Microsoft Azure App Service Extension

Microsoft Azure App Service Extension

Overview

Microsoft Azure App Service is a group of serverless resources that enable you to build and host web apps, mobile back ends, event-driven functions, and RESTful APIs without managing infrastructure. It can host workloads of all sizes and offers auto-scaling and high availability options.

Datadog provides monitoring capabilities for all Azure App Service resource types:

The Datadog extension for Azure App Service provides additional monitoring capabilities for Azure Web Apps. This support includes:

  • Full distributed APM tracing using automatic instrumentation.
  • Support for manual APM instrumentation to customize spans.
  • Trace_ID injection into application logs.
  • Support for submitting custom metrics using DogStatsD.

Setup

Requirements

  1. If you haven’t already, set up the Microsoft Azure integration first.

  2. The extension only supports Azure App Service Web Apps. Function Apps are not supported.

To be notified when a private beta is available for Function Apps or additional runtimes, sign up here.
  1. The Datadog .NET APM extension supports the following .NET runtimes in both x64 and x86 architectures when running on Windows instances (AAS does not yet support extensions on Linux). For more details about automatically instrumented libraries, see the Tracer documentation.

    • .NET Framework 4.5 and later
    • .NET Core 2.1
    • .NET Core 2.2 (Microsoft support ended 2019-12-23)
    • .NET Core 3.0 (Microsoft support ended 2020-03-03)
    • .NET Core 3.1
    • .NET 5
  2. Datadog recommends doing regular updates to the latest version of the extension to ensure optimal performance, stability, and availability of features. Note that both the initial install and subsequent updates require your web app to be fully stopped in order to install/update successfully.

Note: Datadog automatic instrumentation relies on the .NET CLR Profiling API. This API allows only one subscriber (for example, APM). To ensure maximum visibility, run only one APM solution within your application environment.

Installation

  1. Configure the Azure integration to monitor your web app and verify it is configured correctly by ensuring that you see an azure.app_service.count metric tagged with the name of your web application. Note: This step is critical for metric/trace correlation, functional trace panel views in the Datadog portal, and accurate billing.

  2. Open the Azure Portal and navigate to the dashboard for the Azure App Service instance you wish to instrument with Datadog.

  3. Go to the Application settings tab of the Configuration page.

  4. Add your Datadog API key as an application setting called DD_API_KEY and a value of your Datadog API Key.

  5. Configure optional application settings:

    • Set the DD_SITE to (defaults to datadoghq.com).
    • Set DD_ENV to group your traces and custom statistics.
    • Set DD_SERVICE to specify a service name (defaults to your web app name).
    • Set DD_LOGS_INJECTION:true for correlation with application logs from your web app.
    • See a full list of optional configuration variables.
  6. Click Save (this restarts your application).

  7. [REQUIRED] Stop your application by clicking Stop.
  8. Go to the Azure extensions page and select the Datadog APM extension.

  9. Accept the legal terms, click OK, and wait for the installation to complete. Note: the web app must be in a stopped state for this step to complete successfully.

  10. Start the main application, click Start:

Application logging from Azure web apps

Sending logs from your application in Azure App Service to Datadog requires the use of Serilog. Submitting logs with this method allows for trace ID injection, which makes it possible to connect logs and traces in Datadog. To enable trace ID injection with the extension, add the application setting DD_LOGS_INJECTION:true.

Note: Since this occurs inside your application, any Azure Platform logs you submit with diagnostic settings does not include the trace ID.

See documentation on setting up agentless logging with Serilog for detailed instructions.

Custom metrics with DogStatsD

The Azure App Service extension includes an instance of DogStatsD (Datadog’s metrics aggregation service). This enables you to submit custom metrics, service checks, and events directly to Datadog from Azure Web Apps with the extension.

Writing custom metrics and checks in your web app is similar to the process for doing so with an application on a host running the Datadog Agent. To submit custom metrics to Datadog from Azure App Service using the extension:

  1. Add the DogStatsD NuGet package to your Visual Studio project.
  2. Initialize DogStatdD and write custom metrics in your application.
  3. Deploy your code to a supported Azure .NET web app.
  4. Install the Datadog App Service extension.

Note: Unlike the standard DogStatsD config process, there is no need to set ports or a server name when initializing the DogStatsD configuration. There are ambient environment variables in Azure App Service that determine how the metrics are sent (requires v6.0.0+ of the DogStatsD client).

To send metrics use this code:

try
{
// Configure your DogStatsd client and configure any tags
DogStatsd.Configure(new StatsdConfig() { ConstantTags = new[] { "app:sample.mvc.aspnetcore" } });
}
catch (Exception ex)
{
// An exception is thrown by the Configure call if the necessary environment variables are not present.
// These environment variables are present in Azure App Service, but
// need to be set in order to test your custom metrics: DD_API_KEY:{api_key}, DD_AGENT_HOST:localhost
// Ignore or log the exception as it suits you
Console.WriteLine(ex);
}
// Send a metric
DogStatsd.Increment("sample.startup");

Learn more about custom metrics.

Extension management with Powershell

Datadog provides scripts to update or install the Azure App Service Extension using Powershell. Scripted extension management enables you to update extensions in bulk by resource group and designate the installation of specific versions of the site extension. You can also use scripts to programmatically add the extension in CI/CD pipelines, as well as discover and update extensions that are already installed.

