Application performance monitoring
APM Tips
Instrument, query, alert. Field notes for production monitoring.
Practical guides for Azure Monitor Application Insights and OpenTelemetry, explained KQL, and calculators for sampling and cost. Every guide opens with the answer and dates its sources.
Start here
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Hub
Application Insights
Configuration and troubleshooting for Azure Monitor Application Insights, for the classic SDK and the OpenTelemetry distros that replace it.
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Library
KQL library
Explained, copy-paste queries for the Application Insights tables: latency percentiles, failures, slow dependencies, all sampling-aware.
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Tools
Tools
A sampling and ingestion cost calculator and a KQL query builder, each showing how it arrives at its figures.
Latest guides
All guides →-
Application Insights
Agent-based dependency tracking: what the Application Insights Agent sees and misses
How the Application Insights Agent collects SQL and HTTP dependencies on IIS, when the instrumentation engine is needed, and what still needs code.
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Application Insights
App Service auto-instrumentation vs the SDK: which one to run
What Application Insights auto-instrumentation collects on App Service, Functions, AKS and IIS, when to move to code, and why one collector per app is enough.
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Application Insights
Application Insights pricing: what you pay for, and how to cut the bill
Application Insights bills by the GB its Log Analytics workspace ingests. Current East US prices, the free allowance and retention, and what to change first.
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Application Insights
ApplicationInsights.config: do you still need it, and what replaced it
What ApplicationInsights.config controls, which apps still read it, and where its settings went in SDK 3.x and the Microsoft OpenTelemetry Distro.
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Application Insights
Application Insights for ASP.NET MVC and Web API on .NET Framework
What still works for ASP.NET MVC and Web API on .NET Framework, the HTTP modules, unhandled vs handled exceptions, trace forwarding, and the SDK 3.x upgrade.
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Application Insights
Azure Monitor alerts explained: log alerts, action groups and the alert email
What an Azure Monitor alert email means, metric vs log search alerts, action groups, a log alert over KQL step by step, what alerts cost, and how to stop noise.
Latest queries
KQL library →-
Apdex-style satisfaction score per operation
requests latency
Returns: One row per operation with its request count, the satisfied, tolerating and frustrated counts against the target, and a 0-to-1 score, worst first.
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Availability results by test and location
availabilityResults availability
Returns: One row per availability test and test location with the number of runs, the failed runs, the availability percentage and the p95 test duration in milliseconds, worst first.
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Availability test failures with their messages
availabilityResults availability
Returns: Up to 100 failed availability test runs from the last 24 hours, newest first, each with the test name, location, duration in milliseconds, failure message and operation_Id.