass, config):
+                    logger.info("component {} initialized".format(domain))
+                else:
+                    logger.error(
+                        "component {} failed to initialize".format(domain))
+
+            except Exception:  # pylint: disable=broad-except
+                logger.exception(
+                    "Error during setup of component {}".format(domain))
+
+    else:
+        logger.error(("Home Assistant core failed to initialize. "
+                      "Further initialization aborted."))
+
+    return hass
+
+
+def from_config_file(config_path, hass=None, enable_logging=True):
+    """
+    Reads the configuration file and tries to start all the required
+    functionality. Will add functionality to 'hass' parameter if given,
+    instantiates a new Home Assistant object if 'hass' is not given.
+    """
     if enable_logging:
         # Setup the logging for home assistant.
         logging.basicConfig(level=logging.INFO)
@@ -34,196 +160,16 @@ def from_config_file(config_path, enable_logging=True):
                               datefmt='%H:%M %d-%m-%y'))
         logging.getLogger('').addHandler(err_handler)
 
-    # Start the actual bootstrapping
-    logger = logging.getLogger(__name__)
-
-    statusses = []
-
     # Read config
     config = configparser.ConfigParser()
     config.read(config_path)
 
-    # Init core
-    hass = homeassistant.HomeAssistant()
+    config_dict = {}
 
-    has_opt = config.has_option
-    get_opt = config.get
-    has_section = config.has_section
-    add_status = lambda name, result: statusses.append((name, result))
-    load_module = lambda module: importlib.import_module(
-        'homeassistant.components.'+module)
+    for section in config.sections():
+        config_dict[section] = {}
 
-    def get_opt_safe(section, option, default=None):
-        """ Failure proof option retriever. """
-        try:
-            return config.get(section, option)
-        except (configparser.NoSectionError, configparser.NoOptionError):
-            return default
+        for key, val in config.items(section):
+            config_dict[section][key] = val
 
-    def get_hosts(section):
-        """ Helper method to retrieve hosts from config. """
-        if has_opt(section, "hosts"):
-            return get_opt(section, "hosts").split(",")
-        else:
-            return None
-
-    # Device scanner
-    dev_scan = None
-
-    try:
-        # For the error message if not all option fields exist
-        opt_fields = "host, username, password"
-
-        if has_section('device_tracker.tomato'):
-            device_tracker = load_module('device_tracker')
-
-            dev_scan_name = "Tomato"
-            opt_fields += ", http_id"
-
-            dev_scan = device_tracker.TomatoDeviceScanner(
-                get_opt('device_tracker.tomato', 'host'),
-                get_opt('device_tracker.tomato', 'username'),
-                get_opt('device_tracker.tomato', 'password'),
-                get_opt('device_tracker.tomato', 'http_id'))
-
-        elif has_section('device_tracker.netgear'):
-            device_tracker = load_module('device_tracker')
-
-            dev_scan_name = "Netgear"
-
-            dev_scan = device_tracker.NetgearDeviceScanner(
-                get_opt('device_tracker.netgear', 'host'),
-                get_opt('device_tracker.netgear', 'username'),
-                get_opt('device_tracker.netgear', 'password'))
-
-        elif has_section('device_tracker.luci'):
-            device_tracker = load_module('device_tracker')
-
-            dev_scan_name = "Luci"
-
-            dev_scan = device_tracker.LuciDeviceScanner(
-                get_opt('device_tracker.luci', 'host'),
-                get_opt('device_tracker.luci', 'username'),
-                get_opt('device_tracker.luci', 'password'))
-
-    except configparser.NoOptionError:
-        # If one of the options didn't exist
-        logger.exception(("Error initializing {}DeviceScanner, "
-                          "could not find one of the following config "
-                          "options: {}".format(dev_scan_name, opt_fields)))
-
-        add_status("Device Scanner - {}".format(dev_scan_name), False)
-
-    if dev_scan:
-        add_status("Device Scanner - {}".format(dev_scan_name),
-                   dev_scan.success_init)
-
-        if not dev_scan.success_init:
-            dev_scan = None
-
-    # Device Tracker
-    if dev_scan:
-        device_tracker.DeviceTracker(hass, dev_scan)
-
-        add_status("Device Tracker", True)
-
-    # Sun tracker
-    if has_opt("common", "latitude") and \
-       has_opt("common", "longitude"):
-
-        sun = load_module('sun')
-
-        add_status("Sun",
-                   sun.setup(hass,
-                             get_opt("common", "latitude"),
-                             get_opt("common", "longitude")))
-    else:
-        sun = None
-
-    # Chromecast
-    if has_section("chromecast"):
-        chromecast = load_module('chromecast')
-
-        hosts = get_hosts("chromecast")
-
-        add_status("Chromecast", chromecast.setup(hass, hosts))
-
-    # WeMo
-    if has_section("wemo"):
-        wemo = load_module('wemo')
-
-        hosts = get_hosts("wemo")
-
-        add_status("WeMo", wemo.setup(hass, hosts))
-
-    # Process tracking
-    if has_section("process"):
-        process = load_module('process')
-
-        processes = dict(config.items('process'))
-        add_status("process", process.setup(hass, processes))
-
-    # Light control
-    if has_section("light.hue"):
-        light = load_module('light')
-
-        light_control = light.HueLightControl(get_opt_safe("hue", "host"))
-
-        add_status("Light - Hue", light_control.success_init)
-
-        if light_control.success_init:
-            light.setup(hass, light_control)
-        else:
-            light_control = None
-
-    else:
-        light_control = None
-
-    if has_opt("downloader", "download_dir"):
-        downloader = load_module('downloader')
-
-        add_status("Downloader", downloader.setup(
-            hass, get_opt("downloader", "download_dir")))
-
-    add_status("Core components", components.setup(hass))
-
-    if has_section('browser'):
-        add_status("Browser", load_module('browser').setup(hass))
-
-    if has_section('keyboard'):
-        add_status("Keyboard", load_module('keyboard').setup(hass))
-
-    # Init HTTP interface
-    if has_opt("http", "api_password"):
-        http = load_module('http')
-
-        http.setup(hass, get_opt("http", "api_password"))
-
-        add_status("HTTP", True)
-
-    # Init groups
-    if has_section("group"):
-        group = load_module('group')
-
-        for name, entity_ids in config.items("group"):
-            add_status("Group - {}".format(name),
-                       group.setup(hass, name, entity_ids.split(",")))
-
-    # Light trigger
-    if light_control and sun:
-        device_sun_light_trigger = load_module('device_sun_light_trigger')
-
-        light_group = get_opt_safe("device_sun_light_trigger", "light_group")
-        light_profile = get_opt_safe("device_sun_light_trigger",
-                                     "light_profile")
-
-        add_status("Device Sun Light Trigger",
-                   device_sun_light_trigger.setup(hass,
-                                                  light_group, light_profile))
-
-    for component, success_init in statusses:
-        status = "initialized" if success_init else "Failed to initialize"
-
-        logger.info("{}: {}".format(component, status))
-
-    return hass
+    return from_config_dict(config_dict, hass)
diff --git a/homeassistant/components/__init__.py b/homeassistant/components/__init__.py
index bb1f78a2d75..165705dc8dd 100644
--- a/homeassistant/components/__init__.py
+++ b/homeassistant/components/__init__.py
@@ -15,6 +15,7 @@ Each component should publish services only under its own domain.
 
