this is a basic CRUD for documents in AZURE COSMOS DB, you should be able to define your own app config for establishing a connection with your own DB, there is a method that defines a storage proceedure. the app config (xml) you could define it as:
<?xml version="1.0" encoding = "utf-8"?> <configuration>
<appSettings>
<add key="accountEndPoint" value = "your uri"/>
<add key ="accountKey" value=" key generated by AZURE" />
</appSettings> </configuration>
you could define it as an app setting json... as you want.