---
title: Azure Functions
description: Set up the Elastic APM .NET agent to trace Azure Functions invocations using the isolated worker or in-process execution model.
url: https://www.elastic.co/elastic/docs-builder/docs/3400/reference/apm/agents/dotnet/setup-azure-functions
products:
  - APM .NET Agent
  - APM Agent
applies_to:
  - Serverless Observability projects: Generally available
  - Elastic Stack: Generally available
  - Application Performance Monitoring Agent for .NET: Generally available
---

# Azure Functions
The .NET APM Agent can trace function invocations in an [Azure Functions](https://learn.microsoft.com/en-us/azure/azure-functions) app. Two execution models are supported.
**Don't know which model you're using?** Isolated worker is the recommended and current model. In-process is legacy (reaching end-of-support November 10, 2026). If you're creating a new Azure Function app, use **isolated worker**. If you have an existing in-process app and want to add APM, you'll find instructions in the in-process section below.

## Supported versions


| Hosting model                   | Package                                | Supported versions |
|---------------------------------|----------------------------------------|--------------------|
| Isolated worker                 | `Microsoft.Azure.Functions.Worker`     | ≥2.0.0 <3.0.0      |
| In-process (legacy, deprecated) | `Microsoft.Azure.Functions.Extensions` | ≥1.1.0 <2.0.0      |

Runtime requirements: The isolated worker model requires .NET 8+. The in-process model supports .NET Framework 4.7.2+ and .NET 8+ (with `FUNCTIONS_INPROC_NET8_ENABLED=1`).
For the full compatibility matrix including supported installation methods, refer to [Azure Functions](/elastic/docs-builder/docs/3400/reference/apm/agents/dotnet/supported-technologies#supported-azure-functions).

## Prerequisites

You need an APM Server to send APM data to. Follow the [APM Quick start](https://docs-v3-preview.elastic.dev/elastic/docs-builder/docs/3400/solutions/observability/apm/get-started) if you have not set one up yet. You need your **APM server URL** and an APM server **API key** for configuring the APM agent below. (If your APM Server uses secret tokens instead, both are supported.)
You also need an Azure Function app to monitor running on **.NET 8+** (for isolated worker model) or **.NET Framework 4.7.2+ or .NET 8+** (for in-process model; .NET 8 requires the `FUNCTIONS_INPROC_NET8_ENABLED=1` setting). If you do not have an existing one, you can follow [Create your first C# function in Azure](https://learn.microsoft.com/en-us/azure/azure-functions/create-first-function-cli-csharp) to create one.

## Azure Functions isolated worker model

You can also take a look at and use this [Azure Functions isolated worker example](https://github.com/elastic/apm-agent-dotnet/tree/main/test/azure/applications/Elastic.AzureFunctionApp.Isolated) app with Elastic APM already integrated.

### Step 1: Add the NuGet package

Add the `Elastic.Apm.Azure.Functions` NuGet package to your Azure Functions project:
```bash
dotnet add package Elastic.Apm.Azure.Functions
```


### Step 2: Add the tracing middleware

Register `ApmMiddleware` in your `Program.cs`. The following example uses `ConfigureFunctionsWebApplication`, which is the recommended approach when using the [ASP.NET Core integration](https://learn.microsoft.com/en-us/azure/azure-functions/dotnet-isolated-process-guide#aspnet-core-integration) (requires the `Microsoft.Azure.Functions.Worker.Extensions.Http.AspNetCore` package):
```csharp
using Elastic.Apm.Azure.Functions;
using Microsoft.Extensions.Hosting;

var host = new HostBuilder()
  .ConfigureFunctionsWebApplication(builder =>
  {
    builder.UseMiddleware<ApmMiddleware>();
  })
  .Build();

host.Run();
```

If your app uses `ConfigureFunctionsWorkerDefaults` instead, replace the method name. The middleware registration syntax is the same.

### Step 3: Configure the APM agent

The APM agent can be configured with environment variables.
```yaml
ELASTIC_APM_SERVER_URL: <your APM server URL from the prerequisites step>
ELASTIC_APM_API_KEY: <your APM API key from the prerequisites step>
ELASTIC_APM_ENVIRONMENT: <your environment>
ELASTIC_APM_SERVICE_NAME: <your service name> (optional)
```

If `ELASTIC_APM_SERVICE_NAME` is not configured, the agent will use a fallback value.
- **Local development** - The discovered service name (the entry Assembly name) will be used.
- **Azure** - The Function App name (retrieved from the `WEBSITE_SITE_NAME` environment variable) will be used.

**Configuring in Local development**
While developing your Function locally, you can configure the agent by providing the environment variables via the `local.settings.json` file.
For example:
```json
{
  "IsEncrypted": false,
  "Values": {
    "AzureWebJobsStorage": "UseDevelopmentStorage=true",
    "FUNCTIONS_WORKER_RUNTIME": "dotnet-isolated",
    "ELASTIC_APM_ENVIRONMENT": "Development",
    "ELASTIC_APM_SERVICE_NAME": "MyServiceName",
    "ELASTIC_APM_SERVER_URL": "https://your-apm-server:443",
    "ELASTIC_APM_API_KEY": "MySecureApiKeyFromApmServer=="
  }
}
```

**Configuring in Azure**
Using environment variables allows you to use [application settings in the Azure Portal](https://learn.microsoft.com/en-us/azure/azure-functions/functions-how-to-use-azure-function-app-settings?tabs=portal#settings), enabling you to update settings without needing to re-deploy code.
Open *Settings > Environment variables* for your Function App in the Azure Portal and configure the ELASTIC_APM_* variables as required.
For example:
![Configuring the APM Agent in the Azure Portal](https://www.elastic.co/elastic/docs-builder/docs/3400/reference/apm/agents/dotnet/images/azure-functions-configuration.png)
Once configured, see [Verify and troubleshoot](#_verify_and_troubleshoot) to confirm data is flowing.