 """
 import itertools as it
+import logging
 import importlib
 
 import homeassistant as ha
@@ -44,23 +45,51 @@ SERVICE_MEDIA_NEXT_TRACK = "media_next_track"
 SERVICE_MEDIA_PREV_TRACK = "media_prev_track"
 
 
-def _get_component(component):
-    """ Returns requested component. """
+def get_component(component, logger=None):
+    """ Tries to load specified component.
+        Only returns it if also found to be valid."""
 
     try:
-        return importlib.import_module(
+        comp = importlib.import_module(
             'homeassistant.components.{}'.format(component))
 
     except ImportError:
-        # If we got a bogus component the input will fail
+        if logger:
+            logger.error(
+                "Failed to find component {}".format(component))
+
         return None
 
+    # Validation if component has required methods and attributes
+    errors = []
+
+    if not hasattr(comp, 'DOMAIN'):
+        errors.append("Missing DOMAIN attribute")
+
+    if not hasattr(comp, 'DEPENDENCIES'):
+        errors.append("Missing DEPENDENCIES attribute")
+
+    if not hasattr(comp, 'setup'):
+        errors.append("Missing setup method")
+
+    if errors:
+        if logger:
+            logger.error("Found invalid component {}: {}".format(
+                component, ", ".join(errors)))
+
+        return None
+
+    else:
+        return comp
+
 
 def is_on(hass, entity_id=None):
     """ Loads up the module to call the is_on method.
     If there is no entity id given we will check all. """
+    logger = logging.getLogger(__name__)
+
     if entity_id:
-        group = _get_component('group')
+        group = get_component('group', logger)
 
         entity_ids = group.expand_entity_ids([entity_id])
     else:
@@ -69,7 +98,7 @@ def is_on(hass, entity_id=None):
     for entity_id in entity_ids:
         domain = util.split_entity_id(entity_id)[0]
 
-        module = _get_component(domain)
+        module = get_component(domain, logger)
 
         try:
             if module.is_on(hass, entity_id):
@@ -100,7 +129,7 @@ def extract_entity_ids(hass, service):
     entity_ids = []
 
     if service.data and ATTR_ENTITY_ID in service.data:
-        group = _get_component('group')
+        group = get_component('group')
 
         # Entity ID attr can be a list or a string
         service_ent_id = service.data[ATTR_ENTITY_ID]
@@ -117,7 +146,8 @@ def extract_entity_ids(hass, service):
     return entity_ids
 
 
-def setup(hass):
+# pylint: disable=unused-argument
+def setup(hass, config):
     """ Setup general services related to homeassistant. """
 
     def handle_turn_service(service):
diff --git a/homeassistant/components/browser.py b/homeassistant/components/browser.py
index d1d4272a6a2..556cbd683c9 100644
--- a/homeassistant/components/browser.py
+++ b/homeassistant/components/browser.py
@@ -6,11 +6,13 @@ Provides functionality to launch a webbrowser on the host machine.
 """
 
 DOMAIN = "browser"
+DEPENDENCIES = []
 
 SERVICE_BROWSE_URL = "browse_url"
 
 
-def setup(hass):
+# pylint: disable=unused-argument
+def setup(hass, config):
     """ Listen for browse_url events and open
         the url in the default webbrowser. """
 
diff --git a/homeassistant/components/chromecast.py b/homeassistant/components/chromecast.py
index e60f0596179..b7350a5d981 100644
--- a/homeassistant/components/chromecast.py
+++ b/homeassistant/components/chromecast.py
@@ -10,6 +10,7 @@ import homeassistant.util as util
 import homeassistant.components as components
 
 DOMAIN = 'chromecast'
+DEPENDENCIES = []
 
 SERVICE_YOUTUBE_VIDEO = 'play_youtube_video'
 
@@ -100,7 +101,7 @@ def media_prev_track(hass, entity_id=None):
 
