Monitor Azure Load Balancer

  • Article

This article describes:

  • The types of monitoring data you can collect for this service.
  • How to analyze that data.

Note

If you're already familiar with this service and/or Azure Monitor and just want to know how to analyze monitoring data, see the Analyze section near the end of this article.

When you have critical applications and business processes that rely on Azure resources, you need to monitor and get alerts for your system. The Azure Monitor service collects and aggregates metrics and logs from every component of your system. Azure Monitor provides you with a view of availability, performance, and resilience, and notifies you of issues. You can use the Azure portal, PowerShell, Azure CLI, REST API, or client libraries to set up and view monitoring data.

Load Balancer provides other monitoring data through:

https://docs.azure.cn/azure-monitor/logs/logs-ingestion-api-overview

Insights

Some services in Azure have a built-in monitoring dashboard in the Azure portal that provides a starting point for monitoring your service. These dashboards are called insights, and you can find them in the Insights Hub of Azure Monitor in the Azure portal.

Load Balancer insights provide:

  • Functional dependency view
  • Metrics dashboard
  • Overview tab
  • Frontend and Backend Availability tab
  • Data Throughput tab
  • Flow Distribution
  • Connection Monitors
  • Metric Definitions

For more information on Load Balancer insights, see Using Insights to monitor and configure your Azure Load Balancer.

Resource types

Azure uses the concept of resource types and IDs to identify everything in a subscription. Azure Monitor similarly organizes core monitoring data into metrics and logs based on resource types, also called namespaces. Different metrics and logs are available for different resource types. Your service might be associated with more than one resource type.

Resource types are also part of the resource IDs for every resource running in Azure. For example, one resource type for a virtual machine is Microsoft.Compute/virtualMachines. For a list of services and their associated resource types, see Resource providers.

For more information about the resource types for Load Balancer, see Azure Load Balancer monitoring data reference.

Data storage

For Azure Monitor:

  • Metrics data is stored in the Azure Monitor metrics database.
  • Log data is stored in the Azure Monitor logs store. Log Analytics is a tool in the Azure portal that can query this store.
  • The Azure activity log is a separate store with its own interface in the Azure portal.
  • You can optionally route metric and activity log data to the Azure Monitor logs database store so you can query the data and correlate it with other log data using Log Analytics.

For detailed information on how Azure Monitor stores data, see Azure Monitor data platform.

Azure Monitor platform metrics

Azure Monitor provides platform metrics for most services. These metrics are:

  • Individually defined for each namespace.
  • Stored in the Azure Monitor time-series metrics database.
  • Lightweight and capable of supporting near real-time alerting.
  • Used to track the performance of a resource over time.

Collection: Azure Monitor collects platform metrics automatically. No configuration is required.

Routing: You can also usually route platform metrics to Azure Monitor logs / Log Analytics so you can query them with other log data. For more information, see the Metrics diagnostic setting. For how to configure diagnostic settings for a service, see Create diagnostic settings in Azure Monitor.

For a list of all metrics it's possible to gather for all resources in Azure Monitor, see Supported metrics in Azure Monitor.

You can analyze metrics for Load Balancer with metrics from other Azure services using metrics explorer by opening Metrics from the Azure Monitor menu. See Analyze metrics with Azure Monitor metrics explorer for details on using this tool.

For a list of available metrics for Load Balancer, see Azure Load Balancer monitoring data reference.

Azure Monitor resource logs

Resource logs provide insight into operations that were done by an Azure resource. Logs are generated automatically, but you must route them to Azure Monitor logs to save or query them. Logs are organized by category. A given namespace might have multiple resource log categories.

Collection: Resource logs aren't collected and stored until you create a diagnostic setting and route the logs to one or more locations. When you create a diagnostic setting, you specify which categories of logs to collect. There are multiple ways to create and maintain diagnostic settings, including the Azure portal, programmatically, and though Azure Policy.