## Azure Functions in-process model

<important>
  The Azure Functions in-process model reaches end of support on November 10, 2026. We recommend migrating to the [isolated worker model](https://learn.microsoft.com/en-us/azure/azure-functions/migrate-dotnet-to-isolated-model) and following the [isolated worker model setup instructions](#_azure_functions_isolated_worker_model) on this page instead.
</important>

You can also take a look at and use this [Azure Functions in-process example](https://github.com/elastic/apm-agent-dotnet/tree/main/test/azure/applications/Elastic.AzureFunctionApp.InProcess) app with Elastic APM already integrated.

### Step 1: Add the NuGet package

Add the `Elastic.Apm.Azure.Functions` NuGet package to your Azure Functions project:
```bash
dotnet add package Elastic.Apm.Azure.Functions
```


### Step 2: Register the APM agent

The in-process model does not support middleware. Instead, create a startup class that inherits `FunctionsStartup` and call `AddElasticApm()` on the `IFunctionsHostBuilder`:
```csharp
using Elastic.Apm.Azure.Functions;
using Microsoft.Azure.Functions.Extensions.DependencyInjection;

[assembly: FunctionsStartup(typeof(MyNamespace.Startup))]

namespace MyNamespace;

public class Startup : FunctionsStartup
{
    public override void Configure(IFunctionsHostBuilder builder) =>
        builder.AddElasticApm();
}
```

The `[assembly: FunctionsStartup]` attribute tells the Azure Functions runtime to invoke this class at startup. No changes to individual function classes are needed.

### Step 3: Configure the APM agent

The APM agent is configured with environment variables:
```yaml
ELASTIC_APM_SERVER_URL: <your APM server URL from the prerequisites step>
ELASTIC_APM_API_KEY: <your APM API key from the prerequisites step>
ELASTIC_APM_ENVIRONMENT: <your environment>
ELASTIC_APM_SERVICE_NAME: <your service name> (optional)
```

If `ELASTIC_APM_SERVICE_NAME` is not configured, the agent uses the same fallback values as the isolated worker model:
- **Local development** - The discovered service name (the entry assembly name) will be used.
- **Azure** - The Function App name (retrieved from the `WEBSITE_SITE_NAME` environment variable) will be used.

**Configuring for local development**
Add the `ELASTIC_APM_*` variables to your `local.settings.json` file. Note that `FUNCTIONS_WORKER_RUNTIME` must be set to `dotnet` (not `dotnet-isolated`). When targeting .NET 8, the `FUNCTIONS_INPROC_NET8_ENABLED` setting is also required to opt in to in-process support on that runtime:
```json
{
  "IsEncrypted": false,
  "Values": {
    "AzureWebJobsStorage": "UseDevelopmentStorage=true",
    "FUNCTIONS_WORKER_RUNTIME": "dotnet",
    "FUNCTIONS_INPROC_NET8_ENABLED": "1",
    "ELASTIC_APM_ENVIRONMENT": "Development",
    "ELASTIC_APM_SERVICE_NAME": "MyServiceName",
    "ELASTIC_APM_SERVER_URL": "https://your-apm-server:443",
    "ELASTIC_APM_API_KEY": "MySecureApiKeyFromApmServer=="
  }
}
```

**Configuring in Azure**
Open *Settings → Environment variables* for your Function App in the Azure Portal and configure the `ELASTIC_APM_*` variables as required. If targeting .NET 8, also add `FUNCTIONS_INPROC_NET8_ENABLED` with a value of `1`.
Using environment variables allows you to use [application settings in the Azure Portal](https://learn.microsoft.com/en-us/azure/azure-functions/functions-how-to-use-azure-function-app-settings?tabs=portal#settings), enabling you to update settings without needing to re-deploy code.
Once configured, see [Verify and troubleshoot](#_verify_and_troubleshoot) to confirm data is flowing.

## Verify and troubleshoot

**Verify in Kibana**
After deploying your function or running it locally:
1. Open Kibana and navigate to **Observability** → **Applications** → **Service inventory**
2. Look for your service name (configured via `ELASTIC_APM_SERVICE_NAME` or the function app name)
3. Click on the service to see captured transactions and spans

On Consumption plans, allow 30-60 seconds for the first transaction to appear after invoking your function.
**Service doesn't appear in Kibana**
- Verify `ELASTIC_APM_SERVER_URL` is reachable and correct
- Confirm `ELASTIC_APM_API_KEY` has the required privileges on your APM Server
- Check your function's application logs in the Azure Portal for APM-related errors
- Invoke the function at least once to generate a transaction

**No transactions appear locally**
- Ensure the APM Server URL in `local.settings.json` is accessible (not `localhost` if running in Docker)
- Verify your function was actually invoked (check the HTTP response)
- Confirm middleware is registered correctly in `Program.cs` (isolated model) or `Startup.cs` (in-process model)


## Limitations

Azure Functions instrumentation currently does *not* collect system metrics (CPU, memory, garbage collection) in the background because of a concern with unintentionally increasing Azure Functions costs (for Consumption plans). However, **all transactions, spans, and application-level data are still collected**.
The **in-process model** only traces HTTP-triggered function invocations. Non-HTTP triggers (such as Timer, Queue, and Service Bus triggers) are not captured. If you need tracing for non-HTTP triggers, migrate to the [isolated worker model](https://learn.microsoft.com/en-us/azure/azure-functions/migrate-dotnet-to-isolated-model) and follow the [isolated worker setup instructions](#_azure_functions_isolated_worker_model) on this page. The **isolated worker model** traces all trigger types.