 
 # pylint: disable=too-many-locals, too-many-branches
-def setup(hass, hosts=None):
+def setup(hass, config):
     """ Listen for chromecast events. """
     logger = logging.getLogger(__name__)
 
@@ -113,8 +114,11 @@ def setup(hass, hosts=None):
 
         return False
 
+    if 'hosts' in config[DOMAIN]:
+        hosts = config[DOMAIN]['hosts'].split(",")
+
     # If no hosts given, scan for chromecasts
-    if not hosts:
+    else:
         logger.info("Scanning for Chromecasts")
         hosts = pychromecast.discover_chromecasts()
 
@@ -131,7 +135,7 @@ def setup(hass, hosts=None):
 
             casts[entity_id] = cast
 
-        except pychromecast.ConnectionError:
+        except pychromecast.ChromecastConnectionError:
             pass
 
     if not casts:
diff --git a/homeassistant/components/device_sun_light_trigger.py b/homeassistant/components/device_sun_light_trigger.py
index c7e3cf0172c..99ba0906be5 100644
--- a/homeassistant/components/device_sun_light_trigger.py
+++ b/homeassistant/components/device_sun_light_trigger.py
@@ -11,19 +11,26 @@ from datetime import datetime, timedelta
 import homeassistant.components as components
 from . import light, sun, device_tracker, group
 
+DOMAIN = "device_sun_light_trigger"
+DEPENDENCIES = ['light', 'device_tracker', 'group', 'sun']
 
 LIGHT_TRANSITION_TIME = timedelta(minutes=15)
 
 # Light profile to be used if none given
 LIGHT_PROFILE = 'relax'
 
+CONF_LIGHT_PROFILE = 'light_profile'
+CONF_LIGHT_GROUP = 'light_group'
+
 
 # pylint: disable=too-many-branches
-def setup(hass, light_group=None, light_profile=None):
+def setup(hass, config):
     """ Triggers to turn lights on or off based on device precense. """
 
-    light_group = light_group or light.GROUP_NAME_ALL_LIGHTS
-    light_profile = light_profile or LIGHT_PROFILE
+    light_group = config[DOMAIN].get(CONF_LIGHT_GROUP,
+                                     light.GROUP_NAME_ALL_LIGHTS)
+
+    light_profile = config[DOMAIN].get(CONF_LIGHT_PROFILE, LIGHT_PROFILE)
 
     logger = logging.getLogger(__name__)
 
@@ -61,8 +68,7 @@ def setup(hass, light_group=None, light_profile=None):
         def turn_light_on_before_sunset(light_id):
             """ Helper function to turn on lights slowly if there
                 are devices home and the light is not on yet. """
-            if (device_tracker.is_on(hass) and
-               not light.is_on(hass, light_id)):
+            if device_tracker.is_on(hass) and not light.is_on(hass, light_id):
 
                 light.turn_on(hass, light_id,
                               transition=LIGHT_TRANSITION_TIME.seconds,
@@ -99,8 +105,8 @@ def setup(hass, light_group=None, light_profile=None):
         light_needed = not (lights_are_on or sun.is_on(hass))
 
         # Specific device came home ?
-        if (entity != device_tracker.ENTITY_ID_ALL_DEVICES and
-           new_state.state == components.STATE_HOME):
+        if entity != device_tracker.ENTITY_ID_ALL_DEVICES and \
+           new_state.state == components.STATE_HOME:
 
             # These variables are needed for the elif check
             now = datetime.now()
diff --git a/homeassistant/components/device_tracker.py b/homeassistant/components/device_tracker.py
index 05e8a5e224b..f962c15793c 100644
--- a/homeassistant/components/device_tracker.py
+++ b/homeassistant/components/device_tracker.py
@@ -14,12 +14,14 @@ from datetime import datetime, timedelta
 
 import requests
 
+import homeassistant as ha
 import homeassistant.util as util
 import homeassistant.components as components
 
 from homeassistant.components import group
 
 DOMAIN = "device_tracker"
+DEPENDENCIES = []
 
 SERVICE_DEVICE_TRACKER_RELOAD = "reload_devices_csv"
 
@@ -39,6 +41,8 @@ MIN_TIME_BETWEEN_SCANS = timedelta(seconds=5)
 # Filename to save known devices to
 KNOWN_DEVICES_FILE = "known_devices.csv"
 
+CONF_HTTP_ID = "http_id"
+
 
 def is_on(hass, entity_id=None):
     """ Returns if any or specified device is home. """
@@ -47,16 +51,69 @@ def is_on(hass, entity_id=None):
     return hass.states.is_state(entity, components.STATE_HOME)
 
 
+def setup(hass, config):
+    """ Sets up the device tracker. """
+
+    logger = logging.getLogger(__name__)
+
+    # We have flexible requirements for device tracker so
+    # we cannot use util.validate_config
+
+    conf = config[DOMAIN]
+
+    if not ha.CONF_TYPE in conf:
+        logger.error(
+            'Missing required configuration item in {}: {}'.format(
+                DOMAIN, ha.CONF_TYPE))
+
+        return False
+
+    fields = [ha.CONF_HOST, ha.CONF_USERNAME, ha.CONF_PASSWORD]
+
+    router_type = conf[ha.CONF_TYPE]
+
+    if router_type == 'tomato':
+        fields.append(CONF_HTTP_ID)
+
+        scanner = TomatoDeviceScanner
+
+    elif router_type == 'netgear':
+        scanner = NetgearDeviceScanner
+
+    elif router_type == 'luci':
+        scanner = LuciDeviceScanner
+
+    else:
+        logger.error('Found unknown router type {}'.format(router_type))
+
+        return False
+
+    if not util.validate_config(config, {DOMAIN: fields}, logger):
+        return False
+
+    device_scanner = scanner(conf)
+
+    if not device_scanner.success_init:
+        logger.error(
+            "Failed to initialize device scanner for {}".format(router_type))
+
+        return False
+
+    DeviceTracker(hass, device_scanner)
+
+    return True
+
+
 # pylint: disable=too-many-instance-attributes
 class DeviceTracker(object):
     """ Class that tracks which devices are home and which are not. """
 
