.NET Core

Use OpenTelemetry to automatically instrument your .NET application and send telemetry data to Last9 without modifying your application code.

Prerequisites

• .NET SDK 8.0 or later

Installation

1. Install OpenTelemetry .NET Auto-Instrumentation

   Download and install the auto-instrumentation agent:

   • Linux/macOS
   • Windows

   # Download the installation script
   curl -sSfL https://github.com/open-telemetry/opentelemetry-dotnet-instrumentation/releases/latest/download/otel-dotnet-auto-install.sh -O
   
   # Make it executable and run
   chmod +x otel-dotnet-auto-install.sh
   ./otel-dotnet-auto-install.sh

2. Verify Installation

   Check that the installation was successful:

   • Linux/macOS
   • Windows

   # Verify installation directory exists
   ls -la $HOME/.otel-dotnet-auto
   
   # Check for key files
   ls -la $HOME/.otel-dotnet-auto/instrument.sh
   ls -la $HOME/.otel-dotnet-auto/net/

Setup Auto-Instrumentation

Environment Variables

Set the required environment variables for Last9. Replace the placeholder values with your actual Last9 configuration:

export OTEL_DOTNET_AUTO_INSTRUMENTATION_ENABLED=true
export OTEL_SERVICE_NAME="<your_service_name>"
export OTEL_TRACES_EXPORTER=otlp
export OTEL_EXPORTER_OTLP_ENDPOINT="{{ .Logs.WriteURL }}"
export OTEL_EXPORTER_OTLP_HEADERS="Authorization={{ .Logs.AuthValue }}"
export OTEL_TRACES_SAMPLER="always_on"
export OTEL_LOG_LEVEL=error
export OTEL_RESOURCE_ATTRIBUTES="deployment.environment=local"

$env:OTEL_DOTNET_AUTO_INSTRUMENTATION_ENABLED="true"
$env:OTEL_SERVICE_NAME="<your_service_name>"
$env:OTEL_TRACES_EXPORTER="otlp"
$env:OTEL_EXPORTER_OTLP_ENDPOINT="{{ .Logs.WriteURL }}"
$env:OTEL_EXPORTER_OTLP_HEADERS="Authorization={{ .Logs.AuthValue }}"
$env:OTEL_TRACES_SAMPLER="always_on"
$env:OTEL_LOG_LEVEL="error"
$env:OTEL_RESOURCE_ATTRIBUTES="deployment.environment=local"

Source the Instrumentation Script

Before running your application, source the instrumentation script:

Application Code

Minimal Application Setup

With auto-instrumentation, your application code requires no OpenTelemetry-specific packages or configuration. Keep your Program.cs clean.

Project File (.csproj)

Your project file should be minimal - no OpenTelemetry packages needed:

<Project Sdk="Microsoft.NET.Sdk.Web">
  <PropertyGroup>
    <TargetFramework>net8.0</TargetFramework>
    <Nullable>enable</Nullable>
    <ImplicitUsings>enable</ImplicitUsings>
    <RootNamespace>MyDotNetApi</RootNamespace>
  </PropertyGroup>
</Project>

Running Your Application

Complete Startup Script

Create a startup script that sets up everything:

#!/bin/bash

# Set OpenTelemetry environment variables

export OTEL_DOTNET_AUTO_INSTRUMENTATION_ENABLED=true
export OTEL_SERVICE_NAME="<your_service_name>"
export OTEL_TRACES_EXPORTER=otlp
export OTEL_EXPORTER_OTLP_ENDPOINT="{{ .Logs.WriteURL }}"
export OTEL_EXPORTER_OTLP_HEADERS="Authorization={{ .Logs.AuthValue }}"
export OTEL_TRACES_SAMPLER="always_on"
export OTEL_LOG_LEVEL=error
export OTEL_RESOURCE_ATTRIBUTES="deployment.environment=local"

echo "Starting .NET application with OpenTelemetry auto-instrumentation..."
echo "Service Name: $OTEL_SERVICE_NAME"
echo "OTLP Endpoint: $OTEL_EXPORTER_OTLP_ENDPOINT"

# Source the auto-instrumentation

. $HOME/.otel-dotnet-auto/instrument.sh

# Build and run the application

dotnet build --configuration Release
dotnet run --configuration Release

@echo off

REM Set OpenTelemetry environment variables
set OTEL_DOTNET_AUTO_INSTRUMENTATION_ENABLED=true
set OTEL_SERVICE_NAME="<your_service_name>"
set OTEL_TRACES_EXPORTER=otlp
set OTEL_EXPORTER_OTLP_ENDPOINT="{{ .Logs.WriteURL }}"
set OTEL_EXPORTER_OTLP_HEADERS="Authorization={{ .Logs.AuthValue }}"
set OTEL_TRACES_SAMPLER=always_on

echo Starting .NET application with OpenTelemetry auto-instrumentation...
echo Service Name: %OTEL_SERVICE_NAME%
echo OTLP Endpoint: %OTEL_EXPORTER_OTLP_ENDPOINT%

REM Source the auto-instrumentation
call "%USERPROFILE%\.otel-dotnet-auto\instrument.cmd"

REM Build and run the application
dotnet build --configuration Release
dotnet run --configuration Release

Verify Telemetry

You should see debug output in your console showing:

• OpenTelemetry initialization
• Span creation for HTTP requests
• Trace export attempts to Last9

What Gets Automatically Instrumented

The auto-instrumentation automatically captures:

• HTTP requests (ASP.NET Core)
• Database calls (Entity Framework, SQL Client, MongoDB, etc.)
• HTTP client calls (HttpClient)
• Message queues (RabbitMQ, Azure Service Bus, etc.)
• Custom logs via ILogger
• gRPC calls
• Redis operations

Advanced Configuration

Custom Resource Attributes

Add additional resource attributes to identify your service better:

export OTEL_RESOURCE_ATTRIBUTES="service.name=my-dotnet-api,deployment.environment=production,service.version=1.2.3"

Disable Specific Instrumentations

Disable instrumentations you don’t need:

export OTEL_DOTNET_AUTO_INSTRUMENTATION_ASPNETCORE_ENABLED=true
export OTEL_DOTNET_AUTO_INSTRUMENTATION_HTTPCLIENT_ENABLED=true
export OTEL_DOTNET_AUTO_INSTRUMENTATION_SQLCLIENT_ENABLED=false

Once you run your application with the proper environment setup, it will automatically start sending telemetry data to Last9.