Getting Started with Application Insights

What Is Application Insights?

Azure Application Insights is an extensible Application Performance Management (APM) service within Azure Monitor. It provides deep monitoring for live applications, helping you detect anomalies, diagnose issues, and understand usage patterns.

Official Documentation: Application Insights overview

Core Capabilities

Capability	Description
Request Tracking	Monitor incoming requests, response times, and failure rates
Dependency Tracking	Track calls to databases, REST APIs, and Azure services
Exception Tracking	Capture and analyse unhandled exceptions and errors
Distributed Tracing	End-to-end trace correlation across microservices
Application Map	Visual map of service dependencies and health
Live Metrics	Real-time performance and diagnostic data
Availability Tests	Synthetic monitoring from global locations
User Analytics	Usage patterns, user flows, and retention
Custom Events/Metrics	Application-specific telemetry
Smart Detection	AI-powered anomaly detection and alerting

Architecture

Logic Apps → Application Insights → Log Analytics Workspace
APIM       →                     →
Functions  →                     → Azure Monitor
App Service →                    → Alerts → Action Groups → Teams/Email/PagerDuty

Workspace-Based vs Classic

Application Insights now uses workspace-based mode (classic is deprecated):

Microsoft Reference: Workspace-based Application Insights

Setting Up Application Insights

Create via Bicep

param location string = resourceGroup().location
param environment string

// Log Analytics Workspace (required for workspace-based App Insights)
resource logAnalyticsWorkspace 'Microsoft.OperationalInsights/workspaces@2022-10-01' = {
  name: 'log-integration-${environment}'
  location: location
  properties: {
    sku: {
      name: 'PerGB2018'
    }
    retentionInDays: environment == 'prod' ? 90 : 30
    features: {
      enableLogAccessUsingOnlyResourcePermissions: true
    }
    workspaceCapping: {
      dailyQuotaGb: environment == 'prod' ? 10 : 1
    }
  }
}

// Application Insights
resource appInsights 'Microsoft.Insights/components@2020-02-02' = {
  name: 'appi-integration-${environment}'
  location: location
  kind: 'web'
  properties: {
    Application_Type: 'web'
    WorkspaceResourceId: logAnalyticsWorkspace.id
    RetentionInDays: environment == 'prod' ? 90 : 30
    IngestionMode: 'LogAnalytics'
    publicNetworkAccessForIngestion: 'Enabled'
    publicNetworkAccessForQuery: 'Enabled'
  }
  tags: {
    environment: environment
    service: 'integration-platform'
  }
}

output appInsightsConnectionString string = appInsights.properties.ConnectionString
output appInsightsInstrumentationKey string = appInsights.properties.InstrumentationKey
output workspaceId string = logAnalyticsWorkspace.id

Create via Azure CLI

# Create Log Analytics Workspace
az monitor log-analytics workspace create \
  --resource-group rg-integration-prod \
  --workspace-name log-integration-prod \
  --location uksouth \
  --retention-time 90 \
  --sku PerGB2018

# Create Application Insights (workspace-based)
az monitor app-insights component create \
  --app appi-integration-prod \
  --resource-group rg-integration-prod \
  --location uksouth \
  --kind web \
  --workspace log-integration-prod \
  --retention-time 90

Connecting Azure Services

Logic Apps (Standard)

Add the Application Insights connection string to your Logic App app settings:

resource logicApp 'Microsoft.Web/sites@2022-09-01' = {
  // ...
  properties: {
    siteConfig: {
      appSettings: [
        {
          name: 'APPLICATIONINSIGHTS_CONNECTION_STRING'
          value: appInsights.properties.ConnectionString
        }
        {
          name: 'APPINSIGHTS_INSTRUMENTATIONKEY'
          value: appInsights.properties.InstrumentationKey
        }
      ]
    }
  }
}

Logic Apps (Consumption)

Enable diagnostic settings to send telemetry:

resource logicAppDiagnostics 'Microsoft.Insights/diagnosticSettings@2021-05-01-preview' = {
  name: 'la-diagnostics'
  scope: logicApp
  properties: {
    workspaceId: logAnalyticsWorkspace.id
    logs: [
      {
        category: 'WorkflowRuntime'
        enabled: true
        retentionPolicy: { enabled: true, days: 90 }
      }
    ]
    metrics: [
      {
        category: 'AllMetrics'
        enabled: true
        retentionPolicy: { enabled: true, days: 30 }
      }
    ]
  }
}

API Management

resource apimLogger 'Microsoft.ApiManagement/service/loggers@2023-05-01-preview' = {
  parent: apim
  name: 'appinsights-logger'
  properties: {
    loggerType: 'applicationInsights'
    resourceId: appInsights.id
    credentials: {
      connectionString: appInsights.properties.ConnectionString
    }
  }
}

resource apimDiagnostic 'Microsoft.ApiManagement/service/diagnostics@2023-05-01-preview' = {
  parent: apim
  name: 'applicationinsights'
  properties: {
    loggerId: apimLogger.id
    alwaysLog: 'allErrors'
    sampling: {
      samplingType: 'fixed'
      percentage: 25
    }
    httpCorrelationProtocol: 'W3C'
  }
}