-    def __init__(self, hass, device_scanner, error_scanning=None):
+    def __init__(self, hass, device_scanner):
         self.states = hass.states
 
         self.device_scanner = device_scanner
 
-        self.error_scanning = error_scanning or TIME_SPAN_FOR_ERROR_IN_SCANNING
+        self.error_scanning = TIME_SPAN_FOR_ERROR_IN_SCANNING
 
         self.logger = logging.getLogger(__name__)
 
@@ -84,7 +141,7 @@ class DeviceTracker(object):
 
         self.update_devices()
 
-        group.setup(hass, GROUP_NAME_ALL_DEVICES, self.device_entity_ids)
+        group.setup_group(hass, GROUP_NAME_ALL_DEVICES, self.device_entity_ids)
 
     @property
     def device_entity_ids(self):
@@ -164,8 +221,8 @@ class DeviceTracker(object):
                 except IOError:
                     self.logger.exception((
                         "DeviceTracker:Error updating {}"
-                        "with {} new devices").format(
-                        KNOWN_DEVICES_FILE, len(unknown_devices)))
+                        "with {} new devices").format(KNOWN_DEVICES_FILE,
+                                                      len(unknown_devices)))
 
         self.lock.release()
 
@@ -223,8 +280,8 @@ class DeviceTracker(object):
 
                     # Remove entities that are no longer maintained
                     new_entity_ids = set([known_devices[device]['entity_id']
-                                         for device in known_devices
-                                         if known_devices[device]['track']])
+                                          for device in known_devices
+                                          if known_devices[device]['track']])
 
                     for entity_id in \
                             self.device_entity_ids - new_entity_ids:
@@ -246,8 +303,8 @@ class DeviceTracker(object):
                     self.invalid_known_devices_file = True
                     self.logger.warning((
                         "Invalid {} found. "
-                        "We won't update it with new found devices.").
-                        format(KNOWN_DEVICES_FILE))
+                        "We won't update it with new found devices."
+                        ).format(KNOWN_DEVICES_FILE))
 
                 finally:
                     self.lock.release()
@@ -261,7 +318,10 @@ class TomatoDeviceScanner(object):
     http://paulusschoutsen.nl/blog/2013/10/tomato-api-documentation/
     """
 
-    def __init__(self, host, username, password, http_id):
+    def __init__(self, config):
+        host, http_id = config['host'], config['http_id']
+        username, password = config['username'], config['password']
+
         self.req = requests.Request('POST',
                                     'http://{}/update.cgi'.format(host),
                                     data={'_http_id': http_id,
@@ -309,8 +369,8 @@ class TomatoDeviceScanner(object):
         self.lock.acquire()
 
         # if date_updated is None or the date is too old we scan for new data
-        if (not self.date_updated or datetime.now() - self.date_updated >
-           MIN_TIME_BETWEEN_SCANS):
+        if not self.date_updated or \
+           datetime.now() - self.date_updated > MIN_TIME_BETWEEN_SCANS:
 
             self.logger.info("Tomato:Scanning")
 
@@ -380,7 +440,10 @@ class TomatoDeviceScanner(object):
 class NetgearDeviceScanner(object):
     """ This class queries a Netgear wireless router using the SOAP-api. """
 
-    def __init__(self, host, username, password):
+    def __init__(self, config):
+        host = config['host']
+        username, password = config['username'], config['password']
+
         self.logger = logging.getLogger(__name__)
         self.date_updated = None
         self.last_results = []
@@ -442,8 +505,8 @@ class NetgearDeviceScanner(object):
         with self.lock:
             # if date_updated is None or the date is too old we scan for
             # new data
-            if (not self.date_updated or datetime.now() - self.date_updated >
-               MIN_TIME_BETWEEN_SCANS):
+            if not self.date_updated or \
+               datetime.now() - self.date_updated > MIN_TIME_BETWEEN_SCANS:
 
                 self.logger.info("Netgear:Scanning")
 
@@ -470,7 +533,10 @@ class LuciDeviceScanner(object):
     (Currently, we do only wifi iwscan, and no DHCP lease access.)
     """
 
-    def __init__(self, host, username, password):
+    def __init__(self, config):
+        host = config['host']
+        username, password = config['username'], config['password']
+
         self.parse_api_pattern = re.compile(r"(?P<param>\w*) = (?P<value>.*);")
 
         self.logger = logging.getLogger(__name__)
@@ -554,8 +620,8 @@ class LuciDeviceScanner(object):
         with self.lock:
             # if date_updated is None or the date is too old we scan
             # for new data
-            if (not self.date_updated or datetime.now() - self.date_updated >
-               MIN_TIME_BETWEEN_SCANS):
+            if not self.date_updated or \
+               datetime.now() - self.date_updated > MIN_TIME_BETWEEN_SCANS:
 
                 self.logger.info("Checking ARP")
 
diff --git a/homeassistant/components/downloader.py b/homeassistant/components/downloader.py
index 1f109ec8b7f..1f979063a4a 100644
--- a/homeassistant/components/downloader.py
+++ b/homeassistant/components/downloader.py
@@ -12,15 +12,18 @@ import threading
 import homeassistant.util as util
 
