Allow modification of flask app configs (#1030)

* Allow env vars to change flask app behavior

* Run linter

* Convert from string to boolean

* Update documentation

doc/source/python/python_wrapping_docker.md

@@ -105,6 +105,15 @@ The service type being created. Available options are:
 
 Set either to 0 or 1. Default is 0. If set to 1 then your model will be saved periodically to redis and loaded from redis (if exists) or created fresh if not.
 
+### FLASK_JSONIFY_PRETTYPRINT_REGULAR
+
+Sets the flask application configuration `JSONIFY_PRETTYPRINT_REGULAR` for the REST API. Available options are `True`
+or `False`. If nothing is specified, flask's default value is used.
+
+### FLASK_JSON_SORT_KEYS
+
+Sets the flask application configuration `JSON_SORT_KEYS` for the REST API. Available options are `True` or `False`.
+If nothing is specified, flask's default value is used.
 
 ## Creating different service types
 

python/seldon_core/wrapper.py

@@ -22,6 +22,8 @@ def get_rest_microservice(user_model):
     app = Flask(__name__, static_url_path="")
     CORS(app)
 
+    _set_flask_app_configs(app)
+
     if hasattr(user_model, "model_error_handler"):
         logger.info("Registering the custom error handler...")
         app.register_blueprint(user_model.model_error_handler)
@@ -98,6 +100,24 @@ def Aggregate():
     return app
 
 
+def _set_flask_app_configs(app):
+    """
+    Set the configs for the flask app based on environment variables
+    :param app:
+    :return:
+    """
+    env_to_config_map = {
+        "FLASK_JSONIFY_PRETTYPRINT_REGULAR": "JSONIFY_PRETTYPRINT_REGULAR",
+        "FLASK_JSON_SORT_KEYS": "JSON_SORT_KEYS",
+    }
+
+    for env_var, config_name in env_to_config_map.items():
+        if os.environ.get(env_var):
+            # Environment variables come as strings, convert them to boolean
+            bool_env_value = os.environ.get(env_var).lower() == "true"
+            app.config[config_name] = bool_env_value
+
+
 # ----------------------------
 # GRPC
 # ----------------------------