Refactor call pattern for switching between clients (#81)

* Added a 'request_wrapper' that abstracts away the logic to switch between Envoy clients and basic HTTP requests.

amundsen_application/api/metadata/v0.py

 import logging
-import requests
 
 from http import HTTPStatus
 from typing import Any, Dict
@@ -12,7 +11,7 @@ from amundsen_application.log.action_log import action_logging
 
 from amundsen_application.models.user import load_user, dump_user
 
-from amundsen_application.api.utils.request_utils import get_query_param
+from amundsen_application.api.utils.request_utils import get_query_param, request_wrapper
 
 LOGGER = logging.getLogger(__name__)
 
@@ -69,14 +68,11 @@ def popular_tables() -> Response:
     try:
         url = app.config['METADATASERVICE_BASE'] + POPULAR_TABLES_ENDPOINT
 
-        # TODO: Create an abstraction for this logic that is reused many times
-        if app.config['METADATASERVICE_REQUEST_CLIENT'] is not None:
-            envoy_client = app.config['METADATASERVICE_REQUEST_CLIENT']
-            envoy_headers = app.config['METADATASERVICE_REQUEST_HEADERS']
-            response = envoy_client.get(url, headers=envoy_headers, raw_response=True)
-        else:
-            with requests.Session() as s:
-                response = s.get(url, timeout=REQUEST_SESSION_TIMEOUT)
+        response = request_wrapper(method='GET',
+                                   url=url,
+                                   client=app.config['METADATASERVICE_REQUEST_CLIENT'],
+                                   headers=app.config['METADATASERVICE_REQUEST_HEADERS'],
+                                   timeout_sec=REQUEST_SESSION_TIMEOUT)
 
         status_code = response.status_code
 
@@ -124,14 +120,11 @@ def get_table_metadata() -> Response:
 
 
 def _send_metadata_get_request(url: str) -> Response:
-    # TODO: Create an abstraction for this logic that is reused many times
-    if app.config['METADATASERVICE_REQUEST_CLIENT'] is not None:
-        envoy_client = app.config['METADATASERVICE_REQUEST_CLIENT']
-        envoy_headers = app.config['METADATASERVICE_REQUEST_HEADERS']
-        return envoy_client.get(url, headers=envoy_headers, raw_response=True)
-    else:
-        with requests.Session() as s:
-            return s.get(url, timeout=REQUEST_SESSION_TIMEOUT)
+    return request_wrapper(method='GET',
+                           url=url,
+                           client=app.config['METADATASERVICE_REQUEST_CLIENT'],
+                           headers=app.config['METADATASERVICE_REQUEST_HEADERS'],
+                           timeout_sec=REQUEST_SESSION_TIMEOUT)
 
 
 def _get_partition_data(watermarks: Dict) -> Dict:
@@ -240,20 +233,11 @@ def _update_table_owner(*, table_key: str, method: str, owner: str) -> Dict[str,
         table_endpoint = _get_table_endpoint()
         url = '{0}/{1}/owner/{2}'.format(table_endpoint, table_key, owner)
 
-        # TODO: Create an abstraction for this logic that is reused many times
-        if app.config['METADATASERVICE_REQUEST_CLIENT'] is not None:
-            envoy_client = app.config['METADATASERVICE_REQUEST_CLIENT']
-            envoy_headers = app.config['METADATASERVICE_REQUEST_HEADERS']
-            if method == 'PUT':
-                envoy_client.put(url, headers=envoy_headers)
-            else:
-                envoy_client.delete(url, headers=envoy_headers)
-        else:
-            with requests.Session() as s:
-                if method == 'PUT':
-                    s.put(url, timeout=REQUEST_SESSION_TIMEOUT)
-                else:
-                    s.delete(url, timeout=REQUEST_SESSION_TIMEOUT)
+        request_wrapper(method=method,
+                        url=url,
+                        client=app.config['METADATASERVICE_REQUEST_CLIENT'],
+                        headers=app.config['METADATASERVICE_REQUEST_HEADERS'],
+                        timeout_sec=REQUEST_SESSION_TIMEOUT)
 
         # TODO: Figure out a way to get this payload from flask.jsonify which wraps with app's response_class
         return {'msg': 'Updated owner'}
@@ -286,14 +270,11 @@ def get_last_indexed() -> Response:
     try:
         url = app.config['METADATASERVICE_BASE'] + LAST_INDEXED_ENDPOINT
 
-        # TODO: Create an abstraction for this logic that is reused many times
-        if app.config['METADATASERVICE_REQUEST_CLIENT'] is not None:
-            envoy_client = app.config['METADATASERVICE_REQUEST_CLIENT']
-            envoy_headers = app.config['METADATASERVICE_REQUEST_HEADERS']
-            response = envoy_client.get(url, headers=envoy_headers, raw_response=True)
-        else:
-            with requests.Session() as s:
-                response = s.get(url, timeout=REQUEST_SESSION_TIMEOUT)
+        response = request_wrapper(method='GET',
+                                   url=url,
+                                   client=app.config['METADATASERVICE_REQUEST_CLIENT'],
+                                   headers=app.config['METADATASERVICE_REQUEST_HEADERS'],
+                                   timeout_sec=REQUEST_SESSION_TIMEOUT)
 
         status_code = response.status_code
 
@@ -319,14 +300,11 @@ def get_table_description() -> Response:
 
         url = '{0}/{1}/description'.format(table_endpoint, table_key)
 
