Monitor Azure Front Door

Azure Monitor collects and aggregates metrics and logs from your system to monitor availability, performance, and resilience, and notify you of issues affecting your system. You can use the Azure portal, PowerShell, Azure CLI, REST API, or client libraries to set up and view monitoring data.

Different metrics and logs are available for different resource types. This article describes the types of monitoring data you can collect for this service and ways to analyze that data.

Collect data with Azure Monitor

This table describes how you can collect data to monitor your service, and what you can do with the data once collected:

For the list of all of the data supported by Azure Monitor, see:

• Azure Monitor supported metrics

Built-in monitoring for Azure Front Door

Logs track all requests that pass through Azure Front Door. It can take a few minutes for logs to be processed and stored.

There are multiple Front Door logs, which you can use for different purposes:

• Access logs can be used to identify slow requests, determine error rates, and understand how Front Door's caching behavior is working for your solution.
• Health probe logs can be used to identify origins that are unhealthy or that don't respond to requests from some of Front Door's geographically distributed PoPs.
• Activity logs provide visibility into the operations performed on your Azure resources, such as configuration changes to your Azure Front Door profile.

Access log

Information about every request is logged into the access log. Each access log entry contains the information listed in the following table.

Health probe log

Azure Front Door logs every failed health probe request. These logs can help you to diagnose problems with an origin. The logs provide you with information that you can use to investigate the failure reason and then bring the origin back to a healthy status.

Some scenarios this log can be useful for are:

• You noticed Azure Front Door traffic was sent to a subset of the origins. For example, you might notice that only three out of four origins receive traffic. You want to know if the origins are receiving and responding to health probes so you know whether the origins are healthy.
• You noticed the origin health percentage metric is lower than you expected. You want to know which origins are recorded as unhealthy and the reason for the health probe failures.

Each health probe log entry has the following schema:

The following example JSON snippet shows a health probe log entry for a failed health probe request.

{
  "records": [
    {
      "time": "2021-02-02T07:15:37.3640748Z",
      "resourceId": "/SUBSCRIPTIONS/mySubscriptionID/RESOURCEGROUPS/myResourceGroup/PROVIDERS/MICROSOFT.CDN/PROFILES/MyProfile",
      "category": "FrontDoorHealthProbeLog",
      "operationName": "Microsoft.Cdn/Profiles/FrontDoorHealthProbeLog/Write",
      "properties": {
        "healthProbeId": "9642AEA07BA64675A0A7AD214ACF746E",
        "POP": "MAA",
        "httpVerb": "HEAD",
        "result": "OriginError",
        "httpStatusCode": "400",
        "probeURL": "http://www.example.com:80/",
        "originName": "www.example.com",
        "originIP": "PublicI:Port",
        "totalLatencyMilliseconds": "141",
        "connectionLatencyMilliseconds": "68",
        "DNSLatencyMicroseconds": "1814"
      }
    }
  ]
}

Use Azure Monitor tools to analyze the data

These Azure Monitor tools are available in the Azure portal to help you analyze monitoring data:

• Some Azure services have a built-in monitoring dashboard in the Azure portal. These dashboards are called insights, and you can find them in the Insights section of Azure Monitor in the Azure portal.

• Metrics explorer allows you to view and analyze metrics for Azure resources. For more information, see Analyze metrics with Azure Monitor metrics explorer.

• Log Analytics allows you to query and analyze log data using the Kusto query language (KQL). For more information, see Get started with log queries in Azure Monitor.

• The Azure portal has a user interface for viewing and basic searches of the activity log. To do more in-depth analysis, route the data to Azure Monitor logs and run more complex queries in Log Analytics.

• Application Insights monitors the availability, performance, and usage of your web applications, so you can identify and diagnose errors without waiting for a user to report them.
  Application Insights includes connection points to various development tools and integrates with Visual Studio to support your DevOps processes. For more information, see Application monitoring for App Service.

Tools that allow more complex visualization include:

• Dashboards that let you combine different kinds of data into a single pane in the Azure portal.
• Workbooks, customizable reports that you can create in the Azure portal. Workbooks can include text, metrics, and log queries.
• Grafana, an open platform tool that excels in operational dashboards. You can use Grafana to create dashboards that include data from multiple sources other than Azure Monitor.
• Power BI, a business analytics service that provides interactive visualizations across various data sources. You can configure Power BI to automatically import log data from Azure Monitor to take advantage of these visualizations.

Export Azure Monitor data

You can export data out of Azure Monitor into other tools using:

• Metrics: Use the REST API for metrics to extract metric data from the Azure Monitor metrics database. For more information, see Azure Monitor REST API reference.

• Logs: Use the REST API or the associated client libraries.

• The Log Analytics workspace data export.

To get started with the Azure Monitor REST API, see Azure monitoring REST API walkthrough.

Use Kusto queries to analyze log data

You can analyze Azure Monitor Log data using the Kusto query language (KQL). For more information, see Log queries in Azure Monitor.

Use Azure Monitor alerts to notify you of issues

Azure Monitor alerts allow you to identify and address issues in your system, and proactively notify you when specific conditions are found in your monitoring data before your customers notice them. You can alert on any metric or log data source in the Azure Monitor data platform. There are different types of Azure Monitor alerts depending on the services you're monitoring and the monitoring data you're collecting. See Choosing the right type of alert rule.

For examples of common alerts for Azure resources, see Sample log alert queries.

Implementing alerts at scale

For some services, you can monitor at scale by applying the same metric alert rule to multiple resources of the same type that exist in the same Azure region. Azure Monitor Baseline Alerts (AMBA) provides a semi-automated method of implementing important platform metric alerts, dashboards, and guidelines at scale.

Get personalized recommendations using Azure Advisor

For some services, if critical conditions or imminent changes occur during resource operations, an alert displays on the service Overview page in the portal. You can find more information and recommended fixes for the alert in Advisor recommendations under Monitoring in the left menu. During normal operations, no advisor recommendations display.

For more information on Azure Advisor, see Azure Advisor overview.

Related content

• Azure Front Door monitoring data reference
• Monitoring Azure resources with Azure Monitor