Allow endpoints to specify explicit http methods

src/middlewared/middlewared/restful.py

@@ -142,6 +142,10 @@ async def register_resources(self):
                     res_kwargs['post'] = methodname
                 else:
                     res_kwargs['get'] = methodname
+                for rest_method in (method['explicit_methods'] or []):
+                    assert rest_method in ('post', 'get')
+                    res_kwargs[rest_method] = methodname
+
                 Resource(self, self.middleware, short_methodname, service['config'], parent=parent, **res_kwargs)
             await asyncio.sleep(0)  # Force context switch
 

src/middlewared/middlewared/service.py

@@ -181,6 +181,23 @@ def wrapper(fn):
     return wrapper
 
 
+def rest_api_metadata(explicit_methods=None):
+    """
+    Allow having endpoints specify explicit rest methods.
+
+    Explicit methods should be a list which specifies what methods the function should be available
+    at other then the default one it is already going to be. This is useful when we want to maintain
+    backwards compatibility with endpoints which were not expecting payload before but are now and users
+    still would like to consume them with previous method which would be GET whereas it's POST now.
+    """
+    def wrapper(fn):
+        fn._rest_api_metadata = {
+            'explicit_methods': explicit_methods,
+        }
+        return fn
+    return wrapper
+
+
 def periodic(interval, run_on_start=True):
     def wrapper(fn):
         fn._periodic = PeriodicTaskDescriptor(interval, run_on_start)
@@ -1070,6 +1087,8 @@ def get_methods(self, service, cli):
                     'filterable': hasattr(method, '_filterable'),
                     'filterable_schema': None,
                     'pass_application': hasattr(method, '_pass_app'),
+                    'explicit_methods': method._rest_api_metadata['explicit_methods'] if hasattr(
+                        method, '_rest_api_metadata') else None,
                     'require_websocket': hasattr(method, '_pass_app') and not method._pass_app['rest'],
                     'job': hasattr(method, '_job'),
                     'downloadable': hasattr(method, '_job') and 'output' in method._job['pipes'],