 DOMAIN = "downloader"
+DEPENDENCIES = []
 
 SERVICE_DOWNLOAD_FILE = "download_file"
 
 ATTR_URL = "url"
 ATTR_SUBDIR = "subdir"
 
+CONF_DOWNLOAD_DIR = 'download_dir'
+
 
 # pylint: disable=too-many-branches
-def setup(hass, download_path):
+def setup(hass, config):
     """ Listens for download events to download files. """
 
     logger = logging.getLogger(__name__)
@@ -33,6 +36,11 @@ def setup(hass, download_path):
 
         return False
 
+    if not util.validate_config(config, {DOMAIN: [CONF_DOWNLOAD_DIR]}, logger):
+        return False
+
+    download_path = config[DOMAIN][CONF_DOWNLOAD_DIR]
+
     if not os.path.isdir(download_path):
 
         logger.error(
@@ -106,8 +114,7 @@ def setup(hass, download_path):
 
                         final_path = "{}_{}.{}".format(path, tries, ext)
 
-                    logger.info("{} -> {}".format(
-                                url, final_path))
+                    logger.info("{} -> {}".format(url, final_path))
 
                     with open(final_path, 'wb') as fil:
                         for chunk in req.iter_content(1024):
diff --git a/homeassistant/components/group.py b/homeassistant/components/group.py
index 9b8d989b78b..0bf336c8e1d 100644
--- a/homeassistant/components/group.py
+++ b/homeassistant/components/group.py
@@ -13,6 +13,7 @@ from homeassistant.components import (STATE_ON, STATE_OFF,
                                       ATTR_ENTITY_ID)
 
 DOMAIN = "group"
+DEPENDENCIES = []
 
 ENTITY_ID_FORMAT = DOMAIN + ".{}"
 
@@ -89,13 +90,21 @@ def get_entity_ids(hass, entity_id, domain_filter=None):
 
 
 # pylint: disable=too-many-branches, too-many-locals
-def setup(hass, name, entity_ids):
+def setup(hass, config):
+    """ Sets up all groups found definded in the configuration. """
+
+    for name, entity_ids in config[DOMAIN].items():
+        entity_ids = entity_ids.split(",")
+
+        setup_group(hass, name, entity_ids)
+
+    return True
+
+
+def setup_group(hass, name, entity_ids):
     """ Sets up a group state that is the combined state of
         several states. Supports ON/OFF and DEVICE_HOME/DEVICE_NOT_HOME. """
 
-    # Convert entity_ids to a list incase it is an iterable
-    entity_ids = list(entity_ids)
-
     logger = logging.getLogger(__name__)
 
     # Loop over the given entities to:
@@ -118,9 +127,11 @@ def setup(hass, name, entity_ids):
 
             else:
                 # We did not find a matching group_type
-                errors.append("Found unexpected state '{}'".format(
-                              name, state.state))
+                errors.append(
+                    "Entity {} has ungroupable state '{}'".format(
+                        name, state.state))
 
+                # Stop check all other entity IDs and report as error
                 break
 
         # Check if entity exists
@@ -134,43 +145,48 @@ def setup(hass, name, entity_ids):
                 entity_id, state.state, group_off, group_on))
 
         # Keep track of the group state to init later on
-        elif group_state == group_off and state.state == group_on:
+        elif state.state == group_on:
             group_state = group_on
 
+    if group_type is None and not errors:
+        errors.append('Unable to determine group type for {}'.format(name))
+
     if errors:
-        logger.error("Error setting up state group {}: {}".format(
+        logger.error("Error setting up group {}: {}".format(
             name, ", ".join(errors)))
 
         return False
 
-    group_entity_id = ENTITY_ID_FORMAT.format(name)
-    state_attr = {ATTR_ENTITY_ID: entity_ids}
+    else:
+        group_entity_id = ENTITY_ID_FORMAT.format(name)
+        state_attr = {ATTR_ENTITY_ID: entity_ids}
 
-    # pylint: disable=unused-argument
-    def update_group_state(entity_id, old_state, new_state):
-        """ Updates the group state based on a state change by a tracked
-            entity. """
+        # pylint: disable=unused-argument
+        def update_group_state(entity_id, old_state, new_state):
+            """ Updates the group state based on a state change by
+                a tracked entity. """
 
-        cur_group_state = hass.states.get(group_entity_id).state
+            cur_gr_state = hass.states.get(group_entity_id).state
 
-        # if cur_group_state = OFF and new_state = ON: set ON
-        # if cur_group_state = ON and new_state = OFF: research
-        # else: ignore
+            # if cur_gr_state = OFF and new_state = ON: set ON
+            # if cur_gr_state = ON and new_state = OFF: research
+            # else: ignore
 
-        if cur_group_state == group_off and new_state.state == group_on:
+            if cur_gr_state == group_off and new_state.state == group_on:
 
-            hass.states.set(group_entity_id, group_on, state_attr)
+                hass.states.set(group_entity_id, group_on, state_attr)
 
-        elif cur_group_state == group_on and new_state.state == group_off:
+            elif cur_gr_state == group_on and new_state.state == group_off:
 
-            # Check if any of the other states is still on
-            if not any([hass.states.is_state(ent_id, group_on)
-                        for ent_id in entity_ids if entity_id != ent_id]):
-                hass.states.set(group_entity_id, group_off, state_attr)
+                # Check if any of the other states is still on
+                if not any([hass.states.is_state(ent_id, group_on)
+                            for ent_id in entity_ids
+                            if entity_id != ent_id]):
+                    hass.states.set(group_entity_id, group_off, state_attr)
 
