Merge pull request #78646 from ealsur/users/ealsur/connectionmode

Adding Azure Cosmos DB Trigger connection mode article

Author: v-shils

articles/cosmos-db/TOC.yml

@@ -535,6 +535,8 @@
       items:
       - name: Azure Cosmos DB Trigger logs
         href: how-to-configure-cosmos-db-trigger-logs.md
+        name: Azure Cosmos DB Trigger connection policy
+        href: how-to-configure-cosmos-db-trigger-connection-policy.md
       - name: Multiple Azure Cosmos DB Triggers
         href: how-to-create-multiple-cosmos-db-triggers.md
       - name: Troubleshoot Azure Cosmos DB Triggers

articles/cosmos-db/how-to-configure-cosmos-db-trigger-connection-policy.md

@@ -0,0 +1,52 @@
+---
+title: Azure Cosmos DB Trigger connection policy
+description: Learn how to configure the connection policy used by Azure Cosmos DB Trigger
+author: ealsur
+ms.service: cosmos-db
+ms.topic: sample
+ms.date: 06/05/2019
+ms.author: maquaran
+---
+
+# How to configure the connection policy used by Azure Cosmos DB Trigger
+
+This article describes how you can configure the connection policy when using the Azure Cosmos DB Trigger to connect to your Azure Cosmos account.
+
+## Why is the connection policy important?
+
+There are two connection modes - Direct mode and Gateway mode. To learn more about these connection modes, see the [performance tips](./performance-tips.md#networking) article. By default, **Gateway** is used to establish all connections on the Azure Cosmos DB Trigger. However, it might not be the best option for performance-driven scenarios.
+
+## Changing the connection mode and protocol
+
+There are two key configuration settings available to configure the client connection policy – the **connection mode** and the **connection protocol**. You can change the default connection mode and protocol used by the Azure Cosmos DB Trigger and all the [Azure Cosmos DB bindings](../azure-functions/functions-bindings-cosmosdb-v2.md#output)). To change the default settings, you need to locate the `host.json` file in your Azure Functions project or Azure Functions App and add the following [extra setting](../azure-functions/functions-bindings-cosmosdb-v2.md#hostjson-settings):
+
+```js
+{
+  "cosmosDB": {
+    "connectionMode": "Direct",
+    "protocol": "Tcp"
+  }
+}
+```
+
+Where `connectionMode` must have the desired connection mode (Direct or Gateway) and `protocol` the desired connection protocol (Tcp or Https). 
+
+If your Azure Functions project is working with Azure Functions V1 runtime, the configuration has a slight name difference, you should use `documentDB` instead of `cosmosDB`:
+
+```js
+{
+  "documentDB": {
+    "connectionMode": "Direct",
+    "protocol": "Tcp"
+  }
+}
+```
+
+> [!NOTE]
+> When working with Azure Functions Consumption Plan Hosting plan, each instance has a limit in the amount of Socket Connections that it can maintain. When working with Direct / TCP mode, by design more connections are created and can hit the [Consumption Plan limit](../azure-functions/manage-connections.md#connection-limit), in which case you can either use Gateway mode or run your Azure Functions in [App Service Mode](../azure-functions/functions-scale.md#app-service-plan).
+
+## Next steps
+
+* [Connection limits in Azure Functions](../azure-functions/manage-connections.md#connection-limit)
+* [Azure Cosmos DB performance tips](./performance-tips.md)
+* [Code samples](https://github.com/ealsur/serverless-recipes/tree/master/connectionmode)