Update README.md with instructions to run the builder server with sup…

…… (#11678)

Co-authored-by: Lake Mossman <[email protected]>

airbyte-connector-builder-server/README.md

@@ -22,6 +22,12 @@ export CDK_PYTHON=<path_to_CDK_virtual_environment>
 export CDK_ENTRYPOINT=<path_to_CDK_connector_builder_main.py>
 ```
 
+Example commands:
+```
+export CDK_PYTHON=~/code/airbyte/airbyte-cdk/python/.venv/bin/python
+export CDK_ENTRYPOINT=~/code/airbyte/airbyte-cdk/python/airbyte_cdk/connector_builder/main.py
+```
+
 Then run the server (You can also do this w/o build)
 ```bash
 ./gradlew -p oss airbyte-connector-builder-server:run
@@ -41,6 +47,42 @@ CONNECTOR_BUILDER_SERVER_API_HOST=http://host.docker.internal:80
 
 Note: there are two different, but very similarly-named, environment variables; you must edit `CONNECTOR_BUILDER_SERVER_API_HOST`, not `CONNECTOR_BUILDER_API_HOST`.
 
+### Running the platform with support for custom components (docker-compose only)
+
+1. Run the OSS platform locally with builder docker-compose extension
+    1. Example command: PATH_TO_CONNECTORS=/Users/alex/code/airbyte/airbyte-integrations/connectors docker compose -f docker-compose.yaml -f docker-compose.builder.yaml up
+    2. Where PATH_TO_CONNECTORS points to the airbyte-integrations/connectors subdirectory in the opensource airbyte repository
+2. Open the connector builder and develop your connector
+3. When needing a custom componentt:
+    1. Switch to the YAML view
+    2. Define the custom component
+4. Write the custom components and its unit tests
+5. Run test read
+
+Note that connector modules are added to the path at startup time. The platform instance must be restarted if you add a new connector module.
+
+Follow these additional instructions if the connector requires 3rd party libraries that are not available in the CDK:
+
+Developing connectors that require 3rd party libraries can be done by running the connector-builder-server locally and pointing to a custom virtual environment.
+
+1. Create a virtual environment and install the CDK + any 3rd party library required
+2. export CDK_PYTHON=<path_to_virtual_environment>
+ - `CDK_PYTHON` should point to the virtual environment's python executable (example: `export CDK_PYTHON=~/code/airbyte/airbyte-cdk/python/.venv/bin/python`)
+3. export CDK_ENTRYPOINT=<path_to_CDK_connector_builder_main.py>
+4. ./gradlew -p oss airbyte-connector-builder-server:run
+    1. The server is now reachable on localhost:80
+5. Update the server to point to port 80 by editing .env and replacing
+
+    ```
+    CONNECTOR_BUILDER_SERVER_API_HOST=http://airbyte-connector-builder-server:80
+    ```
+    with
+    ```
+    CONNECTOR_BUILDER_SERVER_API_HOST=http://host.docker.internal:80
+    ```
+    
+6. Follow the standard instructions
+
 ## OpenAPI generation
 
 Run it via Gradle by running this from the Airbyte project root: