Setting app.debug does not propagate to app.log logger log level
In https://github.com/awslabs/chalice/blob/master/chalice/app.py#L434-L437, intent is shown to set the logger's log level according to the value of Chalice.debug. However, app.debug is currently hardcoded to false in `Chalice.__init__`, so without calling `Chalice. _configure_logging()` again or setting it manually via `app.log.setLevel(logging.DEBUG)`, it will always remain set to logging.ERROR.

It would probably make more sense to have a `Chalice.debug` setter that also sets the logger's level, and/or have a `Chalice(debug=True)` kwarg to make the code linked above behave as expected.
diff --git a/chalice/app.py b/chalice/app.py
index 8efbdf0..691f08a 100644
--- a/chalice/app.py
+++ b/chalice/app.py
@@ -418,12 +418,12 @@ class Chalice(object):
 
     FORMAT_STRING = '%(name)s - %(levelname)s - %(message)s'
 
-    def __init__(self, app_name, configure_logs=True, env=None):
+    def __init__(self, app_name, debug=False, configure_logs=True, env=None):
         self.app_name = app_name
         self.api = APIGateway()
         self.routes = defaultdict(dict)
         self.current_request = None
-        self.debug = False
+        self._debug = debug
         self.configure_logs = configure_logs
         self.log = logging.getLogger(self.app_name)
         self.builtin_auth_handlers = []
@@ -441,22 +441,26 @@ class Chalice(object):
             __version__,
         )
 
+    @property
+    def debug(self):
+        return self._debug
+
+    @debug.setter
+    def debug(self, value):
+        self._debug = value
+        self._configure_log_level()
+
     def _configure_logging(self):
-        log = logging.getLogger(self.app_name)
-        if self._already_configured(log):
+        if self._already_configured(self.log):
             return
         handler = logging.StreamHandler(sys.stdout)
         # Timestamp is handled by lambda itself so the
         # default FORMAT_STRING doesn't need to include it.
         formatter = logging.Formatter(self.FORMAT_STRING)
         handler.setFormatter(formatter)
-        log.propagate = False
-        if self.debug:
-            level = logging.DEBUG
-        else:
-            level = logging.ERROR
-        log.setLevel(level)
-        log.addHandler(handler)
+        self.log.propagate = False
+        self._configure_log_level()
+        self.log.addHandler(handler)
 
     def _already_configured(self, log):
         if not log.handlers:
@@ -467,6 +471,13 @@ class Chalice(object):
                     return True
         return False
 
+    def _configure_log_level(self):
+        if self._debug:
+            level = logging.DEBUG
+        else:
+            level = logging.ERROR
+        self.log.setLevel(level)
+
     def authorizer(self, name=None, **kwargs):
         def _register_authorizer(auth_func):
             auth_name = name
diff --git a/tests/unit/test_app.py b/tests/unit/test_app.py
index 965b670..3c67853 100644
--- a/tests/unit/test_app.py
+++ b/tests/unit/test_app.py
@@ -1185,3 +1185,32 @@ def test_can_use_out_of_order_args():
     response = demo(event, context=None)
     response = json_response_body(response)
     assert response == {'a': 'first', 'b': 'second'}
+
+
+def test_ensure_debug_mode_is_false_by_default():
+    # These logger tests need to each have a unique name because the Chalice
+    # app creates a logger with it's name. If these tests are run in a batch
+    # the logger names will overlap in the logging module and cause test
+    # failures.
+    test_app = app.Chalice('logger-test-1')
+    assert test_app.debug is False
+    assert test_app.log.getEffectiveLevel() == logging.ERROR
+
+
+def test_can_explicitly_set_debug_false_in_initializer():
+    test_app = app.Chalice('logger-test-2', debug=False)
+    assert test_app.debug is False
+    assert test_app.log.getEffectiveLevel() == logging.ERROR
+
+
+def test_can_set_debug_mode_in_initialzier():
+    test_app = app.Chalice('logger-test-3', debug=True)
+    assert test_app.debug is True
+    assert test_app.log.getEffectiveLevel() == logging.DEBUG
+
+
+def test_debug_mode_changes_log_level():
+    test_app = app.Chalice('logger-test-4', debug=False)
+    test_app.debug = True
+    assert test_app.debug is True
+    assert test_app.log.getEffectiveLevel() == logging.DEBUG
['tests/unit/test_app.py', 'chalice/app.py']