Add an option to call Nuclio functions via the dashboard

Currently, this only happens when running in Kubernetes. This option lets
CVAT use Nuclio that's deployed to Kubernetes without being deployed to
Kubernetes itself, or just to use Nuclio that is deployed on another
machine.

CHANGELOG.md

@@ -7,7 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## \[2.5.0] - Unreleased
 ### Added
-- TDB
+- A configuration option to control how Nuclio functions are invoked
+  (<https://github.com/opencv/cvat/pull/6146>)
 
 ### Changed
 - Running SAM masks decoder on frontend (<https://github.com/opencv/cvat/pull/6019>)

cvat/apps/lambda_manager/views.py

@@ -89,14 +89,21 @@ def get(self, func_id):
         return response
 
     def invoke(self, func, payload):
-        if os.getenv('KUBERNETES_SERVICE_HOST'):
-            return self._http(method="post", url='/api/function_invocations',
+        invoke_method = {
+            'dashboard': self._invoke_via_dashboard,
+            'direct': self._invoke_directly,
+        }
+
+        return invoke_method[settings.NUCLIO['INVOKE_METHOD']](func, payload)
+
+    def _invoke_via_dashboard(self, func, payload):
+        return self._http(method="post", url='/api/function_invocations',
             data=payload, headers={
                 'x-nuclio-function-name': func.id,
                 'x-nuclio-path': '/'
             })
 
-        # Note: call the function directly without the nuclio dashboard
+    def _invoke_directly(self, func, payload):
         # host.docker.internal for Linux will work only with Docker 20.10+
         NUCLIO_TIMEOUT = settings.NUCLIO['DEFAULT_TIMEOUT']
         if os.path.exists('/.dockerenv'): # inside a docker container

cvat/settings/base.py

@@ -333,9 +333,13 @@ class CVAT_QUEUES(Enum):
     'HOST': os.getenv('CVAT_NUCLIO_HOST', 'localhost'),
     'PORT': int(os.getenv('CVAT_NUCLIO_PORT', 8070)),
     'DEFAULT_TIMEOUT': int(os.getenv('CVAT_NUCLIO_DEFAULT_TIMEOUT', 120)),
-    'FUNCTION_NAMESPACE': os.getenv('CVAT_NUCLIO_FUNCTION_NAMESPACE', 'nuclio')
+    'FUNCTION_NAMESPACE': os.getenv('CVAT_NUCLIO_FUNCTION_NAMESPACE', 'nuclio'),
+    'INVOKE_METHOD': os.getenv('CVAT_NUCLIO_INVOKE_METHOD',
+        default='dashboard' if 'KUBERNETES_SERVICE_HOST' in os.environ else 'direct'),
 }
 
+assert NUCLIO['INVOKE_METHOD'] in {'dashboard', 'direct'}
+
 RQ_SHOW_ADMIN_LINK = True
 RQ_EXCEPTION_HANDLERS = [
     'cvat.apps.engine.views.rq_exception_handler',