feat: Propagate all env vars with DATACONTRACT_SNOWFLAKE_ prefix (#339)

According to Soda documentation:
https://docs.soda.io/soda/connect-snowflake.html
All parameters from the official
Snowflake Python Connector library
are supported.
Thus, we only need to propagate them
from environmental variables
to the underlying Soda configuration.

Co-authored-by: Taras Slipets <taras.slipets@flixbus.com>

README.md

@@ -588,14 +588,31 @@ models:
 ```
 
 #### Environment Variables
-
-| Environment Variable               | Example            | Description                                         |
-|------------------------------------|--------------------|-----------------------------------------------------|
-| `DATACONTRACT_SNOWFLAKE_USERNAME`  | `datacontract`     | Username                                            |
-| `DATACONTRACT_SNOWFLAKE_PASSWORD`  | `mysecretpassword` | Password                                            |
-| `DATACONTRACT_SNOWFLAKE_ROLE`      | `DATAVALIDATION`   | The snowflake role to use.                          |
-| `DATACONTRACT_SNOWFLAKE_WAREHOUSE` | `COMPUTE_WH`       | The Snowflake Warehouse to use executing the tests. |
-
+All [parameters supported by Soda](https://docs.soda.io/soda/connect-snowflake.html), uppercased and prepended by `DATACONTRACT_SNOWFLAKE_` prefix.  
+For example:
+
+| Soda parameter       | Environment Variable                        | 
+|----------------------|---------------------------------------------|
+| `username`           | `DATACONTRACT_SNOWFLAKE_USERNAME`           |
+| `password`           | `DATACONTRACT_SNOWFLAKE_PASSWORD`           |
+| `warehouse`          | `DATACONTRACT_SNOWFLAKE_WAREHOUSE`          |
+| `role`               | `DATACONTRACT_SNOWFLAKE_ROLE`               |
+| `connection_timeout` | `DATACONTRACT_SNOWFLAKE_CONNECTION_TIMEOUT` |
+
+Beware, that parameters:
+* `account`
+* `database`
+* `schema`
+
+are obtained from the `servers` section of the YAML-file.  
+E.g. from the example above:
+```yaml
+servers:
+  snowflake:
+    account: abcdefg-xn12345
+    database: ORDER_DB
+    schema: ORDERS_PII_V2
+```
 
 
 ### Kafka

datacontract/engines/soda/connections/snowflake.py

@@ -4,17 +4,20 @@
 
 
 def to_snowflake_soda_configuration(server):
+    prefix = "DATACONTRACT_SNOWFLAKE_"
+    snowflake_soda_params = {k.replace(prefix, "").lower(): v for k, v in os.environ.items() if k.startswith(prefix)}
+
+    # backward compatibility
+    if "connection_timeout" not in snowflake_soda_params:
+        snowflake_soda_params["connection_timeout"] = "5"  # minutes
+
     soda_configuration = {
         f"data_source {server.type}": {
             "type": "snowflake",
-            "username": os.getenv("DATACONTRACT_SNOWFLAKE_USERNAME"),
-            "password": os.getenv("DATACONTRACT_SNOWFLAKE_PASSWORD"),
-            "role": os.getenv("DATACONTRACT_SNOWFLAKE_ROLE"),
             "account": server.account,
             "database": server.database,
             "schema": server.schema_,
-            "warehouse": os.getenv("DATACONTRACT_SNOWFLAKE_WAREHOUSE"),
-            "connection_timeout": 5,  # minutes
+            **snowflake_soda_params,
         }
     }
     soda_configuration_str = yaml.dump(soda_configuration)