Sanity checking for function imports

test_settings.json

@@ -19,7 +19,7 @@
                "expression": "rate(1 minute)"
            },
            {
-               "function": "test.test_app.method",
+               "function": "tests.test_app.method",
                "event_source": {
                    "arn": "arn:aws:sns:::1",
                    "events": [

tests/test_app.py

@@ -21,3 +21,5 @@ def callback(self):
 def prebuild_me():
     print("this is a prebuild script")
 
+def method():
+    print("this is a method")

tests/test_bad_circular_extends_settings.json

@@ -19,7 +19,7 @@
                "expression": "rate(1 minute)"
            },
            {
-               "function": "test.test_app.method",
+               "function": "tests.test_app.method",
                "event_source": {
                    "arn": "arn:aws:sns:::1",
                    "events": [

tests/test_bad_module_paths.json

@@ -0,0 +1,16 @@
+{
+    "ttt888": {
+        "s3_bucket": "lmbda",
+        "app_function": "tests.test_app.hello_world",
+        "delete_local_zip": true,
+        "debug": true,
+        "parameter_depth": 2,
+        "prebuild_script": "tests.test_app.prebuild_me",
+        "events": [
+            {
+                "function": "tests.test_app.not_a_function",
+                "expression": "rate(1 minute)"
+            }
+        ]
+    }
+}

tests/test_bad_settings.json

@@ -19,7 +19,7 @@
                "expression": "rate(1 minute)"
            },
            {
-               "function": "test.test_app.method",
+               "function": "tests.test_app.method",
                "event_source": {
                    "arn": "arn:aws:sns:::1",
                    "events": [

tests/test_bad_stage_name_settings.json

@@ -18,7 +18,7 @@
                "expression": "rate(1 minute)"
            },
            {
-               "function": "test.test_app.method",
+               "function": "tests.test_app.method",
                "event_source": {
                    "arn": "arn:aws:sns:::1",
                    "events": [

tests/test_settings.yml

@@ -14,7 +14,7 @@ ttt888:
   events:
   - function: tests.test_app.schedule_me
     expression: rate(1 minute)
-  - function: test.test_app.method
+  - function: tests.test_app.method
     event_source:
       arn: arn:aws:sns:::1
       events:

tests/tests.py

@@ -899,6 +899,12 @@ def test_bad_environment_vars_catch(self):
         zappa_cli.api_stage = 'ttt888'
         self.assertRaises(ValueError, zappa_cli.load_settings, 'tests/test_bad_environment_vars.json')
 
+    def test_function_sanity_check(self):
+        zappa_cli = ZappaCLI()
+        self.assertRaises(ClickException, zappa_cli.function_sanity_check, 'not_a_module.foo')
+        self.assertRaises(ClickException, zappa_cli.function_sanity_check, 'tests.test_app.not_a_function')
+        self.assertRaises(ClickException, zappa_cli.load_settings, 'test/test_bad_module_paths.json')
+
     # @mock.patch('botocore.session.Session.full_config', new_callable=mock.PropertyMock)
     # def test_cli_init(self, mock_config):
 

zappa/cli.py

@@ -912,7 +912,9 @@ def schedule(self):
                 return
 
         for event in events:
-            self.collision_warning(event.get('function'))
+            if event.get('name') == 'zappa-keep-warm':
+                continue
+            self.function_sanity_check(event.get('function'))
 
         if self.stage_config.get('keep_warm', True):
             if not events:
@@ -1724,12 +1726,15 @@ def load_settings(self, settings_file=None, session=None):
                 setattr(self.zappa, setting, setting_val)
 
         if self.app_function:
-            self.collision_warning(self.app_function)
+            self.function_sanity_check(self.app_function)
             if self.app_function[-3:] == '.py':
                 click.echo(click.style("Warning!", fg="red", bold=True) +
                            " Your app_function is pointing to a " + click.style("file and not a function", bold=True) +
                            "! It should probably be something like 'my_file.app', not 'my_file.py'!")
 
+        if self.exception_handler:
+            self.function_sanity_check(self.exception_handler)
+
         return self.zappa
 
     def get_json_or_yaml_settings(self, settings_name="zappa_settings"):
@@ -2184,12 +2189,13 @@ def execute_prebuild_script(self):
         prebuild_function = getattr(module_, pb_func)
         prebuild_function()  # Call the function
 
-    def collision_warning(self, item):
+    def function_sanity_check(self, item):
         """
         Given a string, print a warning if this could
-        collide with a Zappa core package module.
+        collide with a Zappa core package module, or if the
+        given function could not be correctly imported.
 
-        Use for app functions and events.
+        Use for app functions, event functions, and exception handlers.
         """
 
         namespace_collisions = [
@@ -2201,6 +2207,23 @@ def collision_warning(self, item):
                            " You may have a namespace collision with " + click.style(item, bold=True) +
                            "! You may want to rename that file.")
 
+        module_path, function_path = item.rsplit('.', 1)
+        try:
+            module = importlib.import_module(module_path)
+        except ImportError: # pragma: no cover
+            raise ClickException(
+                "You have tried to reference the module " + click.style(module_path, bold=True) +
+                " when importing " + click.style(item, bold=True) + ", but this module cannot be " +
+                "imported. Please check for typos and ensure that this module is reachable.")
+
+        try:
+            getattr(module, function_path)
+        except AttributeError: # pragma: no cover
+            raise ClickException(
+                "You have tried to reference the function " + click.style(function_path, bold=True) +
+                " when importing " + click.style(item, bold=True) + ", but this function cannot be " +
+                "imported. Please check for typos and ensure that this function is reachable.")
+
     def deploy_api_gateway(self, api_id):
         cache_cluster_enabled = self.stage_config.get('cache_cluster_enabled', False)
         cache_cluster_size = str(self.stage_config.get('cache_cluster_size', .5))