Azure Functions

resource functionApp 'Microsoft.Web/sites@2022-09-01' = {
  // ...
  properties: {
    siteConfig: {
      appSettings: [
        {
          name: 'APPLICATIONINSIGHTS_CONNECTION_STRING'
          value: appInsights.properties.ConnectionString
        }
      ]
    }
  }
}

Microsoft Reference: Enable Application Insights

Telemetry Types

Type	Description	Example
Request	Incoming HTTP requests	API call to Logic App
Dependency	Outgoing calls to external services	SQL query, HTTP call, Service Bus
Exception	Unhandled errors	NullReferenceException, timeout
Trace	Diagnostic log messages	"Processing order ORD-001"
Event	Custom business events	"OrderCompleted", "PaymentProcessed"
Metric	Custom numeric measurements	"OrderTotal", "ProcessingTime"
PageView	Developer portal page loads	"API documentation viewed"
Availability	Synthetic test results	"Health check passed"

Connection String vs Instrumentation Key

Always use Connection String (Instrumentation Key is deprecated):

# Connection String format
InstrumentationKey=abc123;IngestionEndpoint=https://uksouth-1.in.applicationinsights.azure.com/;LiveEndpoint=https://uksouth.livediagnostics.monitor.azure.com/

# Instrumentation Key (deprecated, for backwards compatibility)
APPINSIGHTS_INSTRUMENTATIONKEY=abc123

Microsoft Reference: Connection strings

Sampling

Sampling reduces telemetry volume (and cost) while maintaining statistical accuracy:

Types of Sampling

Type	Description	Configuration
Adaptive	Automatically adjusts rate	Default for server-side SDKs
Fixed-rate	Fixed percentage of telemetry	Configured in Application Insights
Ingestion	Filters at the service endpoint	Portal setting

Configure Sampling

// host.json for Logic Apps Standard / Azure Functions
{
  "logging": {
    "applicationInsights": {
      "samplingSettings": {
        "isEnabled": true,
        "maxTelemetryItemsPerSecond": 20,
        "evaluationInterval": "01:00:00",
        "initialSamplingPercentage": 100,
        "minSamplingPercentage": 0.1,
        "maxSamplingPercentage": 100,
        "movingAverageRatio": 1,
        "excludedTypes": "Exception;Event",
        "includedTypes": ""
      }
    }
  }
}

Important: Always exclude Exception and Event types from sampling to ensure all errors and business events are captured.

Availability Tests

Monitor endpoint availability from multiple global locations:

URL Ping Test

resource availabilityTest 'Microsoft.Insights/webtests@2022-06-15' = {
  name: 'webtest-api-health'
  location: location
  kind: 'ping'
  tags: {
    'hidden-link:${appInsights.id}': 'Resource'
  }
  properties: {
    SyntheticMonitorId: 'webtest-api-health'
    Name: 'API Health Check'
    Enabled: true
    Frequency: 300  // 5 minutes
    Timeout: 30
    Kind: 'ping'
    RetryEnabled: true
    Locations: [
      { Id: 'emea-gb-db3-azr' }   // UK South
      { Id: 'emea-nl-ams-azr' }   // Netherlands
      { Id: 'us-va-ash-azr' }     // US East
    ]
    Configuration: {
      WebTest: '<WebTest Name="API Health" Url="https://apim-enterprise-prod.azure-api.net/health" Timeout="30" />'
    }
  }
}

Standard Test (Multi-Step)

Standard tests support:

• SSL certificate validation
• Custom headers
• Request body
• Response content validation
• Multiple request steps

Microsoft Reference: Availability tests

Cost Management

Pricing Model

Application Insights charges based on data ingestion:

Component	Cost
Data ingestion	~£2.30 per GB
Data retention	Free for first 90 days, then ~£0.10 per GB/month
Availability tests	Free for up to 10 tests
Daily cap	Configurable limit on daily ingestion

Cost Control Strategies

1. Set daily caps — Prevent unexpected cost spikes
2. Use sampling — Reduce ingestion volume while maintaining accuracy
3. Configure retention — Use shorter retention for non-production
4. Filter telemetry — Exclude health checks and internal traffic
5. Monitor ingestion volume — Set alerts on daily GB ingested

// Set daily cap
resource logAnalyticsWorkspace 'Microsoft.OperationalInsights/workspaces@2022-10-01' = {
  // ...
  properties: {
    workspaceCapping: {
      dailyQuotaGb: 5  // 5 GB daily limit
    }
  }
}

Naming Conventions

appi-{workload}-{environment}     // Application Insights
log-{workload}-{environment}      // Log Analytics Workspace

Examples:

• appi-integration-prod / log-integration-prod
• appi-api-platform-dev / log-api-platform-dev

Best Practices

1. Use workspace-based Application Insights (classic is deprecated)
2. Share a Log Analytics workspace across related services for cross-resource queries
3. Configure sampling in production to balance visibility and cost
4. Exclude exceptions from sampling to capture all errors
5. Use Connection String instead of Instrumentation Key
6. Set daily ingestion caps to prevent cost overruns
7. Enable diagnostic settings on all Azure resources (Logic Apps, APIM, Functions)
8. Use W3C correlation for distributed tracing across services
9. Create availability tests for critical API endpoints
10. Tag resources consistently for cost tracking and organisation

Official Microsoft Resources

• Application Insights overview
• Workspace-based Application Insights
• Sampling in Application Insights
• Application Insights pricing
• Connection strings
• Availability tests
• Azure Monitor overview