OpenTelemetry Injector

The OpenTelemetry injector is a shared library (written in Zig) that is intended to be used via the environment variable LD_PRELOAD, the /etc/ld.so.preload file, or similar mechanisms to inject environment variables into processes at startup.

It serves two main purposes:

• Inject an OpenTelemetry Auto Instrumentation agent into the process to capture and report distributed traces and metrics to the OpenTelemetry Collector for supported runtimes.
• Set resource attributes automatically, (for example Kubernetes related resource attributes and service related resource attributes in environments where this is applicable).

The injector can be used to enable automatic zero-touch instrumentation of processes. For this to work, the injector binary needs to be bundled together with the OpenTelemetry auto-instrumentation agents for the target runtimes.

Official RPM and DEB packages that contain the injector as well as the auto-instrumentation agents are available, and can be downloaded from the releases page. The OpenTelemetry injector Debian/RPM packages install the OpenTelemetry auto-instrumentation agents, the libotelinject.so shared object library, and a default configuration file to automatically instrument applications and services to capture and report distributed traces and metrics to the OpenTelemetry Collector

The opentelemetry-injector deb/rpm package installs and supports configuration of the following Auto Instrumentation agents:

• Java
• Node.js
• .NET

Activation and Configuration

This method requires root privileges.

1. Add the path of the provided /usr/lib/opentelemetry/libotelinject.so shared object library to the /etc/ld.so.preload file to activate Auto Instrumentation for all supported processes on the system. For example:

   echo /usr/lib/opentelemetry/libotelinject.so >> /etc/ld.so.preload
   

   Alternatively, set the environment variable LD_PRELOAD=/usr/lib/opentelemetry/libotelinject.so for a specific process to activate auto-instrumentation for tha process. For example:

   LD_PRELOAD=/usr/lib/opentelemetry/libotelinject.so node myapp.js
   

2. The default configuration file /etc/opentelemetry/otelinject.conf includes the required settings, i.e. the paths to the respective auto-instrumentation agents per runtime:

   dotnet_auto_instrumentation_agent_path_prefix=/usr/lib/opentelemetry/dotnet
   jvm_auto_instrumentation_agent_path=/usr/lib/opentelemetry/javaagent.jar
   nodejs_auto_instrumentation_agent_path=/usr/lib/opentelemetry/otel-js/node_modules/@opentelemetry-js/otel/instrument
   

   There is usually no need to modify this file, unless you want to provide your own instrumentation files.

   However, the configuration file /etc/opentelemetry/otelinject.conf can also be used to selectively disable auto-instrumentation for a specific runtime, by setting the respective path to an empty string. For example, the following file would leave JVM and Node.js auto-instrumentation active, while disabling .NET auto-instrumentation:

   dotnet_auto_instrumentation_agent_path_prefix=
   jvm_auto_instrumentation_agent_path=/usr/lib/opentelemetry/javaagent.jar
   nodejs_auto_instrumentation_agent_path=/usr/lib/opentelemetry/otel-js/node_modules/@opentelemetry-js/otel/instrument
   

   The paths set in /etc/opentelemetry/otelinject.conf can be overridden with environment variables. (This should usually not be necessary.)

   • DOTNET_AUTO_INSTRUMENTATION_AGENT_PATH_PREFIX: the path to the directory containing the .NET Auto Instrumentation agent files
   • JVM_AUTO_INSTRUMENTATION_AGENT_PATH: the path to the Java auto-instrumentation agent JAR file
   • NODEJS_AUTO_INSTRUMENTATION_AGENT_PATH: the path to the Node.js auto-instrumentation agent registration file

   These aforementioned environment variables can also be used to selectively disable auto-instrumentation for a specific runtime, by setting the respective variable to an empty string, that is, set:

   • DOTNET_AUTO_INSTRUMENTATION_AGENT_PATH_PREFIX="" to disable .NET auto-instrumentation
   • JVM_AUTO_INSTRUMENTATION_AGENT_PATH="" to disable JVM auto-instrumentation
   • NODEJS_AUTO_INSTRUMENTATION_AGENT_PATH="" to disable Node.js auto-instrumentation

3. Reboot the system or restart the applications/services for any changes to take effect. The libotelinject.so shared object library will then be preloaded for all subsequent processes and inject the environment variables from the /etc/opentelemetry/otelinject configuration files for Java and Node.js processes.

When providing your own instrumentation files (for example via environment variables like DOTNET_AUTO_INSTRUMENTATION_AGENT_PATH_PREFIX) the following directory structure is expected:

• JVM_AUTO_INSTRUMENTATION_AGENT_PATH: This path must point to the Java auto-instrumentation agent JAR file opentelemetry-javaagent.jar.
• NODEJS_AUTO_INSTRUMENTATION_AGENT_PATH: The path to an installation of the npm module @opentelemetry/auto-instrumentations-node.
• DOTNET_AUTO_INSTRUMENTATION_AGENT_PATH_PREFIX: this path must be a directory that contains the following subdirectories and files:
  • For x86_64 systems using glibc:
    • glibc/linux-x64/OpenTelemetry.AutoInstrumentation.Native.so
    • glibc/AdditionalDeps
    • glibc/store
    • glibc/net/OpenTelemetry.AutoInstrumentation.StartupHook.dll
  • For x86_64 systems using musl:
    • musl/linux-musl-x64/OpenTelemetry.AutoInstrumentation.Native.so
    • musl/AdditionalDeps
    • musl/store
    • musl/net/OpenTelemetry.AutoInstrumentation.StartupHook.dll
  • For arm64 systems using glibc:
    • glibc/linux-arm64/OpenTelemetry.AutoInstrumentation.Native.so
    • glibc/AdditionalDeps
    • glibc/store
    • glibc/net/OpenTelemetry.AutoInstrumentation.StartupHook.dll
  • For arm systems using musl:
    • musl/linux-musl-arm64/OpenTelemetry.AutoInstrumentation.Native.so
    • musl/AdditionalDeps
    • musl/store
    • musl/net/OpenTelemetry.AutoInstrumentation.StartupHook.dll

Note that the defaults provided by the RPM and Debian packages take care of all of that, and it is not necessary to edit /etc/opentelemetry/otelinject.conf or set any of the above environment variables.

Check the following for details about the auto-instrumtation agents and further configuration options:

• Java
• Node.js
• .NET

Contributing

See CONTRIBUTING.md.

Maintainers

• Antoine Toulme, Splunk
• Jacob Aronoff, