Application monitoring for Azure App Service and ASP.NET Core

Enabling monitoring on your ASP.NET Core-based web applications running on Azure App Service is now easier than ever. Previously, you needed to manually instrument your app. Now, the latest extension/agent is built into the App Service image by default. This article walks you through enabling Azure Monitor Application Insights monitoring. It also provides preliminary guidance for automating the process for large-scale deployments.

Enable autoinstrumentation monitoring

For a complete list of supported autoinstrumentation scenarios, see Supported environments, languages, and resource providers.

Enable monitoring

1. Select Application Insights in the left pane for your app service. Then select Enable.

   

2. Create a new resource or select an existing Application Insights resource for this application.

   Note

   When you select OK to create a new resource, you're prompted to Apply monitoring settings. Selecting Continue links your new Application Insights resource to your app service. Your app service then restarts.

   

3. After you specify which resource to use, you can choose how you want Application Insights to collect data per platform for your application. ASP.NET Core collection options are Recommended or Disabled.

   

Enable client-side monitoring

Client-side monitoring is enabled by default for ASP.NET Core apps with Recommended collection, regardless of whether the app setting APPINSIGHTS_JAVASCRIPT_ENABLED is present.

If you want to disable client-side monitoring:

1. Select Settings > Configuration.

2. Under Application settings, create a New application setting with the following information:

   • Name: APPINSIGHTS_JAVASCRIPT_ENABLED
   • Value: false

3. Save the settings. Restart your app.

Automate monitoring

To enable telemetry collection with Application Insights, only the application settings must be set.

Application settings definitions

App setting name	Definition	Value
ApplicationInsightsAgent_EXTENSION_VERSION	Main extension, which controls runtime monitoring.	~2 for Windows or ~3 for Linux
XDT_MicrosoftApplicationInsights_Mode	In default mode, only essential features are enabled to ensure optimal performance.	disabled or recommended.
XDT_MicrosoftApplicationInsights_PreemptSdk	For ASP.NET Core apps only. Enables Interop (interoperation) with the Application Insights SDK. Loads the extension side by side with the SDK and uses it to send telemetry. (Disables the Application Insights SDK.)	1

App Service application settings with Azure Resource Manager

Application settings for Azure App Service can be managed and configured with Azure Resource Manager templates. You can use this method when you deploy new App Service resources with Resource Manager automation or modify the settings of existing resources.

The basic structure of the application settings JSON for an App Service resource:

      "resources": [
        {
          "name": "appsettings",
          "type": "config",
          "apiVersion": "2015-08-01",
          "dependsOn": [
            "[resourceId('Microsoft.Web/sites', variables('webSiteName'))]"
          ],
          "tags": {
            "displayName": "Application Insights Settings"
          },
          "properties": {
            "key1": "value1",
            "key2": "value2"
          }
        }
      ]

For an example of a Resource Manager template with application settings configured for Application Insights, this template can be helpful. Specifically, see the section that starts on line 238.

Automate the creation of an Application Insights resource and link to your newly created App Service resource

To create a Resource Manager template with the default Application Insights settings, begin the process as if you were going to create a new web app with Application Insights enabled.

1. Create a new App Service resource with your desired web app information. Enable Application Insights on the Monitoring tab.

2. Select Review + create. Then select Download a template for automation.

   

   This option generates the latest Resource Manager template with all required settings configured.

   

In the following sample, replace all instances of AppMonitoredSite with your site name:

