Metrics examples

This page shows you how to add OpenTelemetry metrics to your project and monitor them.

Add Instrumentation

To add metrics to the project, you need to add some OpenTelemetry nuget packages ( e.g. OpenTelemetry.Extensions.Hosting, OpenTelemetry.Instrumentation.AspNetCore, OpenTelemetry.Exporter.Console). Instrumentation libraries provide metrics (and traces) for the various frameworks and libraries in your project. I'll show some common examples. You can also create an instrumentation by yourself and add custom metrics.

After installing packages, register OpenTelemetry:

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddOpenTelemetry()
    .WithMetrics(x =>
    {
        x.SetResourceBuilder(ResourceBuilder.CreateDefault().AddService(builder.Environment.ApplicationName))
            .AddAspNetCoreInstrumentation()
            .AddRuntimeInstrumentation()
            .AddHttpClientInstrumentation()
            .AddProcessInstrumentation()
            .AddMeter("Microsoft.AspNetCore.Hosting")
            .AddMeter("Microsoft.AspNetCore.Server.Kestrel")
            .AddOtlpExporter();
    })

To watch your metrics, specify the added meters in the Metrics field and click the Watch button (as with EventCounters, you can specify particular metrics for each meter meter-name[metric1,metric2]).

Monitor counters dialog with list of meters

Common Meters

There are two main repositories where you can find some popular instrumentation libraries: OpenTelemetry .NET and OpenTelemetry .NET Contrib. I'll give some examples below, but this is a rapidly developing area and everything can be changed.

ASP.NET Core

From ASP.NET Core 8, there are some built-in metrics. To enable them, add meters Microsoft.AspNetCore.Hosting, Microsoft.AspNetCore.Server.Kestrel and Microsoft.AspNetCore.Http.Connections with AddMeter() method. See the full list of added metrics in this issue.

Meter	Metric	Description
Microsoft.AspNetCore.Hosting	http-server-current-requests	Number of HTTP requests that are currently active on the server
Microsoft.AspNetCore.Hosting	http-server-request-duration	The duration of HTTP requests on the server
Microsoft.AspNetCore.Server.Kestrel	kestrel-current-connections	Number of connections that are currently active on the server
Microsoft.AspNetCore.Server.Kestrel	kestrel-connection-duration	The duration of connections on the server
Microsoft.AspNetCore.Server.Kestrel	kestrel-rejected-connections	Number of connections rejected by the server
Microsoft.AspNetCore.Server.Kestrel	kestrel-queued-connections	Number of connections that are currently queued and are waiting to starter
Microsoft.AspNetCore.Server.Kestrel	kestrel-queued-requests	Number of HTTP requests on multiplexed connections (HTTP/2 and HTTP/3) that are currently queued and are waiting to start
Microsoft.AspNetCore.Server.Kestrel	kestrel-current-upgraded-connections	Number of HTTP connections that are currently upgraded (WebSockets). The number only tracks HTTP/1.1 connections
Microsoft.AspNetCore.Server.Kestrel	kestrel-tls-handshake-duration	The duration of TLS handshakes on the server
Microsoft.AspNetCore.Server.Kestrel	kestrel-current-tls-handshakes	Number of TLS handshakes that are currently in progress on the server
Microsoft.AspNetCore.Http.Connections	signalr-http-transport-current-connections	Number of connections that are currently active on the server
Microsoft.AspNetCore.Http.Connections	signalr-http-transport-current-transports	Number of connection transports that are currently active on the server

OpenTelemetry.Instrumentation.AspNetCore

Link to the repository.

Metric	Description
http.server.duration	Measures the duration of inbound HTTP requests

OpenTelemetry.Instrumentation.Http

Link to the repository

Metric	Description
http.client.duration	Measures the duration of outbound HTTP requests

OpenTelemetry.Instrumentation.Runtime

Link to the repository

Metric	Description
process.runtime.dotnet.gc.collections.count	Number of garbage collections that have occurred since process start
process.runtime.dotnet.gc.objects.size	Count of bytes currently in use by objects in the GC heap that haven't been collected yet
process.runtime.dotnet.gc.allocations.size	Count of bytes allocated on the managed GC heap since the process start
process.runtime.dotnet.gc.committed_memory.size	The amount of committed virtual memory for the managed GC heap, as observed during the latest garbage collection
process.runtime.dotnet.gc.heap.size	The heap size (including fragmentation), as observed during the latest garbage collection
process.runtime.dotnet.gc.heap.fragmentation.size	The heap fragmentation, as observed during the latest garbage collection
process.runtime.dotnet.gc.duration	The total amount of time paused in GC since the process start
process.runtime.dotnet.jit.il_compiled.size	Count of bytes of intermediate language that have been compiled since the process start
process.runtime.dotnet.jit.methods_compiled.count	The number of times the JIT compiler compiled a method since the process start
process.runtime.dotnet.jit.compilation_time	The amount of time the JIT compiler has spent compiling methods since the process start
process.runtime.dotnet.monitor.lock_contention.count	The number of times there was contention when trying to acquire a monitor lock since the process start
process.runtime.dotnet.thread_pool.threads.count	The number of thread pool threads that currently exist
process.runtime.dotnet.thread_pool.completed_items.count	The number of work items that have been processed by the thread pool since the process start
process.runtime.dotnet.thread_pool.queue.length	The number of work items that are currently queued to be processed by the thread pool
process.runtime.dotnet.timer.count	The number of timer instances that are currently active
process.runtime.dotnet.assemblies.count	The number of .NET assemblies that are currently loaded
process.runtime.dotnet.exceptions.count	Count of exceptions that have been thrown in managed code, since the observation started

OpenTelemetry.Instrumentation.Process

Link to the repository

Metric	Description
process.memory.usage	The amount of physical memory allocated for this process
process.memory.virtual	The amount of committed virtual memory for this process
process.cpu.time	Total CPU seconds broken down by states
process.cpu.count	The number of processors (CPU cores) available to the current process
process.threads	Process threads count

OpenTelemetry.Instrumentation.EventCounters

Link to the repository

It's an interesting instrumentation library that enables you to publish your EventCounters as OpenTelemetry metrics.

Last modified: 08 August 2023