-    for entity_id in entity_ids:
-        hass.track_state_change(entity_id, update_group_state)
+        for entity_id in entity_ids:
+            hass.track_state_change(entity_id, update_group_state)
 
-    hass.states.set(group_entity_id, group_state, state_attr)
+        hass.states.set(group_entity_id, group_state, state_attr)
 
-    return True
+        return True
diff --git a/homeassistant/components/http/__init__.py b/homeassistant/components/http/__init__.py
index df0c38890b2..362e9cdb0d9 100644
--- a/homeassistant/components/http/__init__.py
+++ b/homeassistant/components/http/__init__.py
@@ -89,6 +89,8 @@ import homeassistant.remote as rem
 import homeassistant.util as util
 from homeassistant.components import (STATE_ON, STATE_OFF,
                                       SERVICE_TURN_ON, SERVICE_TURN_OFF)
+DOMAIN = "http"
+DEPENDENCIES = []
 
 HTTP_OK = 200
 HTTP_CREATED = 201
@@ -120,6 +122,10 @@ DOMAIN_ICONS = {
     "downloader": "glyphicon-download-alt"
 }
 
+CONF_API_PASSWORD = "api_password"
+CONF_SERVER_HOST = "server_host"
+CONF_SERVER_PORT = "server_port"
+
 
 def _get_domain_icon(domain):
     """ Returns HTML that shows domain icon. """
@@ -127,12 +133,19 @@ def _get_domain_icon(domain):
         DOMAIN_ICONS.get(domain, ""))
 
 
-def setup(hass, api_password, server_port=None, server_host=None):
+def setup(hass, config):
     """ Sets up the HTTP API and debug interface. """
-    server_port = server_port or rem.SERVER_PORT
+
+    if not util.validate_config(config, {DOMAIN: [CONF_API_PASSWORD]},
+                                logging.getLogger(__name__)):
+        return False
+
+    api_password = config[DOMAIN]['api_password']
 
     # If no server host is given, accept all incoming requests
-    server_host = server_host or '0.0.0.0'
+    server_host = config[DOMAIN].get(CONF_SERVER_HOST, '0.0.0.0')
+
+    server_port = config[DOMAIN].get(CONF_SERVER_PORT, rem.SERVER_PORT)
 
     server = HomeAssistantHTTPServer((server_host, server_port),
                                      RequestHandler, hass, api_password)
@@ -147,6 +160,8 @@ def setup(hass, api_password, server_port=None, server_host=None):
         hass.local_api = \
             rem.API(util.get_local_ip(), api_password, server_port)
 
+    return True
+
 
 class HomeAssistantHTTPServer(ThreadingMixIn, HTTPServer):
     """ Handle HTTP requests in a threaded fashion. """
@@ -213,7 +228,7 @@ class RequestHandler(BaseHTTPRequestHandler):
         # /event_forwarding
         ('POST', rem.URL_API_EVENT_FORWARD, '_handle_post_api_event_forward'),
         ('DELETE', rem.URL_API_EVENT_FORWARD,
-            '_handle_delete_api_event_forward'),
+         '_handle_delete_api_event_forward'),
 
         # Statis files
         ('GET', re.compile(r'/static/(?P<file>[a-zA-Z\._\-0-9/]+)'),
@@ -407,7 +422,7 @@ class RequestHandler(BaseHTTPRequestHandler):
                        "href='#'></a>").format(action, state.entity_id))
 
             write("</td><td>{}</td><td>{}</td></tr>".format(
-                  attributes, util.datetime_to_str(state.last_changed)))
+                attributes, util.datetime_to_str(state.last_changed)))
 
         # Change state form
         write(("<tr><td></td><td><input name='entity_id' class='form-control' "
diff --git a/homeassistant/components/keyboard.py b/homeassistant/components/keyboard.py
index 2b261a4fc56..40d4b938e47 100644
--- a/homeassistant/components/keyboard.py
+++ b/homeassistant/components/keyboard.py
@@ -9,6 +9,7 @@ import logging
 import homeassistant.components as components
 
 DOMAIN = "keyboard"
+DEPENDENCIES = []
 
 
 def volume_up(hass):
@@ -41,13 +42,14 @@ def media_prev_track(hass):
     hass.call_service(DOMAIN, components.SERVICE_MEDIA_PREV_TRACK)
 
 
-def setup(hass):
+# pylint: disable=unused-argument
+def setup(hass, config):
     """ Listen for keyboard events. """
     try:
         import pykeyboard
     except ImportError:
         logging.getLogger(__name__).exception(
-            "MediaButtons: Error while importing dependency PyUserInput.")
+            "Error while importing dependency PyUserInput.")
 
         return False
 
diff --git a/homeassistant/components/light/__init__.py b/homeassistant/components/light/__init__.py
index c15116c4d68..aabb2b98d2f 100644
--- a/homeassistant/components/light/__init__.py
+++ b/homeassistant/components/light/__init__.py
@@ -55,6 +55,7 @@ from collections import namedtuple
 import os
 import csv
 
+import homeassistant as ha
 import homeassistant.util as util
 from homeassistant.components import (group, extract_entity_ids,
                                       STATE_ON, STATE_OFF,
@@ -63,6 +64,7 @@ from homeassistant.components import (group, extract_entity_ids,
 
 
 DOMAIN = "light"
+DEPENDENCIES = []
 
 GROUP_NAME_ALL_LIGHTS = 'all_lights'
 ENTITY_ID_ALL_LIGHTS = group.ENTITY_ID_FORMAT.format(
@@ -136,11 +138,26 @@ def turn_off(hass, entity_id=None, transition=None):
 
 
 # pylint: disable=too-many-branches, too-many-locals
-def setup(hass, light_control):
+def setup(hass, config):
     """ Exposes light control via statemachine and services. """
 
     logger = logging.getLogger(__name__)
 
