Distributed Tracing Across Microservices with Application Insights

Correlate End-to-End Requests

Configuring Application Insights SDK

Distributed tracing in Application Insights works by attaching an operation identifier to every request and passing that identifier from one service to the next. To enable this, you must configure the Application Insights SDK in each microservice of your application. For .NET services, you integrate the SDK with the logging framework, such as ILogger. For services written in other languages, you use the appropriate Azure Monitor exporter or the OpenTelemetry SDK to send trace telemetry. Once configured, the SDK automatically propagates the operation identifier so that all parts of a single request are linked together, even when the request crosses multiple services.

Examining the Application Map

After the SDK is in place, the Application Map in Application Insights provides a visual display of how the services in your system interact. This map shows dependencies between components and lets you reconstruct the exact path a request follows. By examining trace spans—each span represents a unit of work—you can see where the request traveled and which service handled which step. This view makes it easy to spot bottlenecks or unexpected service calls.

Analyzing Telemetry

Detailed telemetry analysis focuses on finding the source of latency and understanding how errors spread through the system. The collected telemetry includes:

• Trace logs: Messages such as debug and info logs that act as breadcrumbs, showing what the application was doing at a specific point in time.
• Custom events and metrics: Manually instrumented data points that highlight significant operations or unusual behavior.

Reviewing trace logs helps during investigations because it adds context around errors, such as what operations were running when a failure occurred.

Best Practices

To get the most value from distributed tracing, collect Information-level logs in production so that enough context is available without overwhelming storage. Ensure each log message carries a contextual identifier, such as the operation ID, which Application Insights attaches automatically. Following these practices gives the team deep visibility into the health and performance of distributed applications and makes it easier to diagnose issues quickly.