How to send logs to Application Insights with Serilog and Azure Monitor OpenTelemetry?

Question

I want to see my ASP.NET Core application's logs in Application Insights.

I'm using the following packages:

Azure.Monitor.OpenTelemetry.AspNetCore
Serilog.AspNetCore
Serilog.Sinks.OpenTelemetry

This is the current setup:

builder.Services.AddOpenTelemetry()
    .UseAzureMonitor()
    .ConfigureResource(x =>
    {
        x.AddAttributes(new Dictionary<string, object> { { "service.name", "my-service" } });
    })
    .WithTracing();

builder.Services.AddSerilog((services, lc) => lc
    .ReadFrom.Configuration(builder.Configuration)
    .ReadFrom.Services(services)
    .Enrich.FromLogContext()
    .WriteTo.Console(builder.Environment.IsDevelopment()
        ? new RenderedCompactJsonFormatter()
        : new CompactJsonFormatter())
    .WriteTo.OpenTelemetry()
);

The connection string is passed via the environment variable APPLICATIONINSIGHTS_CONNECTION_STRING. I can see requests in the Application Insights dashboard, but no traces/logs. What's missing here?

Please share your configuration file.

Harshitha Veeramalla
– Harshitha Veeramalla

2025-01-10 17:57:04 +00:00
Commented Jan 10, 2025 at 17:57 — Harshitha Veeramalla
– Harshitha Veeramalla, Commented Jan 10, 2025 at 17:57

mrk · Accepted Answer · 2025-01-10 18:07:37Z

9

UseAzureMonitor calls this under the hood:

builder.Services.AddLogging(
{
    logging.AddOpenTelemetry(builderOptions =>
    {
        builderOptions.IncludeFormattedMessage = true;
    });
});

which in turn registers an <ILoggerProvider, OpenTelemetryLoggerProvider>.

AddSerilog has a default option of writeToProviders = false. If you instead toggle it to true, logs will push through to Application Insights, but it tells you an equivalent Serilog sink should be used instead of writing to all providers.

After toggling that flag, you get double the logs, but I solved that with builder.Logging.ClearProviders();.

I don't know how the library authors intended this integration to look like, but this is my currently working setup:

builder.Logging.ClearProviders();

builder.Services.AddOpenTelemetry()
    .UseAzureMonitor()
    .ConfigureResource(x =>
    {
        x.AddAttributes(new Dictionary<string, object> { { "service.name", "my-service" } });
    });

builder.Services.AddSerilog((services, lc) => lc
    .ReadFrom.Configuration(builder.Configuration)
    .ReadFrom.Services(services)
    .Enrich.FromLogContext()
    .WriteTo.Console(builder.Environment.IsDevelopment()
        ? new RenderedCompactJsonFormatter()
        : new CompactJsonFormatter()), writeToProviders: true);

answered Jan 10, 2025 at 18:07

mrk

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3 Comments

Luminous Over a year ago

I can't believe it's taken me this long to find the solution showing serilog and azure monitor. Everything existing still references the app insights libraries

tHeSiD May 17, 2025 at 15:32

Thank you this worked for me and my setup with the new Azure.Monitor.OpenTelemetry.AspNetCore package

Akash Karve Oct 9, 2025 at 20:19

Thanks, this code works for me as well. But I am not able to get it work using "UseSerilog()" also when I do a structured logging it adding a classname and not making it as actual structured log

Ivan Pavlov · Accepted Answer · 2026-04-02 18:26:33Z

-1

How about Serilog.Sinks.ApplicationInsights package?

It works very well for me.

answered Apr 2 at 18:26

Ivan Pavlov

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2 Comments

jmoerdyk Apr 2 at 18:56

Ivan Pavlov, please don't just post some tool or library as an answer. At least demonstrate how it solves the problem in the answer itself.

Ivan Pavlov 2 days ago

The package itself is the complete solution to the described problem.

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