diff --git a/oss_lib/config.py b/oss_lib/config.py
index b3b637d..0ef648e 100644
--- a/oss_lib/config.py
+++ b/oss_lib/config.py
@@ -119,25 +119,43 @@ def register_arguments(parser, service_prefix):
     parser.add_argument(
         "--debug",
         action="store_true",
-        default=False,
-        help="Set the logging level to DEBUG, overrides {0}_DEBUG "
-             "environment variable. (default: false).".format(service_prefix),
+        default=None,
+        help="Sets the logging level to DEBUG, overrides the {0}_DEBUG "
+             "environment variable and configuration "
+             "(possible values: true/false, others - unset)."
+             .format(service_prefix),
+    )
+    parser.add_argument(
+        "--no-debug",
+        action="store_false",
+        dest="debug",
+        default=None,
+        help="Opposite to --debug, disables the debug mode and overrides "
+             "the environment variable and a configuration value.",
     )
     return parser
 
 
+def get_debug_value(env_value):
+    if env_value == "true":
+        return True
+    elif env_value == "false":
+        return False
+    return None
+
+
 def get_env_variables(service_prefix):
-    debug = os.environ.get(service_prefix + "_DEBUG") == "true"
+    debug = os.environ.get(service_prefix + "_DEBUG")
     variables = {
         "config_path": os.environ.get(service_prefix + "_CONF"),
         "log_config_path": os.environ.get(service_prefix + "_LOG_CONF"),
-        "debug": debug,
+        "debug": get_debug_value(debug),
     }
     return variables
 
 
 def setup_config(config_path=None, default_config_path=None, defaults=None,
-                 log_config_path=None, debug=False,
+                 log_config_path=None, debug=None,
                  validation_schema=None):
     global CONF, _CONF
 
@@ -152,10 +170,16 @@ def setup_config(config_path=None, default_config_path=None, defaults=None,
     if loaded_config:
         merge_dicts(config, loaded_config)
 
+    config.setdefault("debug", False)
+    if debug is not None:
+            config["debug"] = debug
+
     if debug:
         log_config(config, config_path, default_config_path)
 
-    validate_config(config, validation_schema)
+    validate_config(config,
+                    defaults=defaults,
+                    validation_schema=validation_schema)
     _CONF = config
     return CONF
 
@@ -214,23 +238,33 @@ def merge_dicts(source, other):
 def log_config(config, config_path, default_config_path):
     LOG.debug("Configuration files: config_path=%s, default_config_path=%s",
               config_path, default_config_path)
-    LOG.debug("Content of the configuration:")
+    LOG.debug("Resulting configuration content:")
     content = io.BytesIO()
     yaml.dump(config, stream=content, default_flow_style=False)
     content.seek(0)
     for line in content:
-        LOG.debug(line)
+        LOG.debug(line.rstrip())
+    LOG.debug("End of resulting configuration content.")
+
+
+def get_required_properties(defaults, schema):
+    if defaults:
+        return list(set(schema.keys()) - set(defaults.keys()))
+    return list(schema.keys())
 
 
-def validate_config(config, validation_schema=None):
+def validate_config(config, defaults=None, validation_schema=None):
     schema = {
         "type": "object",
         "$schema": "http://json-schema.org/draft-04/schema",
-        "properties": {},
+        "properties": {
+            "debug": {"type": "boolean"},
+        },
         "additionalProperties": False,
     }
-    # TODO(akscram): Generate the `required` key based on passed
-    #                defaults and validation_schema properties.
     if validation_schema:
         schema["properties"].update(validation_schema)
+        required = get_required_properties(defaults, validation_schema)
+        if required:
+            schema["required"] = required
     jsonschema.validate(config, schema)
diff --git a/setup.py b/setup.py
index 5f3ef2b..65bcc42 100644
--- a/setup.py
+++ b/setup.py
@@ -2,7 +2,7 @@
 
 setup(
     name="oss_lib",
-    version="0.1.1",
+    version="0.1.2",
     description="OSS Tooling Library",
     license="Apache 2.0",
     url="https://github.com/seecloud/oss-lib",
diff --git a/tests/unit/test_config.py b/tests/unit/test_config.py
index 3cdf293..4ba59f3 100644
--- a/tests/unit/test_config.py
+++ b/tests/unit/test_config.py
@@ -56,7 +56,12 @@ def test_register_arguments(self):
                       help=mock.ANY),
             mock.call("--debug",
                       action="store_true",
-                      default=False,
+                      default=None,
+                      help=mock.ANY),
+            mock.call("--no-debug",
+                      action="store_false",
+                      dest="debug",
+                      default=None,
                       help=mock.ANY),
         ]
 
@@ -77,7 +82,7 @@ def test_register_arguments(self):
     DEFAULT_VARS = {
         "config_path": None,
         "log_config_path": None,
-        "debug": False,
+        "debug": None,
     }
 
     @ddt.data(
@@ -180,11 +185,33 @@ def test_merge_dicts(self, one, other, result):
         config.merge_dicts(one, other)
         assert one == result
 
+    @ddt.data(
+        ({}, {}, []),
+        (None, {}, []),
+        ({}, {"a": {"type": "integer"}}, ["a"]),
+        ({"a": 1}, {"a": {"type": "integer"}}, []),
+        (
+            {"a": 1},
+            {"a": {"type": "integer"}, "b": {"type": "string"}},
+            ["b"],
+        ),
+    )
+    @ddt.unpack
+    def test_get_required_properties(self, defaults, schema, result):
+        value = config.get_required_properties(defaults, schema)
+        assert value == result
+
     @ddt.data(
         ({}, None, False),
         ({"a": 1234}, None, True),
         ({"a": 1234}, {"a": {"type": "integer"}}, False),
         ({"a": 1234}, {"a": {"type": "string"}}, True),
+        ({}, {"b": {"type": "string"}}, True),
+        (
+            {"a": 1234},
+            {"a": {"type": "integer"}, "b": {"type": "string"}},
+            True,
+        ),
     )
     @ddt.unpack
     def test_validate_config(self, conf, schema, error):