Routing: The suggested default is to route resource logs to Azure Monitor Logs so you can query them with other log data. Other locations such as Azure Storage, Azure Event Hubs, and certain Azure monitoring partners are also available. For more information, see Azure resource logs and Resource log destinations.

For detailed information about collecting, storing, and routing resource logs, see Diagnostic settings in Azure Monitor.

For a list of all available resource log categories in Azure Monitor, see Supported resource logs in Azure Monitor.

All resource logs in Azure Monitor have the same header fields, followed by service-specific fields. The common schema is outlined in Azure Monitor resource log schema.

For the available resource log categories, their associated Log Analytics tables, and the log schemas for Load Balancer, see Azure Load Balancer monitoring data reference.

Creating a diagnostic setting

Resource logs aren't collected and stored until you create a diagnostic setting and route them to one or more locations. You can create a diagnostic setting with the Azure portal, Azure PowerShell, or the Azure CLI.

To use the Azure portal and for general guidance, see Create diagnostic setting to collect platform logs and metrics in Azure. To use PowerShell or the Azure CLI, see the following sections.

When you create a diagnostic setting, you specify which categories of logs to collect. The category for Load Balancer is AllMetrics.

PowerShell

Sign in to Azure PowerShell:

Connect-AzAccount -Environment AzureChinaCloud

Log analytics workspace

To send resource logs to a Log Analytics workspace, enter these commands. Replace the bracketed values with your values:

## Place the load balancer in a variable. ##
$lbpara = @{
    ResourceGroupName = <your-resource-group-name>
    Name = <your-load-balancer-name>
}
$lb = Get-AzLoadBalancer @lbpara

## Place the workspace in a variable. ##
$wspara = @{
    ResourceGroupName = <your-resource-group-name>
    Name = <your-log-analytics-workspace-name>
}
$ws = Get-AzOperationalInsightsWorkspace @wspara

## Enable the diagnostic setting. ##
Set-AzDiagnosticSetting `
    -ResourceId $lb.id `
    -Name <your-diagnostic-setting-name> `
    -Enabled $true `
    -MetricCategory 'AllMetrics' `
    -WorkspaceId $ws.ResourceId

Storage account

To send resource logs to a storage account, enter these commands. Replace the bracketed values with your values:

## Place the load balancer in a variable. ##
$lbpara = @{
    ResourceGroupName = <your-resource-group-name>
    Name = <your-load-balancer-name>
}
$lb = Get-AzLoadBalancer @lbpara

## Place the storage account in a variable. ##
$storpara = @{
    ResourceGroupName = <your-resource-group-name>
    Name = <your-storage-account-name>
}
$storage = Get-AzStorageAccount @storpara

## Enable the diagnostic setting. ##
Set-AzDiagnosticSetting `
    -ResourceId $lb.id `
    -Name <your-diagnostic-setting-name> `
    -StorageAccountId $storage.id `
    -Enabled $true `
    -MetricCategory 'AllMetrics'

Event hub

To send resource logs to an event hub namespace, enter these commands. Replace the bracketed values with your values:

## Place the load balancer in a variable. ##
$lbpara = @{
    ResourceGroupName = <your-resource-group-name>
    Name = <your-load-balancer-name>
}
$lb = Get-AzLoadBalancer @lbpara

## Place the event hub in a variable. ##
$hubpara = @{
    ResourceGroupName = <your-resource-group-name>
    Name = <your-event-hub-name>
}
$eventhub = Get-AzEventHubNamespace @hubpara

## Place the event hub authorization rule in a variable. ##    
$hubrule = @{
    ResourceGroupName = 'myResourceGroup'
    Namespace = 'myeventhub8675'
}
$eventhubrule = Get-AzEventHubAuthorizationRule @hubrule

## Enable the diagnostic setting. ##
Set-AzDiagnosticSetting `
    -ResourceId $lb.Id `
    -Name 'myDiagSetting-event'`
    -EventHubName $eventhub.Name `
    -EventHubAuthorizationRuleId $eventhubrule.Id `
    -Enabled $true `
    -MetricCategory 'AllMetrics'

Azure CLI

Sign in to Azure CLI:

az cloud set -n AzureChinaCloud
az login
# az cloud set -n AzureCloud   //means return to Public Azure.