{
    "resources": [
        {
            "name": "[parameters('name')]",
            "type": "Microsoft.Web/sites",
            "properties": {
                "siteConfig": {
                    "appSettings": [
                        {
                            "name": "APPINSIGHTS_INSTRUMENTATIONKEY",
                            "value": "[reference('microsoft.insights/components/AppMonitoredSite', '2015-05-01').InstrumentationKey]"
                        },
                        {
                            "name": "APPLICATIONINSIGHTS_CONNECTION_STRING",
                            "value": "[reference('microsoft.insights/components/AppMonitoredSite', '2015-05-01').ConnectionString]"
                        },
                        {
                            "name": "ApplicationInsightsAgent_EXTENSION_VERSION",
                            "value": "~2"
                        }
                    ]
                },
                "name": "[parameters('name')]",
                "serverFarmId": "[concat('/subscriptions/', parameters('subscriptionId'),'/resourcegroups/', parameters('serverFarmResourceGroup'), '/providers/Microsoft.Web/serverfarms/', parameters('hostingPlanName'))]",
                "hostingEnvironment": "[parameters('hostingEnvironment')]"
            },
            "dependsOn": [
                "[concat('Microsoft.Web/serverfarms/', parameters('hostingPlanName'))]",
                "microsoft.insights/components/AppMonitoredSite"
            ],
            "apiVersion": "2016-03-01",
            "location": "[parameters('location')]"
        },
        {
            "apiVersion": "2016-09-01",
            "name": "[parameters('hostingPlanName')]",
            "type": "Microsoft.Web/serverfarms",
            "location": "[parameters('location')]",
            "properties": {
                "name": "[parameters('hostingPlanName')]",
                "workerSizeId": "[parameters('workerSize')]",
                "numberOfWorkers": "1",
                "hostingEnvironment": "[parameters('hostingEnvironment')]"
            },
            "sku": {
                "Tier": "[parameters('sku')]",
                "Name": "[parameters('skuCode')]"
            }
        },
        {
            "apiVersion": "2015-05-01",
            "name": "AppMonitoredSite",
            "type": "microsoft.insights/components",
            "location": "China North 2",
            "properties": {
                "ApplicationId": "[parameters('name')]",
                "Request_Source": "IbizaWebAppExtensionCreate"
            }
        }
    ],
    "parameters": {
        "name": {
            "type": "string"
        },
        "hostingPlanName": {
            "type": "string"
        },
        "hostingEnvironment": {
            "type": "string"
        },
        "location": {
            "type": "string"
        },
        "sku": {
            "type": "string"
        },
        "skuCode": {
            "type": "string"
        },
        "workerSize": {
            "type": "string"
        },
        "serverFarmResourceGroup": {
            "type": "string"
        },
        "subscriptionId": {
            "type": "string"
        }
    },
    "$schema": "https://schema.management.azure.com/schemas/2014-04-01-preview/deploymentTemplate.json#",
    "contentVersion": "1.0.0.0"
}

Enable through PowerShell

To enable the application monitoring through PowerShell, only the underlying application settings must be changed. The following sample enables application monitoring for a website called AppMonitoredSite in the resource group AppMonitoredRG. It configures data to be sent to the 012345678-abcd-ef01-2345-6789abcd instrumentation key.

$app = Get-AzWebApp -ResourceGroupName "AppMonitoredRG" -Name "AppMonitoredSite" -ErrorAction Stop
$newAppSettings = @{} # case-insensitive hash map
$app.SiteConfig.AppSettings | %{$newAppSettings[$_.Name] = $_.Value} # preserve non Application Insights application settings.
$newAppSettings["APPINSIGHTS_INSTRUMENTATIONKEY"] = "012345678-abcd-ef01-2345-6789abcd"; # set the Application Insights instrumentation key
$newAppSettings["APPLICATIONINSIGHTS_CONNECTION_STRING"] = "InstrumentationKey=012345678-abcd-ef01-2345-6789abcd"; # set the Application Insights connection string
$newAppSettings["ApplicationInsightsAgent_EXTENSION_VERSION"] = "~2"; # enable the ApplicationInsightsAgent
$app = Set-AzWebApp -AppSettings $newAppSettings -ResourceGroupName $app.ResourceGroup -Name $app.Name -ErrorAction Stop

Upgrade monitoring extension/agent - .NET

To upgrade the monitoring extension/agent, follow the steps in the next sections.

Upgrade from versions 2.8.9 and up

Upgrading from version 2.8.9 happens automatically, without any extra actions. The new monitoring bits are delivered in the background to the target app service, and on application restart they'll be picked up.

To check which version of the extension you're running, go to https://yoursitename.scm.chinacloudsites.cn/ApplicationInsights.

Upgrade from versions 1.0.0 - 2.6.5

Starting with version 2.8.9, the preinstalled site extension is used. If you're using an earlier version, you can update via one of two ways:

• Upgrade by enabling via the portal: Even if you have the Application Insights extension for App Service installed, the UI shows only the Enable button. Behind the scenes, the old private site extension will be removed.

• Upgrade through PowerShell:

  1. Set the application settings to enable the preinstalled site extension ApplicationInsightsAgent. For more information, see Enable through PowerShell.
  2. Manually remove the private site extension named Application Insights extension for Azure App Service.

If the upgrade is done from a version prior to 2.5.1, check that the ApplicationInsights DLLs are removed from the application bin folder. For more information, see Troubleshooting steps.

Troubleshooting

What follows is our step-by-step troubleshooting guide for extension/agent-based monitoring for ASP.NET Core-based applications running on App Service.

Default website deployed with web apps doesn't support automatic client-side monitoring

When you create a web app with the ASP.NET Core runtimes in App Service, it deploys a single static HTML page as a starter website. The static webpage also loads an ASP.NET-managed web part in IIS. This behavior allows for testing codeless server-side monitoring but doesn't support automatic client-side monitoring.

If you want to test out codeless server and client-side monitoring for ASP.NET Core in an App Service web app, we recommend that you follow the official guides for creating an ASP.NET Core web app. Then use the instructions in the current article to enable monitoring.

What's the difference between standard metrics from Application Insights vs. Azure App Service metrics?

Application Insights collects telemetry for the requests that made it to the application. If the failure occurs in WebApps/WebServer, and the request didn't reach the user application, Application Insights doesn't have any telemetry about it.

The duration for serverresponsetime calculated by Application Insights doesn't necessarily match the server response time observed by Web Apps. This behavior is because Application Insights only counts the duration when the request actually reaches the user application. If the request is stuck or queued in WebServer, the waiting time is included in the Web Apps metrics but not in Application Insights metrics.

Test connectivity between your application host and the ingestion service

Application Insights SDKs and agents send telemetry to get ingested as REST calls to our ingestion endpoints. You can test connectivity from your web server or application host machine to the ingestion service endpoints by using raw REST clients from PowerShell or curl commands. See Troubleshoot missing application telemetry in Azure Monitor Application Insights.

PHP and WordPress aren't supported

PHP and WordPress sites aren't supported. There's currently no officially supported SDK/agent for server-side monitoring of these workloads. To manually instrument client-side transactions on a PHP or WordPress site by adding the client-side JavaScript to your webpages, use the JavaScript SDK.

The following table provides an explanation of what these values mean, their underlying causes, and recommended fixes.

Problem value	Explanation	Fix
AppAlreadyInstrumented:true	This value indicates that the extension detected that some aspect of the SDK is already present in the application and will back off. It can be because of a reference to Microsoft.ApplicationInsights.AspNetCore or Microsoft.ApplicationInsights.	Remove the references. Some of these references are added by default from certain Visual Studio templates. Older versions of Visual Studio reference Microsoft.ApplicationInsights.
AppAlreadyInstrumented:true	This value can also be caused by the presence of Microsoft.ApplicationsInsights DLL in the app folder from a previous deployment.	Clean the app folder to ensure that these DLLs are removed. Check both your local app's bin directory and the wwwroot directory on the App Service. (To check the wwwroot directory of your App Service web app, select Advanced Tools (Kudu) > Debug console > CMD > home\site\wwwroot).
IKeyExists:false	This value indicates that the instrumentation key isn't present in the app setting APPINSIGHTS_INSTRUMENTATIONKEY. Possible causes include accidentally removing the values or forgetting to set the values in automation script.	Make sure the setting is present in the App Service application settings.

Release notes

For the latest updates and bug fixes, see the Release notes.

Next steps

• Run the Profiler on your live app.
• Monitor Azure Functions with Application Insights.
• Enable Azure diagnostics to be sent to Application Insights.
• Monitor service health metrics to make sure your service is available and responsive.
• Receive alert notifications whenever operational events happen or metrics cross a threshold.
• Use Application Insights for JavaScript apps and webpages to get client telemetry from the browsers that visit a webpage.
• Availability