-        # TODO: Create an abstraction for this logic that is reused many times
-        envoy_client = app.config['METADATASERVICE_REQUEST_CLIENT']
-        if envoy_client is not None:
-            envoy_headers = app.config['METADATASERVICE_REQUEST_HEADERS']
-            response = envoy_client.get(url, headers=envoy_headers, raw_response=True)
-        else:
-            with requests.Session() as s:
-                response = s.get(url, timeout=REQUEST_SESSION_TIMEOUT)
+        response = request_wrapper(method='GET',
+                                   url=url,
+                                   client=app.config['METADATASERVICE_REQUEST_CLIENT'],
+                                   headers=app.config['METADATASERVICE_REQUEST_HEADERS'],
+                                   timeout_sec=REQUEST_SESSION_TIMEOUT)
 
         status_code = response.status_code
 
@@ -354,14 +332,11 @@ def get_column_description() -> Response:
 
         url = '{0}/{1}/column/{2}/description'.format(table_endpoint, table_key, column_name)
 
-        # TODO: Create an abstraction for this logic that is reused many times
-        envoy_client = app.config['METADATASERVICE_REQUEST_CLIENT']
-        if envoy_client is not None:
-            envoy_headers = app.config['METADATASERVICE_REQUEST_HEADERS']
-            response = envoy_client.get(url, headers=envoy_headers, raw_response=True)
-        else:
-            with requests.Session() as s:
-                response = s.get(url, timeout=REQUEST_SESSION_TIMEOUT)
+        response = request_wrapper(method='GET',
+                                   url=url,
+                                   client=app.config['METADATASERVICE_REQUEST_CLIENT'],
+                                   headers=app.config['METADATASERVICE_REQUEST_HEADERS'],
+                                   timeout_sec=REQUEST_SESSION_TIMEOUT)
 
         status_code = response.status_code
 
@@ -399,14 +374,11 @@ def put_table_description() -> Response:
         url = '{0}/{1}/description/{2}'.format(table_endpoint, table_key, description)
         _log_put_table_description(table_key=table_key, description=description, source=src)
 
-        # TODO: Create an abstraction for this logic that is reused many times
-        envoy_client = app.config['METADATASERVICE_REQUEST_CLIENT']
-        if envoy_client is not None:
-            envoy_headers = app.config['METADATASERVICE_REQUEST_HEADERS']
-            response = envoy_client.put(url, headers=envoy_headers, raw_response=True)
-        else:
-            with requests.Session() as s:
-                response = s.put(url, timeout=REQUEST_SESSION_TIMEOUT)
+        response = request_wrapper(method='PUT',
+                                   url=url,
+                                   client=app.config['METADATASERVICE_REQUEST_CLIENT'],
+                                   headers=app.config['METADATASERVICE_REQUEST_HEADERS'],
+                                   timeout_sec=REQUEST_SESSION_TIMEOUT)
 
         status_code = response.status_code
 
@@ -444,14 +416,11 @@ def put_column_description() -> Response:
         url = '{0}/{1}/column/{2}/description/{3}'.format(table_endpoint, table_key, column_name, description)
         _log_put_column_description(table_key=table_key, column_name=column_name, description=description, source=src)
 
-        # TODO: Create an abstraction for this logic that is reused many times
-        envoy_client = app.config['METADATASERVICE_REQUEST_CLIENT']
-        if envoy_client is not None:
-            envoy_headers = app.config['METADATASERVICE_REQUEST_HEADERS']
-            response = envoy_client.put(url, headers=envoy_headers, raw_response=True)
-        else:
-            with requests.Session() as s:
-                response = s.put(url, timeout=REQUEST_SESSION_TIMEOUT)
+        response = request_wrapper(method='PUT',
+                                   url=url,
+                                   client=app.config['METADATASERVICE_REQUEST_CLIENT'],
+                                   headers=app.config['METADATASERVICE_REQUEST_HEADERS'],
+                                   timeout_sec=REQUEST_SESSION_TIMEOUT)
 
         status_code = response.status_code
 
@@ -478,14 +447,11 @@ def get_tags() -> Response:
     try:
         url = app.config['METADATASERVICE_BASE'] + TAGS_ENDPOINT
 