Log analytics workspace

To send resource logs to a Log Analytics workspace, enter these commands. Replace the bracketed values with your values:

lbid=$(az network lb show \
    --name <your-load-balancer-name> \
    --resource-group <your-resource-group> \
    --query id \
    --output tsv)

wsid=$(az monitor log-analytics workspace show \
    --resource-group <your-resource-group> \
    --workspace-name <your-log-analytics-workspace-name> \
    --query id \
    --output tsv)

az monitor diagnostic-settings create \
    --name <your-diagnostic-setting-name> \
    --resource $lbid \
    --metrics '[{"category": "AllMetrics","enabled": true}]' \
    --workspace $wsid

Storage account

To send resource logs to a storage account, enter these commands. Replace the bracketed values with your values:

lbid=$(az network lb show \
    --name <your-load-balancer-name> \
    --resource-group <your-resource-group> \
    --query id \
    --output tsv)

storid=$(az storage account show \
        --name <your-storage-account-name> \
        --resource-group <your-resource-group> \
        --query id \
        --output tsv)

az monitor diagnostic-settings create \
    --name <your-diagnostic-setting-name> \
    --resource $lbid \
    --metrics '[{"category": "AllMetrics","enabled": true}]' \
    --storage-account $storid

Event hub

To send resource logs to an event hub namespace, enter these commands. Replace the bracketed values with your values:

lbid=$(az network lb show \
    --name <your-load-balancer-name> \
    --resource-group <your-resource-group> \
    --query id \
    --output tsv)

az monitor diagnostic-settings create \
    --name myDiagSetting-event \
    --resource $lbid \
    --metrics '[{"category": "AllMetrics","enabled": true}]' \
    --event-hub-rule /subscriptions/<your-subscription-id>/resourceGroups/<your-resource-group>/providers/Microsoft.EventHub/namespaces/<your-event-hub-namespace>/authorizationrules/RootManageSharedAccessKey

Azure activity log

The activity log contains subscription-level events that track operations for each Azure resource as seen from outside that resource; for example, creating a new resource or starting a virtual machine.

Collection: Activity log events are automatically generated and collected in a separate store for viewing in the Azure portal.

Routing: You can send activity log data to Azure Monitor Logs so you can analyze it alongside other log data. Other locations such as Azure Storage, Azure Event Hubs, and certain Azure monitoring partners are also available. For more information on how to route the activity log, see Overview of the Azure activity log.

Analyze monitoring data

There are many tools for analyzing monitoring data.

Azure Monitor tools

Azure Monitor supports the following basic tools:

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.
  • 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.

Azure Monitor export tools

You can get data out of Azure Monitor into other tools by using the following methods:

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

Analyzing Load Balancer Traffic with NSG flow logs

NSG flow logs is a feature of Azure Network Watcher that allows you to log information about IP traffic flowing through a network security group. Flow data is sent to Azure Storage from where you can access it and export it to a visualization tool, security information and event management (SIEM) solution, or intrusion detection system (IDS).

NSG flow logs can be used to analyze traffic flowing through the load balancer.

Note

NSG flow logs don't contain the load balancers frontend IP address. To analyze the traffic flowing into a load balancer, the NSG flow logs would need to be filtered by the private IP addresses of the load balancer's backend pool members.

Kusto queries

You can analyze monitoring data in the Azure Monitor Logs / Log Analytics store by using the Kusto query language (KQL).

Important

When you select Logs from the service's menu in the portal, Log Analytics opens with the query scope set to the current service. This scope means that log queries will only include data from that type of resource. If you want to run a query that includes data from other Azure services, select Logs from the Azure Monitor menu. See Log query scope and time range in Azure Monitor Log Analytics for details.

