Application Insights
What it is
Application Insights is an Application Performance Monitoring (APM) feature of Azure Monitor that collects application-level telemetry — requests, dependencies, exceptions, page views, traces — from live apps (web apps, functions, APIs, mobile). It’s the application observability layer, complementing platform infrastructure metrics.
Why it exists
Infrastructure monitoring (CPU, disk) tells you the host is fine but not why users are frustrated. Application Insights instruments the app itself to reveal request latency, error rates, failed dependencies (DBs, external APIs), and end-to-end distributed traces — the insight you need for debugging performance.
Key ideas
- Instrument apps with the SDK (or agentless for certain PaaS) sending telemetry to an Application Insights workspace (backed by Log Analytics).
- Signals: requests, dependencies, exceptions, traces, metrics, availability tests (URL ping from global locations).
- Rich views: Application Map (visual service dependencies), Live Metrics, Profiler/Snapshot Debugger (paid).
- Data stored in a Log Analytics workspace — query with KQL, feed workbooks and alerts.
- Availability / URL ping tests are a key monitoring feature.
How it fits (diagram)
Diagrams courtesy of Microsoft Learn / Azure docs: azure-monitor/app/app-insights-overview
Exam notes
- App Insights = application (code) telemetry; Azure Monitor metrics/logs = infrastructure/platform telemetry.
- Data lives in a Log Analytics workspace and is KQL-queryable.
- Availability tests (ping from global locations) check a URL’s reachability — often a question topic.
- Instrument the app, not just the host.
Related
azure-monitor · log-analytics · kql · metric-alert · workbooks · Home
📘 Source: Microsoft Learn — Application Insights