diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index a596d1c4437..1af34624389 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -79,7 +79,18 @@ To add test cases (optional) covering the change in the code generator, please r
 
 To test the templates, please perform the following:
 - Update the [Petstore](http://petstore.swagger.io/) sample by running the shell script under `bin` folder. For example, run `./bin/ruby-petstore.sh` to update the Ruby PetStore API client under [`samples/client/petstore/ruby`](https://github.com/swagger-api/swagger-codegen/tree/master/samples/client/petstore/ruby) For Windows, the batch files can be found under `bin\windows` folder. (If you find that there are new files generated or unexpected changes as a result of the update, that's not unusual as the test cases are added to the OpenAPI/Swagger spec from time to time. If you've questions or concerns, please open a ticket to start a discussion)
+   - To run one of these shell scripts in docker, you can:
+     ```
+     # From the root of this repo
+     docker build -t swagger-codegen .
+     docker run --rm -v $PWD:/cwd -v $PWD/samples:/opt/swagger-codegen/samples swagger-codegen /cwd/bin/<bin file>
+     ```
+   - You may find it helpful to ignore fileMode changes with git: `git -c core.fileMode=false <git command>`
 - Run the tests in the sample folder, e.g. in `samples/client/petstore/ruby`, run `mvn integration-test -rf :RubyPetstoreClientTests`. (some languages may not contain unit testing for Petstore and we're looking for contribution from the community to implement those tests)
+  - You might need a locally running `petstore` server, which can be started with:
+    ```
+    docker run -d -e SWAGGER_HOST=http://petstore.swagger.io -e SWAGGER_BASE_PATH=/v2 -p 80:8080 swaggerapi/petstore
+    ```
 - Finally, git commit the updated samples files: `git commit -a`
   (`git add -A` if added files with new test cases)
 
diff --git a/modules/swagger-codegen/src/main/resources/python/asyncio/rest.mustache b/modules/swagger-codegen/src/main/resources/python/asyncio/rest.mustache
index 39003abfbfd..92482458f3a 100644
--- a/modules/swagger-codegen/src/main/resources/python/asyncio/rest.mustache
+++ b/modules/swagger-codegen/src/main/resources/python/asyncio/rest.mustache
@@ -60,15 +60,10 @@ class RESTClientObject(object):
         )
 
         # https pool manager
-        if configuration.proxy:
-            self.pool_manager = aiohttp.ClientSession(
-                connector=connector,
-                proxy=configuration.proxy
-            )
-        else:
-            self.pool_manager = aiohttp.ClientSession(
-                connector=connector
-            )
+        self.proxy = configuration.proxy
+        self.pool_manager = aiohttp.ClientSession(
+            connector=connector
+        )
 
     async def request(self, method, url, query_params=None, headers=None,
                       body=None, post_params=None, _preload_content=True,
@@ -110,7 +105,8 @@ class RESTClientObject(object):
             "method": method,
             "url": url,
             "timeout": timeout,
-            "headers": headers
+            "headers": headers,
+            "proxy": self.proxy,
         }
 
         if query_params:
diff --git a/samples/client/petstore/python-asyncio/.swagger-codegen/VERSION b/samples/client/petstore/python-asyncio/.swagger-codegen/VERSION
index e3c58351672..be9d3ebd547 100644
--- a/samples/client/petstore/python-asyncio/.swagger-codegen/VERSION
+++ b/samples/client/petstore/python-asyncio/.swagger-codegen/VERSION
@@ -1 +1 @@
-2.4.9-SNAPSHOT
+2.4.13-SNAPSHOT
\ No newline at end of file
diff --git a/samples/client/petstore/python-asyncio/petstore_api/rest.py b/samples/client/petstore/python-asyncio/petstore_api/rest.py
index 69d87b282c6..4ba9ba7a422 100644
--- a/samples/client/petstore/python-asyncio/petstore_api/rest.py
+++ b/samples/client/petstore/python-asyncio/petstore_api/rest.py
@@ -69,15 +69,10 @@ def __init__(self, configuration, pools_size=4, maxsize=4):
         )
 
         # https pool manager
-        if configuration.proxy:
-            self.pool_manager = aiohttp.ClientSession(
-                connector=connector,
-                proxy=configuration.proxy
-            )
-        else:
-            self.pool_manager = aiohttp.ClientSession(
-                connector=connector
-            )
+        self.proxy = configuration.proxy
+        self.pool_manager = aiohttp.ClientSession(
+            connector=connector
+        )
 
     async def request(self, method, url, query_params=None, headers=None,
                       body=None, post_params=None, _preload_content=True,
@@ -119,7 +114,8 @@ async def request(self, method, url, query_params=None, headers=None,
             "method": method,
             "url": url,
             "timeout": timeout,
-            "headers": headers
+            "headers": headers,
+            "proxy": self.proxy,
         }
 
         if query_params: