Azure Application Gateway monitoring data reference

This article contains all the monitoring reference information for this service.

See Monitor Azure Application Gateway for details on the data you can collect for Application Gateway and how to use it.

Metrics

This section lists all the automatically collected platform metrics for this service. These metrics are also part of the global list of all platform metrics supported in Azure Monitor.

For information on metric retention, see Azure Monitor Metrics overview.

Supported metrics for Microsoft.Network/applicationGateways

The following table lists the all metrics available for the Microsoft.Network/applicationGateways resource type. More description details for many metrics are included after this table.

• All columns might not be present in every table.
• Some columns might be beyond the viewing area of the page. Select Expand table to view all available columns.

Table headings

• Category - The metrics group or classification.
• Metric - The metric display name as it appears in the Azure portal.
• Name in REST API - The metric name as referred to in the REST API.
• Unit - Unit of measure.
• Aggregation - The default aggregation type. Valid values: Average (Avg), Minimum (Min), Maximum (Max), Total (Sum), Count.
• Dimensions - Dimensions available for the metric.
• Time Grains - Intervals at which the metric is sampled. For example, PT1M indicates that the metric is sampled every minute, PT30M every 30 minutes, PT1H every hour, and so on.
• DS Export- Whether the metric is exportable to Azure Monitor Logs via diagnostic settings. For information on exporting metrics, see Create diagnostic settings in Azure Monitor.

For available Web Application Firewall (WAF) metrics, see Application Gateway WAF v2 metrics and Application Gateway WAF v1 metrics.

Timing metrics for Application Gateway v2 SKU

Application Gateway v2 SKU provides many built‑in timing metrics related to the request and response, which are all measured in milliseconds. What follows is expanded descriptions of the timing metrics already listed in the previous metrics table.

• Backend connect time. This value includes the network latency and the time taken by the backend server's TCP stack to establish new connections. For TLS, it also includes the time spent on handshake.
• Backend first byte response time. This value approximates the sum of Backend connect time, time taken by the request to reach the backend from Application Gateway, time taken by backend application to respond, which is the time the server takes to generate content and potentially fetch database queries, and the time taken by first byte of the response to reach the Application Gateway from the backend.
• Backend last byte response time. This value approximates the sum of backend first byte response time and data transfer time. This number varies greatly depending on the size of objects requested and the latency of the server network.
• Application gateway total time. This interval is the time from Application Gateway receives the first byte of the HTTP request to the time when the last response byte was sent to the client.
• Client RTT. Average round-trip time between clients and Application Gateway.

Metrics for Application Gateway v2 SKU

For Application Gateway v2 SKU, the following metrics are available. What follows is expanded descriptions of the metrics already listed in the previous metrics table.

• Bytes received. This metric accounts for only the Request content size observed by the Application Gateway. It doesn't include data transfers such as TLS header negotiations, TCP/IP packet headers, or retransmissions.
• Bytes sent. This metric accounts for only the Response Content size served by the Application Gateway. It doesn't include data transfers such as TCP/IP packet headers or retransmissions.
• Client TLS protocol. Count of TLS and non-TLS requests.
• Current capacity units. There are three determinants to capacity unit: compute unit, persistent connections, and throughput. Each capacity unit is composed of at most one compute unit, or 2500 persistent connections, or 2.22-Mbps throughput.
• Current compute units. Factors affecting compute unit are TLS connections/sec, URL Rewrite computations, and WAF rule processing.
• Current connections. The total number of concurrent connections active from clients to the Application Gateway.
• Estimated Billed Capacity units. With the v2 SKU, consumption drives the pricing model. Capacity units measure consumption-based cost that is charged in addition to the fixed cost. *Estimated Billed Capacity units indicate the number of capacity units using which the billing is estimated. This amount is calculated as the greater value between Current capacity units (capacity units required to load balance the traffic) and Fixed billable capacity units (minimum capacity units kept provisioned).
• Failed Requests. This value includes the 5xx codes that are generated from the Application Gateway and the 5xx codes that are generated from the backend. The request count can be further filtered to show count per each/specific backend pool-http setting combination.
• Fixed Billable Capacity Units. The minimum number of capacity units kept provisioned as per the Minimum scale units setting in the Application Gateway configuration. One instance translates to 10 capacity units.
• New connections per second. The average number of new TCP connections per second established from clients to the Application Gateway and from the Application Gateway to the backend members.
• Response Status. The response status code distribution can be further categorized to show responses in 2xx, 3xx, 4xx, and 5xx categories.
• Throughput. This metric accounts for only the Content size served by the Application Gateway. It doesn't include data transfers such as TLS header negotiations, TCP/IP packet headers, or retransmissions.
• Total Requests. Successful requests that Application Gateway served. The request count can be filtered to show count per each/specific backend pool-http setting combination.

Backend metrics for Application Gateway v2 SKU

For Application Gateway v2 SKU, the following backend metrics are available. What follows is expanded descriptions of the backend metrics already listed in the previous metrics table.

• Backend response status. Count of HTTP response status codes returned by the backends, not including any response codes generated by the Application Gateway. The response status code distribution can be categorized to show responses in 2xx, 3xx, 4xx, and 5xx categories.|
• Healthy host count. The number of hosts that are determined healthy by the health probe. You can filter on a per backend pool basis to show the number of healthy hosts in a specific backend pool.
• Unhealthy host count. The number of hosts that are determined unhealthy by the health probe. You can filter on a per backend pool basis to show the number of unhealthy hosts in a specific backend pool.
• Requests per minute per Healthy Host. The average number of requests received by each healthy member in a backend pool in a minute. Specify the backend pool using the BackendPool HttpSettings dimension.

Metrics for Application Gateway v1 SKU

For Application Gateway v1 SKU, the following metrics are available. What follows is expanded descriptions of the metrics already listed in the previous metrics table.

• CPU Utilization. Displays the utilization of the CPUs allocated to the Application Gateway. Under normal conditions, CPU usage shouldn't regularly exceed 90%, because that situation might cause latency in the websites hosted behind the Application Gateway and disrupt the client experience. You can indirectly control or improve CPU utilization by modifying the configuration of the Application Gateway by increasing the instance count or by moving to a larger SKU size, or doing both.

• Current connections. Count of current connections established with Application Gateway.

• Failed Requests. Number of requests that failed due to connection issues. This count includes requests that failed due to exceeding the "Request time-out" HTTP setting and requests that failed due to connection issues between Application gateway and backend. This count doesn't include failures due to no healthy backend being available. 4xx and 5xx responses from the backend are also not considered as part of this metric.

• Response Status. HTTP response status returned by Application Gateway. The response status code distribution can be further categorized to show responses in 2xx, 3xx, 4xx, and 5xx categories.

• Throughput. Number of bytes per second the Application Gateway served.

• Total Requests. Count of successful requests that Application Gateway has served. The request count can be further filtered to show count per each/specific backend pool-http setting combination.

Backend metrics for Application Gateway v1 SKU

For Application Gateway v1 SKU, the following backend metrics are available. What follows is expanded descriptions of the backend metrics already listed in the previous metrics table.

• Healthy host count. The number of backends that are determined healthy by the health probe. You can filter on a per backend pool basis to show the number of healthy hosts in a specific backend pool.

• Unhealthy host count. The number of backends that are determined unhealthy by the health probe. You can filter on a per backend pool basis to show the number of unhealthy hosts in a specific backend pool.

Backend health API

See Application Gateways - Backend Health for details of the API call to retrieve the backend health of an application gateway.

Sample Request:

POST
https://management.azure.com/subscriptions/subid/resourceGroups/rg/providers/Microsoft.Network/
applicationGateways/appgw/backendhealth?api-version=2021-08-01

After sending this POST request, you should see an HTTP 202 Accepted response. In the response headers, find the Location header and send a new GET request using that URL.

GET
https://management.azure.com/subscriptions/subid/providers/Microsoft.Network/locations/region-name/operationResults/GUID?api-version=2021-08-01

TLS/TCP proxy metrics

Application Gateway supports TLS/TCP proxy monitoring. With layer 4 proxy feature now available with Application Gateway, there are some Common metrics that apply to both layer 7 and layer 4. There are some layer 4 specific metrics. The following list summarizes the metrics are the applicable for layer 4 usage.

• Current Connections
• New Connections per second
• Throughput
• Healthy host count
• Unhealthy host count
• Client RTT
• Backend Connect Time
• Backend First Byte Response Time. BackendHttpSetting dimension includes both layer 7 and layer 4 backend settings.

For more information, see previous descriptions and the metrics table.

These metrics apply to layer 4 only.

• Backend Session Duration. The total time of a backend connection. The average time duration from the start of a new connection to its termination. BackendHttpSetting dimension includes both layer 7 and layer 4 backend settings.
• Connection Lifetime. The total time of a client connection to application gateway. The average time duration from the start of a new connection to its termination in milliseconds.

TLS/TCP proxy backend health

Application Gateway's layer 4 proxy provides the capability to monitor the health of individual members of the backend pools through the portal and REST API.

Metric dimensions

For information about what metric dimensions are, see Multi-dimensional metrics.

This service has the following dimensions associated with its metrics.

• Action
• BackendHttpSetting
• BackendPool
• BackendServer
• BackendSettingsPool
• Category
• CountryCode
• CustomRuleID
• HttpStatusGroup
• Listener
• Method
• Mode
• PolicyName
• PolicyScope
• RuleGroup
• RuleGroupID
• RuleId
• RuleSetName
• TlsProtocol

Resource logs

This section lists the types of resource logs you can collect for this service. The section pulls from the list of all resource logs category types supported in Azure Monitor.

Supported resource log categories for Microsoft.Network/applicationGateways

• Access log. You can use the Access log to view Application Gateway access patterns and analyze important information. This information includes the caller's IP, requested URL, response latency, return code, and bytes in and out. An access log is collected every 60 seconds. This log contains one record per instance of Application Gateway. The instanceId property identifies the Application Gateway instance.

• Firewall log. You can use the Firewall log to view the requests that are logged through either detection or prevention mode of an application gateway that is configured with the web application firewall. Firewall logs are collected every 60 seconds.

• Performance log. You can use the Performance log to view how Application Gateway instances are performing. This log captures performance information for each instance, including total requests served, throughput in bytes, total requests served, failed request count, and healthy and unhealthy backend instance count. A performance log is collected every 60 seconds.

  Note

  The Performance log is available only for the v1 SKU. For the v2 SKU, use Metrics for performance data.

Access log category

The access log is generated only if you enable it on each Application Gateway instance, as detailed in Enable logging. The data is stored in the storage account that you specified when you enabled the logging. Each access of Application Gateway is logged in JSON format as shown.

For Application Gateway and WAF v2 SKU:

{
    "timeStamp": "2021-10-14T22:17:11+00:00",
    "resourceId": "/SUBSCRIPTIONS/{subscriptionId}/RESOURCEGROUPS/{resourceGroupName}/PROVIDERS/MICROSOFT.NETWORK/APPLICATIONGATEWAYS/{applicationGatewayName}",
    "listenerName": "HTTP-Listener",
    "ruleName": "Storage-Static-Rule",
    "backendPoolName": "StaticStorageAccount",
    "backendSettingName": "StorageStatic-HTTPS-Setting",
    "operationName": "ApplicationGatewayAccess",
    "category": "ApplicationGatewayAccessLog",
    "properties": {
        "instanceId": "appgw_2",
        "clientIP": "185.42.129.24",
        "clientPort": 45057,
        "httpMethod": "GET",
        "originalRequestUriWithArgs": "\/",
        "requestUri": "\/",
        "requestQuery": "",
        "userAgent": "Mozilla\/5.0 (Windows NT 6.1; WOW64) AppleWebKit\/537.36 (KHTML, like Gecko) Chrome\/52.0.2743.116 Safari\/537.36",
        "httpStatus": 200,
        "httpVersion": "HTTP\/1.1",
        "receivedBytes": 184,
        "sentBytes": 466,
        "clientResponseTime": 0,
        "timeTaken": 0.034,
        "WAFEvaluationTime": "0.000",
        "WAFMode": "Detection",
        "transactionId": "592d1649f75a8d480a3c4dc6a975309d",
        "sslEnabled": "on",
        "sslCipher": "ECDHE-RSA-AES256-GCM-SHA384",
        "sslProtocol": "TLSv1.2",
        "sslClientVerify": "NONE",
        "sslClientCertificateFingerprint": "",
        "sslClientCertificateIssuerName": "",
        "serverRouted": "52.239.221.65:443",
        "serverStatus": "200",
        "serverResponseLatency": "0.028",
        "upstreamSourcePort": "21564",
        "originalHost": "20.110.30.194",
        "host": "20.110.30.194",
        "error_info":"ERRORINFO_NO_ERROR",
        "contentType":"application/json"
    }
}

For Application Gateway Standard and WAF SKU (v1):

{
    "resourceId": "/SUBSCRIPTIONS/{subscriptionId}/RESOURCEGROUPS/PEERINGTEST/PROVIDERS/MICROSOFT.NETWORK/APPLICATIONGATEWAYS/{applicationGatewayName}",
    "operationName": "ApplicationGatewayAccess",
    "time": "2017-04-26T19:27:38Z",
    "category": "ApplicationGatewayAccessLog",
    "properties": {
        "instanceId": "ApplicationGatewayRole_IN_0",
        "clientIP": "203.0.113.97",
        "clientPort": 46886,
        "httpMethod": "GET",
        "requestUri": "/phpmyadmin/scripts/setup.php",
        "requestQuery": "X-AzureApplicationGateway-CACHE-HIT=0&SERVER-ROUTED=10.4.0.4&X-AzureApplicationGateway-LOG-ID=aaaa0000-bb11-2222-33cc-444444dddddd&SERVER-STATUS=404",
        "userAgent": "-",
        "httpStatus": 404,
        "httpVersion": "HTTP/1.0",
        "receivedBytes": 65,
        "sentBytes": 553,
        "timeTaken": 205,
        "sslEnabled": "off",
        "host": "www.contoso.com",
        "originalHost": "www.contoso.com"
    }
}

If the application gateway can't complete the request, it stores one of the following reason codes in the error_info field of the access log.