Prerequisites

  • The Azure CLI or Azure Cloud Shell.
  • Azure App Service user-scope credentials. If you do not already have credentials, go to your Azure portal and access the App Service instance (Web App or Function App). Navigate to Deployment > Deployment Center to create or retrieve your user-scope credentials.

Installing the extension for the first time

The install script adds the latest version of the extension to an Azure Web App or Azure Function App. This occurs on a per-instance basis, rather than at a resource group level.

  1. Open the Azure CLI or Azure Cloud Shell.

  2. Download the installation script using the following command:

    Invoke-WebRequest -Uri "https://raw.githubusercontent.com/DataDog/datadog-aas-extension/master/management-scripts/extension/install-latest-extension.ps1" -OutFile "install-latest-extension.ps1"
    
  3. Run the following command, passing in required and optional arguments as needed.

    .\install-latest-extension.ps1 -Username <USERNAME> -Password <PASSWORD> -SubscriptionId <SUBSCRIPTION_ID> -ResourceGroup <RESOURCE_GROUP_NAME> -SiteName <SITE_NAME> -DDApiKey <DATADOG_API_KEY> -DDSite <DATADOG_SITE> -DDEnv <DATADOG_ENV> -DDService <DATADOG_SERVICE> -DDVersion <DATADOG_VERSION>
    

Note: The following arguments are required for the above command:

  • <USERNAME>: Your Azure user scope username.
  • <PASSWORD>: Your Azure user scope password.
  • <SUBSCRIPTION_ID>: Your Azure subscription ID.
  • <RESOURCE_GROUP_NAME>: Your Azure resource group name.
  • <SITE_NAME>: The name of your app.
  • <DATADOG_API_KEY>: Your Datadog API key.

Also, set DATADOG_SITE to your Datadog site. DATADOG_SITE defaults to datadoghq.com. Your site is: .

Updating the extension for a resource group

The update script applies to an entire resource group. This script updates every instance (Web App or Function App) that has the extension installed. App Service instances that do not have the Datadog extension installed are not affected.

  1. Open the Azure CLI or Azure Cloud Shell.

  2. Download the installation script using the following command:

    $baseUri="https://raw.githubusercontent.com/DataDog/datadog-aas-extension/master/management-scripts/extension"; Invoke-WebRequest -Uri "$baseUri/update-all-site-extensions.ps1" -OutFile "update-all-site-extensions.ps1"; Invoke-WebRequest -Uri "$baseUri/install-latest-extension.ps1" -OutFile "install-latest-extension.ps1"
    
  3. Run the following command. All arguments are required.

    .\update-all-site-extensions.ps1 -SubscriptionId <SUBSCRIPTION_ID> -ResourceGroup <RESOURCE_GROUP_NAME> -Username <USERNAME> -Password <PASSWORD>
    

Install a specific version of the extension

The Azure App Service UI does not support the ability to install a specific version of an extension. You may do this with the install or update script.

Install specific version on a single resource

To install a specific version on a single instance, follow the instructions for installing the extension for the first time and add the -ExtensionVersion parameter to the installation command.

.\install-latest-extension.ps1 -Username <USERNAME> -Password <PASSWORD> -SubscriptionId <SUBSCRIPTION_ID> -ResourceGroup <RESOURCE_GROUP_NAME> -SiteName <SITE_NAME> -DDApiKey <DATADOG_API_KEY> -ExtensionVersion <EXTENSION_VERSION>

Replace <EXTENSION_VERSION> with the version of the extension you wish to install. For instance, 1.4.0.

Install specific version on an entire resource group

To install a specific version for a resource group, follow the instructions for updating the extension for a resource group and add the -ExtensionVersion parameter to the installation command.

.\update-all-site-extensions.ps1 -SubscriptionId <SUBSCRIPTION_ID> -ResourceGroup <RESOURCE_GROUP_NAME> -Username <USERNAME> -Password <PASSWORD> -ExtensionVersion <EXTENSION_VERSION>

Replace <EXTENSION_VERSION> with the version of the extension you wish to install. For instance, 1.4.0.

ARM template

Many organizations use Azure Resource Management (ARM) templates to implement the practice of infrastructure-as-code. To build the App Service Extension into these templates, incorporate Datadog’s App Service Extension ARM template into your deployments to add the extension and configure it alongside your App Service resources.

Troubleshooting

If your apps are identified as being misconfigured in the Serverless View and/or you are missing corresponding metrics for your traces

It is likely that you do not have the Azure integration configured to monitor your application. Proper configuration improves your ability to correlate metrics, traces, and logs in the Datadog platform. Without the Azure integration configured, you are missing critical context for your traces. To fix this:

  1. Go to the Azure integration tile.

  2. Ensure you have installed the Azure integration for the Azure subscription where your application is running.

  3. Ensure that any App Service plan filtering rules you have applied include the App Service plan where the app is running. If an App Service plan is not included, all apps and functions hosted on it are also not included. Tags on the app itself are not used for filtering by Datadog.

If APM traces are not appearing in Datadog

  1. Verify you’ve set DD_SITE and DD_API_KEY correctly.

  2. Do a full stop and start of your application.

  3. If not resolved, try uninstalling the extension and re-installing (this also ensures you are running the latest version).

Note: To expedite the process of investigating application errors with the support team, set DD_TRACE_DEBUG:true and add the content of the Datadog logs directory (%AzureAppServiceHomeDirectory%\LogFiles\datadog) to your email.

Still need help? Contact Datadog support.

Further Reading