OpenTelemetry .NET Automatic Instrumentation

This project adds OpenTelemetry instrumentation to .NET applications without having to modify their source code.

Warning

The following documentation refers to the in-development version of OpenTelemetry .NET Automatic Instrumentation. Docs for the latest version (1.8.0) can be found in opentelemetry.io or here.

Quick start

If you'd like to try the instrumentation on an existing application before learning more about the configuration options and the project, use the recommended installation method described at Using the OpenTelemetry.AutoInstrumentation NuGet packages or use the appropriate install script:

On Linux and macOS, use the shell scripts.
On Windows, use the PowerShell module.

Note

The NuGet packages are the recommended way to deploy automatic instrumentation, but they can't be used in all cases. See Limitations for details.

To see the telemetry from your application directly on the standard output, set the following environment variables to console before launching your application:

OTEL_TRACES_EXPORTER
OTEL_METRICS_EXPORTER
OTEL_LOGS_EXPORTER

For a demo using docker compose, clone this repository and follow the examples/demo/README.md.

Components

OpenTelemetry .NET Automatic Instrumentation is built on top of OpenTelemetry .NET:

Core components: 1.9.0
System.Diagnostics.DiagnosticSource: 8.0.0 referencing System.Runtime.CompilerServices.Unsafe: 6.0.0

You can find all references in OpenTelemetry.AutoInstrumentation.csproj and OpenTelemetry.AutoInstrumentation.AdditionalDeps/Directory.Build.props.

To automatically instrument applications, the OpenTelemetry .NET Automatic Instrumentation does the following:

Injects and configures the OpenTelemetry .NET SDK into the application.
Adds OpenTelemetry Instrumentation to key packages and APIs used by the application.

You can enable the OpenTelemetry .NET Automatic Instrumentation as a .NET Profiler to inject additional instrumentations of this project at runtime, using a technique known as monkey-patching. When enabled, the OpenTelemetry .NET Automatic Instrumentation generates traces for libraries that don't already generate traces using the OpenTelemetry .NET SDK.

See design.md for an architectural overview.

Status

The versioning information and stability guarantees can be found in the versioning documentation.

Compatibility

OpenTelemetry .NET Automatic Instrumentation should work with all officially supported operating systems and versions of .NET.

The minimal supported version of .NET Framework is 4.6.2.

Supported processor architectures are:

x86
AMD64 (x86-64)
ARM64 (Experimental)

Note

ARM64 build does not support CentOS based images.

CI tests run against the following operating systems:

Instrumented libraries and frameworks

See config.md#instrumented-libraries-and-frameworks.

Get started

Considerations on scope

Instrumenting self-contained applications is supported through NuGet packages. Note that a self-contained application is automatically generated in .NET 7+ whenever the dotnet publish or dotnet build command is used with a Runtime Identifier (RID) parameter, for example when -r or --runtime is used when running the command.

Install using NuGet packages

The NuGet packages are the recommended way to deploy automatic instrumentation, but they can't be used in all cases. To install using the NuGet packages, see Using the OpenTelemetry.AutoInstrumentation NuGet packages. See Limitations for incompatible scenarios.

Install manually

To install the automatic instrumentation manually, download and extract the appropriate binaries from the latest release.

Note

The path where you put the binaries is referenced as $INSTALL_DIR.

Instrument a .NET application

When running your application, make sure to:

Set the resources.
Set the environment variables from the table below.

Environment variable	.NET version	Value
`COR_ENABLE_PROFILING`	.NET Framework	`1`
`COR_PROFILER`	.NET Framework	`{918728DD-259F-4A6A-AC2B-B85E1B658318}`
`COR_PROFILER_PATH_32`	.NET Framework	`$INSTALL_DIR/win-x86/OpenTelemetry.AutoInstrumentation.Native.dll`
`COR_PROFILER_PATH_64`	.NET Framework	`$INSTALL_DIR/win-x64/OpenTelemetry.AutoInstrumentation.Native.dll`
`CORECLR_ENABLE_PROFILING`	.NET	`1`
`CORECLR_PROFILER`	.NET	`{918728DD-259F-4A6A-AC2B-B85E1B658318}`
`CORECLR_PROFILER_PATH`	.NET on Linux glibc	`$INSTALL_DIR/linux-x64/OpenTelemetry.AutoInstrumentation.Native.so`
`CORECLR_PROFILER_PATH`	.NET on Linux musl	`$INSTALL_DIR/linux-musl-x64/OpenTelemetry.AutoInstrumentation.Native.so`
`CORECLR_PROFILER_PATH`	.NET on macOS	`$INSTALL_DIR/osx-x64/OpenTelemetry.AutoInstrumentation.Native.dylib`
`CORECLR_PROFILER_PATH_32`	.NET on Windows	`$INSTALL_DIR/win-x86/OpenTelemetry.AutoInstrumentation.Native.dll`
`CORECLR_PROFILER_PATH_64`	.NET on Windows	`$INSTALL_DIR/win-x64/OpenTelemetry.AutoInstrumentation.Native.dll`
`DOTNET_ADDITIONAL_DEPS`	.NET	`$INSTALL_DIR/AdditionalDeps`
`DOTNET_SHARED_STORE`	.NET	`$INSTALL_DIR/store`
`DOTNET_STARTUP_HOOKS`	.NET	`$INSTALL_DIR/net/OpenTelemetry.AutoInstrumentation.StartupHook.dll`
`OTEL_DOTNET_AUTO_HOME`	All versions	`$INSTALL_DIR`

Note

Some settings can be omitted on .NET. For more information, see config.md.