+    if not util.validate_config(config, {DOMAIN: [ha.CONF_TYPE]}, logger):
+        return False
+
+    light_type = config[DOMAIN][ha.CONF_TYPE]
+
+    if light_type == 'hue':
+        light_init = HueLightControl
+
+    else:
+        logger.error("Found unknown light type: {}".format(light_type))
+
+        return False
+
+    light_control = light_init(config[DOMAIN])
+
     ent_to_light = {}
     light_to_ent = {}
 
@@ -188,9 +205,9 @@ def setup(hass, light_control):
         """ Update the state of all the lights. """
 
         # First time this method gets called, force_reload should be True
-        if (force_reload or
-           datetime.now() - update_lights_state.last_updated >
-           MIN_TIME_BETWEEN_SCANS):
+        if force_reload or \
+           datetime.now() - update_lights_state.last_updated > \
+           MIN_TIME_BETWEEN_SCANS:
 
             logger.info("Updating light status")
             update_lights_state.last_updated = datetime.now()
@@ -206,7 +223,7 @@ def setup(hass, light_control):
         return False
 
     # Track all lights in a group
-    group.setup(hass, GROUP_NAME_ALL_LIGHTS, light_to_ent.values())
+    group.setup_group(hass, GROUP_NAME_ALL_LIGHTS, light_to_ent.values())
 
     # Load built-in profiles and custom profiles
     profile_paths = [os.path.dirname(__file__), os.getcwd()]
@@ -336,9 +353,11 @@ def _hue_to_light_state(info):
 class HueLightControl(object):
     """ Class to interface with the Hue light system. """
 
-    def __init__(self, host=None):
+    def __init__(self, config):
         logger = logging.getLogger(__name__)
 
+        host = config.get(ha.CONF_HOST, None)
+
         try:
             import phue
         except ImportError:
diff --git a/homeassistant/components/process.py b/homeassistant/components/process.py
index 1a88bc6b699..7b57f4a626d 100644
--- a/homeassistant/components/process.py
+++ b/homeassistant/components/process.py
@@ -26,12 +26,13 @@ from homeassistant.components import STATE_ON, STATE_OFF
 import homeassistant.util as util
 
 DOMAIN = 'process'
+DEPENDENCIES = []
 ENTITY_ID_FORMAT = DOMAIN + '.{}'
 
 PS_STRING = 'ps awx'
 
 
-def setup(hass, processes):
+def setup(hass, config):
     """ Sets up a check if specified processes are running.
 
         processes: dict mapping entity id to substring to search for
@@ -39,7 +40,7 @@ def setup(hass, processes):
     """
 
     entities = {ENTITY_ID_FORMAT.format(util.slugify(pname)): pstring
-                for pname, pstring in processes.items()}
+                for pname, pstring in config[DOMAIN].items()}
 
     # pylint: disable=unused-argument
     def update_process_states(time):
diff --git a/homeassistant/components/sun.py b/homeassistant/components/sun.py
index c728ce39d81..5b775695cdf 100644
--- a/homeassistant/components/sun.py
+++ b/homeassistant/components/sun.py
@@ -7,8 +7,11 @@ Provides functionality to keep track of the sun.
 import logging
 from datetime import timedelta
 
+import homeassistant as ha
 import homeassistant.util as util
 
+DEPENDENCIES = []
+DOMAIN = "sun"
 ENTITY_ID = "sun.sun"
 
 STATE_ABOVE_HORIZON = "above_horizon"
@@ -49,10 +52,16 @@ def next_rising(hass):
         return None
 
 
-def setup(hass, latitude, longitude):
+def setup(hass, config):
     """ Tracks the state of the sun. """
     logger = logging.getLogger(__name__)
 
+    if not util.validate_config(config,
+                                {ha.DOMAIN: [ha.CONF_LATITUDE,
+                                             ha.CONF_LONGITUDE]},
+                                logger):
+        return False
+
     try:
         import ephem
     except ImportError:
@@ -61,12 +70,15 @@ def setup(hass, latitude, longitude):
 
     sun = ephem.Sun()  # pylint: disable=no-member
 
+    latitude = config[ha.DOMAIN][ha.CONF_LATITUDE]
+    longitude = config[ha.DOMAIN][ha.CONF_LONGITUDE]
+
     def update_sun_state(now):    # pylint: disable=unused-argument
         """ Method to update the current state of the sun and
             set time of next setting and rising. """
         observer = ephem.Observer()
-        observer.lat = latitude
-        observer.long = longitude
+        observer.lat = latitude  # pylint: disable=assigning-non-slot
+        observer.long = longitude  # pylint: disable=assigning-non-slot
 
         next_rising_dt = ephem.localtime(observer.next_rising(sun))
         next_setting_dt = ephem.localtime(observer.next_setting(sun))
diff --git a/homeassistant/components/wemo.py b/homeassistant/components/wemo.py
index 1892db66fdf..521c8d8559c 100644
--- a/homeassistant/components/wemo.py
+++ b/homeassistant/components/wemo.py
@@ -4,12 +4,14 @@ Component to interface with WeMo devices on the network.
 import logging
 from datetime import datetime, timedelta
 
+import homeassistant as ha
 import homeassistant.util as util
 from homeassistant.components import (group, extract_entity_ids,
                                       STATE_ON, STATE_OFF,
                                       SERVICE_TURN_ON, SERVICE_TURN_OFF,
                                       ATTR_ENTITY_ID, ATTR_FRIENDLY_NAME)
 DOMAIN = 'wemo'
+DEPENDENCIES = []
 
