Send .NET Serilog Logs to SigNoz Using OpenTelemetry

This guide shows how to send logs from a .NET application to SigNoz. The application must use the Serilog logging library. The setup uses the official Serilog.Sinks.OpenTelemetry sink. This sink sends logs directly over OTLP, so it does not need the OpenTelemetry .NET SDK.

Prerequisites

• A supported .NET version or .NET Framework 4.6.2 or later
• A .NET application that already logs with Serilog
• An instance of SigNoz (either Cloud or Self-Hosted)

Send logs to SigNoz

Step 1: Install the sink

Add the Serilog.Sinks.OpenTelemetry package to your project:

dotnet add package Serilog.Sinks.OpenTelemetry

This installs the latest version. If your project pins an older version, upgrade to v4.0.0 or later. Earlier versions ignore OTEL_SERVICE_NAME and the other OTEL_EXPORTER_OTLP_* environment variables used in Step 3.

Step 2: Configure the sink

Add the OpenTelemetry sink to your Serilog logger configuration. Do this where you build Log.Logger, usually at the start of Program.cs. Leave out the endpoint, protocol, and headers here. The sink reads them from environment variables at startup:

using Serilog;
 
Log.Logger = new LoggerConfiguration()
    .WriteTo.Console()
    .WriteTo.OpenTelemetry()
    .CreateLogger();
 
try
{
    // Your application code
}
finally
{
    Log.CloseAndFlush();
}

This works in any .NET application, including .NET Framework 4.6.2 and later.

dotnet add package Serilog.AspNetCore

var builder = WebApplication.CreateBuilder(args);
builder.Host.UseSerilog();
 
var app = builder.Build();
app.Run();

using Serilog;
using Serilog.Sinks.OpenTelemetry;
 
Log.Logger = new LoggerConfiguration()
    .WriteTo.Console()
    .WriteTo.OpenTelemetry(options =>
    {
        options.Endpoint = "https://ingest.<region>.signoz.cloud:443";
        options.Protocol = OtlpProtocol.HttpProtobuf;
        options.Headers = new Dictionary<string, string>
        {
            ["signoz-ingestion-key"] = "<your-ingestion-key>"
        };
        options.ResourceAttributes = new Dictionary<string, object>
        {
            ["service.name"] = "<service_name>"
        };
    })
    .CreateLogger();

Step 3: Set environment variables and run

export OTEL_EXPORTER_OTLP_PROTOCOL="http/protobuf"
export OTEL_EXPORTER_OTLP_ENDPOINT="https://ingest.<region>.signoz.cloud:443"
export OTEL_EXPORTER_OTLP_HEADERS="signoz-ingestion-key=<your-ingestion-key>"
export OTEL_SERVICE_NAME="<service_name>"
dotnet run

env:
  - name: OTEL_EXPORTER_OTLP_PROTOCOL
    value: 'http/protobuf'
  - name: OTEL_EXPORTER_OTLP_ENDPOINT
    value: 'https://ingest.<region>.signoz.cloud:443'
  - name: OTEL_EXPORTER_OTLP_HEADERS
    value: 'signoz-ingestion-key=<your-ingestion-key>'
  - name: OTEL_SERVICE_NAME
    value: '<service_name>'

kubectl apply -f <deployment-file>.yaml
kubectl rollout restart deployment/<deployment-name>

ENV OTEL_EXPORTER_OTLP_PROTOCOL="http/protobuf"
ENV OTEL_EXPORTER_OTLP_ENDPOINT="https://ingest.<region>.signoz.cloud:443"
ENV OTEL_EXPORTER_OTLP_HEADERS="signoz-ingestion-key=<your-ingestion-key>"
ENV OTEL_SERVICE_NAME="<service_name>"

docker build -t <image-name> .
docker run <image-name>

$env:OTEL_EXPORTER_OTLP_PROTOCOL = "http/protobuf"
$env:OTEL_EXPORTER_OTLP_ENDPOINT = "https://ingest.<region>.signoz.cloud:443"
$env:OTEL_EXPORTER_OTLP_HEADERS = "signoz-ingestion-key=<your-ingestion-key>"
$env:OTEL_SERVICE_NAME = "<service_name>"
dotnet run

Correlate logs with traces

The sink adds trace_id and span_id to each log record from the current Activity. This happens automatically and needs no extra code.

For this correlation to work, your application must also send traces to SigNoz. Follow the .NET tracing guide to set up an AddOtlpExporter trace pipeline alongside this log sink.

System.Diagnostics.Activity.DefaultIdFormat = System.Diagnostics.ActivityIdFormat.W3C;

options.OnBeginSuppressInstrumentation = OpenTelemetry.SuppressInstrumentationScope.Begin;

Validate

1. Generate some log activity in your application.
2. Open SigNoz and go to Logs.
3. Filter by your service.name to find your log records.

Next Steps

• .NET traces instrumentation guide
• Log Query/Filtering guides
• Alerts setup for logs

Get Help

If you need help with the steps in this topic, please reach out to us on SigNoz Community Slack. If you are a SigNoz Cloud user, please use in product chat support located at the bottom right corner of your SigNoz instance or contact us at cloud-support@signoz.io.