Important

Starting in .NET 8, the environment variable DOTNET_EnableDiagnostics=0 disables all diagnostics, including the CLR Profiler facility which is needed to launch the instrumentation, if not using .NET Startup hooks. Ensure that DOTNET_EnableDiagnostics=1, or if you'd like to limit diagnostics only to the CLR Profiler, you may set both DOTNET_EnableDiagnostics=1 and DOTNET_EnableDiagnostics_Profiler=1 while setting other diagnostics features to 0. See this issue for more guidance.

Shell scripts

You can install OpenTelemetry .NET Automatic Instrumentation and instrument your .NET application using the provided Shell scripts.

Note

On macOS coreutils is required.

Example usage:

# Download the bash script
curl -sSfL https://github.com/open-telemetry/opentelemetry-dotnet-instrumentation/releases/download/v1.8.0/otel-dotnet-auto-install.sh -O

# Install core files
sh ./otel-dotnet-auto-install.sh

# Enable execution for the instrumentation script
chmod +x $HOME/.otel-dotnet-auto/instrument.sh

# Setup the instrumentation for the current shell session
. $HOME/.otel-dotnet-auto/instrument.sh

# Run your application with instrumentation
OTEL_SERVICE_NAME=myapp OTEL_RESOURCE_ATTRIBUTES=deployment.environment=staging,service.version=1.0.0 ./MyNetApp

NOTE: for air-gapped environments you can provide either the installation archive directly with:

LOCAL_PATH=<PATH_TO_ARCHIVE> sh ./otel-dotnet-auto-install.sh

or the folder with the archives, this has the added benefit that the install script will determine the correct archive to choose.

DOWNLOAD_DIR=<PATH_TO_FOLDER_WITH_ARCHIVES> sh ./otel-dotnet-auto-install.sh

otel-dotnet-auto-install.sh script uses environment variables as parameters:

Parameter	Description	Required	Default value
`OTEL_DOTNET_AUTO_HOME`	Location where binaries are to be installed	No	`$HOME/.otel-dotnet-auto`
`OS_TYPE`	Possible values: `linux-glibc`, `linux-musl`, `macos`, `windows`	No	Calculated
`ARCHITECTURE`	Possible values for Linux: `x64`, `arm64`	No	Calculated
`TMPDIR`	(deprecated) prefer `DOWNLOAD_DIR`	No	`$(mktemp -d)`
`DOWNLOAD_DIR`	Folder to download the archive to. Will use local archive if it already exists	No	`$TMPDIR` or `$(mktemp -d)`
`LOCAL_PATH`	Full path the archive to use for installation. (ideal for air-gapped scenarios)	No	Calculated
`VERSION`	Version to download	No	`1.8.0`

instrument.sh script uses environment variables as parameters:

Parameter	Description	Required	Default value
`ENABLE_PROFILING`	Whether to set the .NET CLR Profiler, possible values: `true`, `false`	No	`true`
`OTEL_DOTNET_AUTO_HOME`	Location where binaries are to be installed	No	`$HOME/.otel-dotnet-auto`
`OS_TYPE`	Possible values: `linux-glibc`, `linux-musl`, `macos`, `windows`	No	Calculated
`ARCHITECTURE`	Possible values for Linux: `x64`, `arm64`	No	Calculated

PowerShell module (Windows)

On Windows, you should install OpenTelemetry .NET Automatic Instrumentation and instrument your .NET application using the provided PowerShell module. Example usage (run as administrator):

# Download the module
$module_url = "https://github.com/open-telemetry/opentelemetry-dotnet-instrumentation/releases/download/v1.8.0/OpenTelemetry.DotNet.Auto.psm1"
$download_path = Join-Path $env:temp "OpenTelemetry.DotNet.Auto.psm1"
Invoke-WebRequest -Uri $module_url -OutFile $download_path -UseBasicParsing

# Import the module to use its functions
Import-Module $download_path

# Install core files (online vs offline method)
Install-OpenTelemetryCore
Install-OpenTelemetryCore -LocalPath "C:\Path\To\OpenTelemetry.zip" 

# Set up the instrumentation for the current PowerShell session
Register-OpenTelemetryForCurrentSession -OTelServiceName "MyServiceDisplayName"

# Run your application with instrumentation
.\MyNetApp.exe

You can get usage information by calling:

# List all available commands
Get-Command -Module OpenTelemetry.DotNet.Auto

# Get command's usage information
Get-Help Install-OpenTelemetryCore -Detailed

Updating OpenTelemetry installation:

# Import the previously downloaded module. After an update the module is found in the default install directory.
# Note: It's best to use the same version of the module for installation and uninstallation to ensure proper removal.
Import-Module "C:\Program Files\OpenTelemetry .NET AutoInstrumentation\OpenTelemetry.DotNet.Auto.psm1"

# If IIS was previously registered, use RegisterIIS = $true.
Update-OpenTelemetryCore -RegisterIIS $true

# If Windows services were previously registered, these must be re-registered manually.
Unregister-OpenTelemetryForWindowsService -WindowsServiceName MyServiceName
Update-OpenTelemetryCore
Register-OpenTelemetryForWindowsService -WindowsServiceName MyServiceName -OTelServiceName MyOtelServiceName