For a list of common queries for any service, see the Log Analytics queries interface.

Alerts

Azure Monitor alerts proactively notify you when specific conditions are found in your monitoring data. Alerts allow you to identify and address issues in your system before your customers notice them. For more information, see Azure Monitor alerts.

There are many sources of common alerts for Azure resources. For examples of common alerts for Azure resources, see Sample log alert queries. The Azure Monitor Baseline Alerts (AMBA) site provides key alert metrics, dashboards, and guidelines for Azure Landing Zone (ALZ) scenarios.

The common alert schema standardizes the consumption of Azure Monitor alert notifications. For more information, see Common alert schema.

Types of alerts

You can alert on any metric or log data source in the Azure Monitor data platform. There are many different types of alerts depending on the services you're monitoring and the monitoring data you're collecting. Different types of alerts have various benefits and drawbacks. For more information, see Choose the right monitoring alert type.

The following list describes the types of Azure Monitor alerts you can create:

  • Metric alerts evaluate resource metrics at regular intervals. Metrics can be platform metrics, custom metrics, logs from Azure Monitor converted to metrics, or Application Insights metrics. Metric alerts can also apply multiple conditions and dynamic thresholds.
  • Log alerts allow users to use a Log Analytics query to evaluate resource logs at a predefined frequency.
  • Activity log alerts trigger when a new activity log event occurs that matches defined conditions. Resource Health alerts and Service Health alerts are activity log alerts that report on your service and resource health.

You can also create the following types of alerts for some Azure services:

  • Smart detection alerts on an Application Insights resource automatically warn you of potential performance problems and failure anomalies in your web application. You can migrate smart detection on your Application Insights resource to create alert rules for the different smart detection modules.
  • Prometheus alerts alert on Prometheus metrics stored in Azure Monitor managed services for Prometheus . The alert rules are based on the PromQL open-source query language. Your service may not support this type of alert. Currently, Prometheus is used on a limited set of services with a guest operating system, such as Azure Virtual Machine and Azure Container Instances.
  • Recommended alert rules are available out-of-box for some Azure resources, including virtual machines, Azure Kubernetes Service (AKS) resources, and Log Analytics workspaces.

Monitor multiple resources

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. Individual notifications are sent for each monitored resource. For supported Azure services and clouds, see Monitor multiple resources with one alert rule.

Note

If you're creating or running an application that runs on your service, Azure Monitor application insights might offer more types of alerts.

Load Balancer alert rules

The following table lists some suggested alert rules for Load Balancer. These alerts are just examples. You can set alerts for any metric, log entry, or activity log entry listed in the Azure Load Balancer monitoring data reference.

Alert type Condition Description
Load balancing rule unavailable due to unavailable VMs If data path availability split by Frontend IP address and Frontend Port (all known and future values) is equal to zero, or in a second independent alert, if health probe status is equal to zero, then fire alerts These alerts help determine if the data path availability for any configured load balancing rules isn't servicing traffic due to all VMs in the associated backend pool being probed down by the configured health probe. Review load balancer troubleshooting guide to investigate the potential root cause.
VM availability significantly low If health probe status split by Backend IP and Backend Port is equal to user defined probed-up percentage of total pool size (that is, 25% are probed up), then fire alert This alert determines if there are less than needed VMs available to serve traffic
Outbound connections to internet endpoint failing If SNAT Connection Count filtered to Connection State = Failed is greater than zero, then fire alert This alert fires when SNAT ports are exhausted and VMs are failing to initiate outbound connections.
Approaching SNAT exhaustion If Used SNAT Ports is greater than user defined number, then fire alert This alert requires a static outbound configuration where the same number of ports are always allocated. It then fires when a percentage of the allocated ports is used.

Advisor recommendations

If critical conditions or imminent changes occur during resource operations, an alert displays on the Overview page in the portal.

You can find more information and recommended fixes for the alert in Advisor recommendations under Monitoring. During normal operations, no advisor recommendations display.

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

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