 GROUP_NAME_ALL_WEMOS = 'all_wemos'
 ENTITY_ID_ALL_WEMOS = group.ENTITY_ID_FORMAT.format(
@@ -47,7 +49,7 @@ def turn_off(hass, entity_id=None):
 
 
 # pylint: disable=too-many-branches
-def setup(hass, hosts=None):
+def setup(hass, config):
     """ Track states and offer events for WeMo switches. """
     logger = logging.getLogger(__name__)
 
@@ -61,10 +63,10 @@ def setup(hass, hosts=None):
 
         return False
 
-    if hosts:
+    if ha.CONF_HOSTS in config[DOMAIN]:
         devices = []
 
-        for host in hosts:
+        for host in config[DOMAIN][ha.CONF_HOSTS].split(","):
             device = pywemo.device_from_host(host)
 
             if device:
@@ -125,9 +127,9 @@ def setup(hass, hosts=None):
         """ Update states of all WeMo devices. """
 
         # First time this method gets called, force_reload should be True
-        if (force_reload or
-           datetime.now() - update_wemos_state.last_updated >
-           MIN_TIME_BETWEEN_SCANS):
+        if force_reload or \
+           datetime.now() - update_wemos_state.last_updated > \
+           MIN_TIME_BETWEEN_SCANS:
 
             logger.info("Updating WeMo status")
             update_wemos_state.last_updated = datetime.now()
@@ -138,7 +140,7 @@ def setup(hass, hosts=None):
     update_wemos_state(None, True)
 
     # Track all lights in a group
-    group.setup(hass, GROUP_NAME_ALL_WEMOS, sno_to_ent.values())
+    group.setup_group(hass, GROUP_NAME_ALL_WEMOS, sno_to_ent.values())
 
     def handle_wemo_service(service):
         """ Handles calls to the WeMo service. """
diff --git a/homeassistant/remote.py b/homeassistant/remote.py
index 7bf53e37281..39ce4a26203 100644
--- a/homeassistant/remote.py
+++ b/homeassistant/remote.py
@@ -95,7 +95,8 @@ class HomeAssistant(ha.HomeAssistant):
     def __init__(self, remote_api, local_api=None):
         if not remote_api.validate_api():
             raise ha.HomeAssistantError(
-                "Remote API not valid: {}".format(remote_api.status))
+                "Remote API at {}:{} not valid: {}".format(
+                    remote_api.host, remote_api.port, remote_api.status))
 
         self.remote_api = remote_api
         self.local_api = local_api
@@ -113,7 +114,10 @@ class HomeAssistant(ha.HomeAssistant):
             import homeassistant.components.http as http
             import random
 
-            http.setup(self, '%030x'.format(random.randrange(16**30)))
+            # pylint: disable=too-many-format-args
+            random_password = '%030x'.format(random.randrange(16**30))
+
+            http.setup(self, random_password)
 
         ha.Timer(self)
 
diff --git a/homeassistant/test.py b/homeassistant/test.py
index b61b17f32d2..e42fdac6759 100644
--- a/homeassistant/test.py
+++ b/homeassistant/test.py
@@ -40,7 +40,8 @@ def ensure_homeassistant_started():
         hass.bus.listen('test_event', len)
         hass.states.set('test', 'a_state')
 
-        http.setup(hass, API_PASSWORD)
+        http.setup(hass,
+                   {http.DOMAIN: {http.CONF_API_PASSWORD: API_PASSWORD}})
 
         hass.start()
 
@@ -55,12 +56,16 @@ def ensure_homeassistant_started():
 def ensure_slave_started():
     """ Ensure a home assistant slave is started. """
 
+    ensure_homeassistant_started()
+
     if not HAHelper.slave:
         local_api = remote.API("127.0.0.1", API_PASSWORD, 8124)
         remote_api = remote.API("127.0.0.1", API_PASSWORD)
-        slave = remote.HomeAssistant(local_api, remote_api)
+        slave = remote.HomeAssistant(remote_api, local_api)
 
-        http.setup(slave, API_PASSWORD, 8124)
+        http.setup(slave,
+                   {http.DOMAIN: {http.CONF_API_PASSWORD: API_PASSWORD,
+                                  http.CONF_SERVER_PORT: 8124}})
 
         slave.start()
 
@@ -73,7 +78,7 @@ def ensure_slave_started():
 
 
 # pylint: disable=too-many-public-methods
-class TestHTTPInterface(unittest.TestCase):
+class TestHTTP(unittest.TestCase):
     """ Test the HTTP debug interface and API. """
 
     @classmethod
diff --git a/homeassistant/util.py b/homeassistant/util.py
index b28c20ebbb9..2de31ce12dc 100644
--- a/homeassistant/util.py
+++ b/homeassistant/util.py
@@ -167,6 +167,30 @@ class OrderedEnum(enum.Enum):
         return NotImplemented
 
 
+def validate_config(config, items, logger):
+    """
+    Validates if all items are available in the configuration.
+
+    config is the general dictionary with all the configurations.
+    items is a dict with per domain which attributes we require.
+    logger is the logger from the caller to log the errors to.
+
+    Returns True if all required items were found.
+    """
+    errors_found = False
+    for domain in items.keys():
+        errors = [item for item in items[domain] if item not in config[domain]]
+
+        if errors:
+            logger.error(
+                "Missing required configuration items in {}: {}".format(
+                    domain, ", ".join(errors)))
+
+            errors_found = True
+
+    return not errors_found
+
+
 # Reason why I decided to roll my own ThreadPool instead of using
 # multiprocessing.dummy.pool or even better, use multiprocessing.pool and
 # not be hurt by the GIL in the cpython interpreter: