Application Monitoring for Azure App Service and ASP.NET

Članak
06/07/2022
11 min. za čitanje

Enabling monitoring on your ASP.NET based web applications running on Azure App Services is now easier than ever. Whereas previously you needed to manually instrument your app, the latest extension/agent is now built into the App Service image by default. This article will walk you through enabling Azure Monitor application Insights monitoring as well as provide preliminary guidance for automating the process for large-scale deployments.

Note

Manually adding an Application Insights site extension via Development Tools > Extensions is deprecated. This method of extension installation was dependent on manual updates for each new version. The latest stable release of the extension is now preinstalled as part of the App Service image. The files are located in d:\Program Files (x86)\SiteExtensions\ApplicationInsightsAgent and are automatically updated with each stable release. If you follow the auto-instrumentation instructions to enable monitoring below, it will automatically remove the deprecated extension for you.

Note

If both auto-instrumentation monitoring and manual SDK-based instrumentation are detected, only the manual instrumentation settings will be honored. This is to prevent duplicate data from being sent. To learn more about this, check out the troubleshooting section below.

Note

On March 31, 2025, support for instrumentation key ingestion will end. Instrumentation key ingestion will continue to work, but we'll no longer provide updates or support for the feature. Transition to connection strings to take advantage of new capabilities.

Enable auto-instrumentation monitoring

Note

The combination of APPINSIGHTS_JAVASCRIPT_ENABLED and urlCompression is not supported. For more info see the explanation in the troubleshooting section.

Select Application Insights in the Azure control panel for your app service, then select Enable.
Choose to create a new resource, or select an existing Application Insights resource for this application.

Note

When you click OK to create the new resource you will be prompted to Apply monitoring settings. Selecting Continue will link your new Application Insights resource to your app service, doing so will also trigger a restart of your app service.

After specifying which resource to use, you can choose how you want application insights to collect data per platform for your application. ASP.NET app monitoring is on-by-default with two different levels of collection.

Screenshot shows the Application Insights site extensions page with Create new resource selected.

Below is a summary of data collected for each route:

Data	ASP.NET Basic Collection	ASP.NET Recommended collection
Adds CPU, memory, and I/O usage trends	No	Yes
Collects usage trends, and enables correlation from availability results to transactions	Yes	Yes
Collects exceptions unhandled by the host process	Yes	Yes
Improves APM metrics accuracy under load, when sampling is used	Yes	Yes
Correlates micro-services across request/dependency boundaries	No (single-instance APM capabilities only)	Yes

To configure sampling, which you could previously control via the applicationinsights.config file you can now interact with it via Application settings with the corresponding prefix MicrosoftAppInsights_AdaptiveSamplingTelemetryProcessor.
- For example, to change the initial sampling percentage, you can create an Application setting of: MicrosoftAppInsights_AdaptiveSamplingTelemetryProcessor_InitialSamplingPercentage and a value of 100.
- To disable sampling, set MicrosoftAppInsights_AdaptiveSamplingTelemetryProcessor_MinSamplingPercentage to a value of 100.
- Supported settings include:
  - MicrosoftAppInsights_AdaptiveSamplingTelemetryProcessor_InitialSamplingPercentage
  - MicrosoftAppInsights_AdaptiveSamplingTelemetryProcessor_MinSamplingPercentage
  - MicrosoftAppInsights_AdaptiveSamplingTelemetryProcessor_EvaluationInterval
  - MicrosoftAppInsights_AdaptiveSamplingTelemetryProcessor_MaxTelemetryItemsPerSecond
- For the list of supported adaptive sampling telemetry processor settings and definitions, you can consult the code and sampling documentation.

Enable client-side monitoring

Client-side monitoring is opt-in for ASP.NET. To enable client-side monitoring:

Settings > Configuration
- Under Application settings, create a new application setting:
  
  Name: APPINSIGHTS_JAVASCRIPT_ENABLED
  
  Value: true
- Save the settings and Restart your app.

To disable client-side monitoring either remove the associated key value pair from the Application settings, or set the value to false.

Automate monitoring

In order to enable telemetry collection with Application Insights, only the Application settings need to be set:

Screenshot of App Service Application Settings with Application Insights settings.

Application settings definitions

App setting name	Definition	Value
ApplicationInsightsAgent_EXTENSION_VERSION	Main extension, which controls runtime monitoring.	`~2`
XDT_MicrosoftApplicationInsights_Mode	In default mode, only essential features are enabled in order to insure optimal performance.	`default` or `recommended`.
InstrumentationEngine_EXTENSION_VERSION	Controls if the binary-rewrite engine `InstrumentationEngine` will be turned on. This setting has performance implications and impacts cold start/startup time.	`~1`
XDT_MicrosoftApplicationInsights_BaseExtensions	Controls if SQL & Azure table text will be captured along with the dependency calls. Performance warning: application cold start up time will be affected. This setting requires the `InstrumentationEngine`.	`~1`

App Service Application settings with Azure Resource Manager

Application settings for App Services can be managed and configured with Azure Resource Manager templates. This method can be used when deploying new App Service resources with Azure Resource Manager automation, or for modifying the settings of existing resources.

The basic structure of the application settings JSON for an app service is below:

      "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 an Azure Resource Manager template with Application settings configured for Application Insights, this template can be helpful, specifically the section starting on line 238.

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

To create an Azure Resource Manager template with all the default Application Insights settings configured, begin the process as if you were going to create a new Web App with Application Insights enabled.

Create a new App Service resource with your desired web app information. Enabled Application Insights on the Monitoring tab.
Select Review +create then Download a template for automation at the bottom.

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

Below is a 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": "West US 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

In order to enable the application monitoring through PowerShell, only the underlying application settings need to be changed. Below is a sample, which enables application monitoring for a website called "AppMonitoredSite" in the resource group "AppMonitoredRG", and configures data to be sent to the "012345678-abcd-ef01-2345-6789abcd" instrumentation key.

Note

This article uses the Azure Az PowerShell module, which is the recommended PowerShell module for interacting with Azure. To get started with the Az PowerShell module, see Install Azure PowerShell. To learn how to migrate to the Az PowerShell module, see Migrate Azure PowerShell from AzureRM to Az.

$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

Upgrade from versions 2.8.9 and up

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

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

Screenshot of the URL path to check the version of the extension you are running.

Upgrade from versions 1.0.0 - 2.6.5

Starting with version 2.8.9 the pre-installed site extension is used. If you are 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 Azure App Service installed, the UI shows only Enable button. Behind the scenes, the old private site extension will be removed.)
Upgrade through PowerShell:
1. Set the application settings to enable the pre-installed site extension ApplicationInsightsAgent. 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 ApplicationInsigths dlls are removed from the application bin folder see troubleshooting steps.

Troubleshooting

Note

When you create a web app with the ASP.NET runtimes in Azure App Services it deploys a single static HTML page as a starter website. It is not recommended to troubleshoot an issue with default template. Deploy an application before troubleshooting an issue.

Below is our step-by-step troubleshooting guide for extension/agent based monitoring for ASP.NET based applications running on Azure App Services.

Check that ApplicationInsightsAgent_EXTENSION_VERSION app setting is set to a value of "~2".
Browse to https://yoursitename.scm.azurewebsites.net/ApplicationInsights.
- Confirm that the Application Insights Extension Status is Pre-Installed Site Extension, version 2.8.x.xxxx, is running.
  
  If it is not running, follow the enable Application Insights monitoring instructions.
- Confirm that the status source exists and looks like: Status source D:\home\LogFiles\ApplicationInsights\status\status_RD0003FF0317B6_4248_1.json
  
  If a similar value is not present, it means the application is not currently running or is not supported. To ensure that the application is running, try manually visiting the application url/application endpoints, which will allow the runtime information to become available.
- Confirm that IKeyExists is true If it is false, add APPINSIGHTS_INSTRUMENTATIONKEY and APPLICATIONINSIGHTS_CONNECTION_STRING with your ikey guid to your application settings.
- Confirm that there are no entries for AppAlreadyInstrumented, AppContainsDiagnosticSourceAssembly, and AppContainsAspNetTelemetryCorrelationAssembly.
  
  If any of these entries exist, remove the following packages from your application: Microsoft.ApplicationInsights, System.Diagnostics.DiagnosticSource, and Microsoft.AspNet.TelemetryCorrelation.