-        # TODO: Create an abstraction for this logic that is reused many times
-        if app.config['METADATASERVICE_REQUEST_CLIENT'] is not None:
-            envoy_client = app.config['METADATASERVICE_REQUEST_CLIENT']
-            envoy_headers = app.config['METADATASERVICE_REQUEST_HEADERS']
-            response = envoy_client.get(url, headers=envoy_headers, raw_response=True)
-        else:
-            with requests.Session() as s:
-                response = s.get(url, timeout=REQUEST_SESSION_TIMEOUT)
+        response = request_wrapper(method='GET',
+                                   url=url,
+                                   client=app.config['METADATASERVICE_REQUEST_CLIENT'],
+                                   headers=app.config['METADATASERVICE_REQUEST_HEADERS'],
+                                   timeout_sec=REQUEST_SESSION_TIMEOUT)
 
         status_code = response.status_code
 
@@ -526,20 +492,11 @@ def update_table_tags() -> Response:
 
         _log_update_table_tags(table_key=table_key, method=method, tag=tag)
 
-        # TODO: Create an abstraction for this logic that is reused many times
-        envoy_client = app.config['METADATASERVICE_REQUEST_CLIENT']
-        if envoy_client is not None:
-            envoy_headers = app.config['METADATASERVICE_REQUEST_HEADERS']
-            if method == 'PUT':
-                response = envoy_client.put(url, headers=envoy_headers, raw_response=True)
-            else:
-                response = envoy_client.delete(url, headers=envoy_headers, raw_response=True)
-        else:
-            with requests.Session() as s:
-                if method == 'PUT':
-                    response = s.put(url, timeout=REQUEST_SESSION_TIMEOUT)
-                else:
-                    response = s.delete(url, timeout=REQUEST_SESSION_TIMEOUT)
+        response = request_wrapper(method=method,
+                                   url=url,
+                                   client=app.config['METADATASERVICE_REQUEST_CLIENT'],
+                                   headers=app.config['METADATASERVICE_REQUEST_HEADERS'],
+                                   timeout_sec=REQUEST_SESSION_TIMEOUT)
 
         status_code = response.status_code
 

amundsen_application/api/search/v0.py

 import logging
-import requests
 
 from http import HTTPStatus
 
@@ -10,7 +9,7 @@ from flask import current_app as app
 from flask.blueprints import Blueprint
 
 from amundsen_application.log.action_log import action_logging
-from amundsen_application.api.utils.request_utils import get_query_param
+from amundsen_application.api.utils.request_utils import get_query_param, request_wrapper
 
 LOGGER = logging.getLogger(__name__)
 
@@ -198,14 +197,11 @@ def _search_table(*, search_term: str, page_index: int) -> Dict[str, Any]:
                                                              search_term,
                                                              page_index)
 
-        # TODO: Create an abstraction for this logic that is reused many times
-        if app.config['SEARCHSERVICE_REQUEST_CLIENT'] is not None:
-            envoy_client = app.config['SEARCHSERVICE_REQUEST_CLIENT']
-            envoy_headers = app.config['SEARCHSERVICE_REQUEST_HEADERS']
-            response = envoy_client.get(url, headers=envoy_headers, raw_response=True)
-        else:
-            with requests.Session() as s:
-                response = s.get(url, timeout=REQUEST_SESSION_TIMEOUT)
+        response = request_wrapper(method='GET',
+                                   url=url,
+                                   client=app.config['SEARCHSERVICE_REQUEST_CLIENT'],
+                                   headers=app.config['SEARCHSERVICE_REQUEST_HEADERS'],
+                                   timeout_sec=REQUEST_SESSION_TIMEOUT)
 
         status_code = response.status_code
 

amundsen_application/api/utils/request_utils.py

 from typing import Dict
+import requests
 
 
 def get_query_param(args: Dict, param: str, error_msg: str = None) -> str:
@@ -7,3 +8,39 @@ def get_query_param(args: Dict, param: str, error_msg: str = None) -> str:
         msg = 'A {0} parameter must be provided'.format(param) if error_msg is not None else error_msg
         raise Exception(msg)
     return value
+
+
+# TODO: Define an interface for envoy_client
+def request_wrapper(method: str, url: str, client, headers, timeout_sec: int):  # type: ignore
+    """
+    Wraps a request to use Envoy client and headers, if available
+    :param method: DELETE | GET | POST | PUT
+    :param url: The request URL
+    :param client: Optional Envoy client
+    :param headers: Optional Envoy request headers
+    :param timeout_sec: Number of seconds before timeout is triggered. Not used with Envoy
+    :return:
+    """
+    if client is not None:
+        if method == 'DELETE':
+            return client.delete(url, headers=headers, raw_response=True)
+        elif method == 'GET':
+            return client.get(url, headers=headers, raw_response=True)
+        elif method == 'POST':
+            return client.post(url, headers=headers, raw_response=True)
+        elif method == 'PUT':
+            return client.put(url, headers=headers, raw_response=True)
+        else:
+            raise Exception('Method not allowed: {}'.format(method))
+    else:
+        with requests.Session() as s:
+            if method == 'DELETE':
+                return s.delete(url, timeout=timeout_sec)
+            elif method == 'GET':
+                return s.get(url, timeout=timeout_sec)
+            elif method == 'POST':
+                return s.post(url, timeout=timeout_sec)
+            elif method == 'PUT':
+                return s.put(url, timeout=timeout_sec)
+            else:
+                raise Exception('Method not allowed: {}'.format(method))