Quickstart: Configure a Durable Functions app to use the Netherite storage provider

Durable Functions offers several storage providers, also called back ends, for storing orchestration and entity runtime state. In this quickstart, you configure an existing Durable Functions app to use the Netherite storage provider. Netherite was designed by Microsoft Research for high-throughput scenarios and can increase throughput by more than an order of magnitude compared to the default Azure Storage provider.

Prerequisites

This quickstart assumes you have an existing Durable Functions app with an orchestrator function and a client function configured for local debugging. If you need to create one first, see the Durable Functions quickstart for your language: C# | JavaScript | Python | PowerShell | Java.

Install the Netherite extension

If your app uses Extension Bundles (the default for non-.NET languages), skip this section. Extension Bundles handles extension management automatically.

For .NET apps, install the latest version of the Microsoft.Azure.Functions.Worker.Extensions.DurableTask.Netherite NuGet package. You can add a reference in your .csproj file, or install it via the CLI.

You can install the extension by using the following Azure Functions Core Tools CLI command:

func extensions install --package <package name depending on your worker model> --version <latest version>

For more information about installing Azure Functions extensions via the Core Tools CLI, see func extensions install.

Configure local.settings.json for local development

The Netherite back end requires Azure Event Hubs when running on Azure, but for local development you can bypass Event Hubs entirely. Setting EventHubsConnection to "SingleHost" runs the Netherite engine in-process without Event Hubs.

In local.settings.json, set the value of EventHubsConnection to SingleHost:

{
  "IsEncrypted": false,
  "Values": {
    "AzureWebJobsStorage": "UseDevelopmentStorage=true",
    "EventHubsConnection": "SingleHost",
    "FUNCTIONS_WORKER_RUNTIME": "<dependent on your programming language>"
  }
}

Update host.json

Edit the storage provider section of the host.json file to set type to Netherite:

{
  "version": "2.0",
  "extensions": {
    "durableTask": {
      "storageProvider": {
        "type": "Netherite"
        }
    }
  }
}

This code snippet is a basic configuration. Common parameters you might add later include PartitionCount (controls parallelism; default is 12) and EventHubsConnection (if you use a non-default app setting name). For the full list, see Netherite configuration settings.

Test locally

Your app is now ready for local development. You can start the function app to test it. One way to start the app is to run func host start on your application's root, and then execute a basic orchestrator function.

While the function app is running, Netherite publishes load information about its active partitions to an Azure Storage table named DurableTaskPartitions. You can use Azure Storage Explorer to verify that it's working as expected. If Netherite is running correctly, the table isn't empty. For an example, see the following screenshot.

For more information about the contents of the DurableTaskPartitions table, see Partition Table.

Configure and deploy to Azure

To run Netherite in Azure, you need an Azure Functions app and an Event Hubs namespace. If you don't have a function app yet, create one in the Azure portal.

Step 1: Create an Event Hubs namespace

Netherite uses Event Hubs for partition management and communication between worker instances.

Complete the steps to create an Event Hubs namespace in the Azure portal. When prompted:

• Resource group: Use the same resource group as your function app.
• Plan and throughput units: Select the defaults. You can change this setting later.
• Retention time: Select the default. This setting has no effect on Netherite.

Step 2: Add the Event Hubs connection string to your app

1. In your Event Hubs namespace, select Shared access policies > RootManagedSharedAccessKey. Copy the value from Connection string-primary key.

   

2. In your function app, select Configuration > New application setting. Set the name to EventHubsConnection and paste the connection string as the value.

   

   

Step 3: Verify platform settings

Check the following settings under Configuration in the Azure portal. Not all settings apply to every app.

• 64-bit architecture (Windows only): Netherite requires 64-bit. Under General Settings, verify that Platform is set to 64 Bit. This setting is the default starting with Azure Functions V4. Linux apps are always 64-bit and don't show this option.

  

• Runtime scale monitoring (Elastic Premium only): If your app is on the Elastic Premium plan, enable runtime scale monitoring for better scaling. Under Function runtime settings, set Runtime Scale Monitoring to On.

  

Step 4: Deploy your app

Deploy your project to the function app. You can use the Azure Functions Core Tools CLI:

func azure functionapp publish <your-function-app-name>

To validate that Netherite is correctly configured after deployment, review the Event Hubs metrics in the Azure portal to ensure there's activity.

For other deployment methods, see the deployment instructions for your language in Prerequisites.

Related content

• Netherite documentation — architecture, configuration, and performance benchmarks
• Storage providers overview — compare Netherite, Azure Storage, MSSQL, and Durable Task Scheduler
• Performance and scale in Durable Functions
• Configure Durable Functions with Durable Task Scheduler — the recommended replacement for Netherite