Default website deployed with web apps does not support automatic client-side monitoring

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

If you wish to test out codeless server and client-side monitoring for ASP.NET in an Azure App Services web app we recommend following the official guides for creating an ASP.NET Framework web app and then use the instructions in the current article to enable monitoring.

APPINSIGHTS_JAVASCRIPT_ENABLED and urlCompression is not supported

If you use APPINSIGHTS_JAVASCRIPT_ENABLED=true in cases where content is encoded, you might get errors like:

500 URL rewrite error
500.53 URL rewrite module error with message Outbound rewrite rules cannot be applied when the content of the HTTP response is encoded ('gzip').

This is due to the APPINSIGHTS_JAVASCRIPT_ENABLED application setting being set to true and content-encoding being present at the same time. This scenario is not supported yet. The workaround is to remove APPINSIGHTS_JAVASCRIPT_ENABLED from your application settings. Unfortunately this means that if client/browser-side JavaScript instrumentation is still required, manual SDK references are needed for your webpages. Follow the instructions for manual instrumentation with the JavaScript SDK.

For the latest information on the Application Insights agent/extension, check out the release notes.

Connection string and instrumentation key

When codeless monitoring is being used, only the connection string is required. However, we still recommend setting the instrumentation key to preserve backwards compatibility with older versions of the SDK when manual instrumentation is being performed.

Difference between Standard Metrics from Application Insights vs Azure App Service metrics?

Application Insights collects telemetry for those requests which made it to the application. If the failure occurred in WebApps/WebServer, and the request did not reach the user application, then Application Insights will not have any telemetry about it.

The duration for serverresponsetime calculated by Application Insights is not necessarily matching the server response time observed by Web Apps. This is because Application Insights only counts the duration when the request actual reaches user application. If the request is stuck/queued in WebServer, that waiting time will be included in the Web App metrics, but not in Application Insights metrics.

PHP and WordPress are not supported

PHP and WordPress sites are not supported. There is currently no officially supported SDK/agent for server-side monitoring of these workloads. However, manually instrumenting client-side transactions on a PHP or WordPress site by adding the client-side JavaScript to your web pages can be accomplished by using the JavaScript SDK.

The table below provides a more detailed 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 due to a reference to `System.Diagnostics.DiagnosticSource`, `Microsoft.AspNet.TelemetryCorrelation`, or `Microsoft.ApplicationInsights`	Remove the references. Some of these references are added by default from certain Visual Studio templates, and older versions of Visual Studio may add references to `Microsoft.ApplicationInsights`.
`AppAlreadyInstrumented:true`	This value can also be caused by the presence of the above dlls 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: Advanced Tools (Kudu) > Debug console > CMD > home\site\wwwroot).
`AppContainsAspNetTelemetryCorrelationAssembly: true`	This value indicates that extension detected references to `Microsoft.AspNet.TelemetryCorrelation` in the application, and will back-off.	Remove the reference.
`AppContainsDiagnosticSourceAssembly**:true`	This value indicates that extension detected references to `System.Diagnostics.DiagnosticSource` in the application, and will back-off.	For ASP.NET remove the reference.
`IKeyExists:false`	This value indicates that the instrumentation key is not present in the AppSetting, `APPINSIGHTS_INSTRUMENTATIONKEY`. Possible causes: The values may have been accidentally removed, forgot to set the values in automation script, etc.	Make sure the setting is present in the App Service application settings.

Release notes

For the latest updates and bug fixes consult 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 web pages to get client telemetry from the browsers that visit a web page.
Set up Availability web tests to be alerted if your site is down.

Application Monitoring for Azure App Service and ASP.NET

Enable auto-instrumentation monitoring

Enable client-side monitoring

Automate monitoring

Application settings definitions

App Service Application settings with Azure Resource Manager

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

Enable through PowerShell

Upgrade monitoring extension/agent - .NET

Upgrade from versions 2.8.9 and up

Upgrade from versions 1.0.0 - 2.6.5

Troubleshooting

Default website deployed with web apps does not support automatic client-side monitoring

APPINSIGHTS_JAVASCRIPT_ENABLED and urlCompression is not supported

Connection string and instrumentation key

Difference between Standard Metrics from Application Insights vs Azure App Service metrics?

PHP and WordPress are not supported

Release notes

Next steps

Povratne informacije