Firewall log category

The firewall log is generated only if you enable it for each application gateway, as detailed in Enable logging. This log also requires that the web application firewall is configured on an application gateway. The data is stored in the storage account that you specified when you enabled the logging. The following data is logged:

{
    "timeStamp": "2021-10-14T22:17:11+00:00",
    "resourceId": "/SUBSCRIPTIONS/{subscriptionId}/RESOURCEGROUPS/{resourceGroupName}/PROVIDERS/MICROSOFT.NETWORK/APPLICATIONGATEWAYS/{applicationGatewayName}",
    "operationName": "ApplicationGatewayFirewall",
    "category": "ApplicationGatewayFirewallLog",
    "properties": {
        "instanceId": "appgw_2",
        "clientIp": "185.42.129.24",
        "clientPort": "",
        "requestUri": "\/",
        "ruleSetType": "OWASP_CRS",
        "ruleSetVersion": "3.0.0",
        "ruleId": "920350",
        "message": "Host header is a numeric IP address",
        "action": "Matched",
        "site": "Global",
        "details": {
            "message": "Warning. Pattern match \\\"^[\\\\d.:]+$\\\" at REQUEST_HEADERS:Host .... ",
            "data": "20.110.30.194:80",
            "file": "rules\/REQUEST-920-PROTOCOL-ENFORCEMENT.conf",
            "line": "791"
        },
        "hostname": "20.110.30.194:80",
        "transactionId": "592d1649f75a8d480a3c4dc6a975309d",
        "policyId": "default",
        "policyScope": "Global",
        "policyScopeName": "Global"
    }
}

Performance log category

The performance log is generated only if you enable it on each Application Gateway instance, as detailed in Enable logging. The data is stored in the storage account that you specified when you enabled the logging. The performance log data is generated in 1-minute intervals. It's available only for the v1 SKU. For the v2 SKU, use Metrics for performance data. The following data is logged:

{
    "resourceId": "/SUBSCRIPTIONS/{subscriptionId}/RESOURCEGROUPS/{resourceGroupName}/PROVIDERS/MICROSOFT.NETWORK/APPLICATIONGATEWAYS/{applicationGatewayName}",
    "operationName": "ApplicationGatewayPerformance",
    "time": "2016-04-09T00:00:00Z",
    "category": "ApplicationGatewayPerformanceLog",
    "properties":
    {
        "instanceId":"ApplicationGatewayRole_IN_1",
        "healthyHostCount":"4",
        "unHealthyHostCount":"0",
        "requestCount":"185",
        "latency":"0",
        "failedRequestCount":"0",
        "throughput":"119427"
    }
}

Azure Monitor Logs and Log Analytics Tables

Azure Application Gateway uses the Azure Diagnostics table to store resource log information. The following columns are relevant.

Azure Monitor Logs tables

This section lists the Azure Monitor Logs tables relevant to this service, which are available for query by Log Analytics using Kusto queries. The tables contain resource log data and possibly more depending on what is collected and routed to them.

Application Gateway Microsoft.Network/applicationGateways

• AzureActivity
• AzureMetrics
• AGWAccessLogs
• AGWPerformanceLogs
• AGWFirewallLogs
• AzureDiagnostics

TLS/TCP proxy logs

Application Gateway's Layer 4 proxy provides log data through access logs. These logs are only generated and published if they're configured in the diagnostic settings of your gateway. Also see: Supported categories for Azure Monitor resource logs.

Activity log

The linked table lists the operations that can be recorded in the activity log for this service. These operations are a subset of all the possible resource provider operations in the activity log.

For more information on the schema of activity log entries, see Activity Log schema.

• applicationGateways resource provider operations

You can use Azure activity logs to view all operations that are submitted to your Azure subscription, and their status. Activity log entries are collected by default. You can view them in the Azure portal. Azure activity logs were formerly known as operational logs and audit logs.

Azure generates activity logs by default. The logs are preserved for 90 days in the Azure event logs store. Learn more about these logs by reading the View events and activity log article.

Related content

• See Monitor Azure Application Gateway for a description of monitoring Application Gateway.
• See Monitor Azure resources with Azure Monitor for details on monitoring Azure resources.