Why Application Insights for apps in Azure? - Purpose & Use Cases

The Big Idea

What if you could spot app problems before your users even notice?

The Scenario

Imagine you have a popular app, and users start complaining it crashes or is slow. You try to find the problem by asking users or checking logs manually on each server.

This feels like searching for a needle in a haystack without a magnet.

The Problem

Manually checking logs is slow and confusing. Logs are scattered, hard to read, and you might miss important clues. Fixing issues takes too long, and users get frustrated.

The Solution

Application Insights automatically collects data about your app's performance and errors in one place. It shows clear reports and alerts you when something goes wrong, so you can fix problems fast.

Before vs After

✗ Before

Check logs on each server one by one
Search for errors in text files
Try to guess what caused the crash

✓ After

Enable Application Insights in your app
View performance and error dashboards
Receive alerts for critical issues

What It Enables

It lets you see your app's health and problems instantly, so you can keep users happy and your app running smoothly.

Real Life Example

A game app suddenly slows down after an update. With Application Insights, the developer quickly spots a slow database call causing the lag and fixes it before many players notice.

Key Takeaways

Manual log checking is slow and error-prone.

Application Insights gathers and shows app data automatically.

It helps fix issues quickly and improve user experience.

Practice

1. What is the main purpose of Azure Application Insights?

easy

A. To monitor the health and usage of applications

B. To create virtual machines in Azure

C. To store large amounts of data

D. To manage user identities and access

Solution

1. Step 1: Understand Application Insights role

   Application Insights is designed to monitor apps by collecting data about their performance and usage.

2. Step 2: Compare with other Azure services

   Other options like virtual machines, data storage, or identity management are handled by different Azure services.

3. Final Answer:

   To monitor the health and usage of applications -> Option A

4. Quick Check:

   Monitoring apps = To monitor the health and usage of applications [OK]

Hint: Think monitoring and diagnostics for apps [OK]

Common Mistakes:

• Confusing Application Insights with storage services
• Mixing it up with Azure Active Directory
• Assuming it creates or manages infrastructure

2. Which of the following is the correct way to enable Application Insights in an Azure Web App?

easy

A. Create a virtual machine and install Application Insights manually

B. Add Application Insights SDK and configure instrumentation key

C. Enable Azure Monitor logs only

D. Use Azure Blob Storage to store telemetry data

Solution

1. Step 1: Identify how to enable Application Insights

   Enabling Application Insights requires adding its SDK to the app and setting the instrumentation key for telemetry.

2. Step 2: Eliminate incorrect options

   Creating VMs or using Blob Storage does not enable Application Insights. Azure Monitor logs are related but separate.

3. Final Answer:

   Add Application Insights SDK and configure instrumentation key -> Option B

4. Quick Check:

   SDK + instrumentation key = Add Application Insights SDK and configure instrumentation key [OK]

Hint: SDK plus key enables monitoring [OK]

Common Mistakes:

• Thinking Application Insights runs on VMs only
• Confusing Azure Monitor logs with Application Insights
• Using storage services for telemetry data

3. Given this snippet in an Azure Function app:

var telemetryClient = new TelemetryClient();
telemetryClient.TrackEvent("OrderPlaced");

What will Application Insights record?

medium

A. An error log with message 'OrderPlaced'

B. A performance metric for function execution time

C. An event named 'OrderPlaced' in the telemetry data

D. No data because TelemetryClient is not initialized

Solution

1. Step 1: Understand TrackEvent method

   TrackEvent sends a custom event named as the string argument to Application Insights.

2. Step 2: Check the code behavior

   The code creates a TelemetryClient and tracks an event called 'OrderPlaced', so this event will be recorded.

3. Final Answer:

   An event named 'OrderPlaced' in the telemetry data -> Option C

4. Quick Check:

   TrackEvent sends event = An event named 'OrderPlaced' in the telemetry data [OK]

Hint: TrackEvent logs custom events [OK]

Common Mistakes:

• Assuming TrackEvent logs errors
• Thinking it measures performance automatically
• Believing TelemetryClient needs extra setup to send events

4. You added Application Insights to your app but see no telemetry data in the Azure portal. What is the most likely cause?

medium

A. Application Insights service is not available in your region

B. Azure subscription is expired

C. You need to restart the Azure portal

D. Instrumentation key is missing or incorrect in app configuration

Solution

1. Step 1: Check telemetry data flow requirements

   Telemetry requires the correct instrumentation key configured in the app to send data to Application Insights.

2. Step 2: Evaluate other options

   Subscription expiry or service region issues would cause broader failures, and restarting the portal does not affect telemetry data.

3. Final Answer:

   Instrumentation key is missing or incorrect in app configuration -> Option D

4. Quick Check:

   Missing key blocks telemetry = Instrumentation key is missing or incorrect in app configuration [OK]

Hint: Check instrumentation key first [OK]

Common Mistakes:

• Restarting portal expecting data to appear
• Assuming regional availability blocks telemetry silently
• Ignoring app configuration settings

5. You want to monitor a multi-service app with Application Insights and correlate requests across services. What should you do?

hard

A. Enable distributed tracing and use the same Application Insights resource for all services

B. Create separate Application Insights resources for each service without linking

C. Use Azure Monitor logs only without Application Insights

D. Send telemetry data manually to a storage account

Solution

1. Step 1: Understand distributed tracing in Application Insights

   Distributed tracing allows tracking requests across multiple services by sharing context and using the same Application Insights resource.

2. Step 2: Compare options for multi-service monitoring

   Using separate resources without linking breaks correlation. Azure Monitor logs alone do not provide this tracing. Manual telemetry to storage lacks correlation features.

3. Final Answer:

   Enable distributed tracing and use the same Application Insights resource for all services -> Option A

4. Quick Check:

   Distributed tracing + shared resource = Enable distributed tracing and use the same Application Insights resource for all services [OK]

Hint: Use distributed tracing with shared resource [OK]

Common Mistakes:

• Splitting telemetry into unlinked resources
• Ignoring distributed tracing setup
• Relying only on logs without correlation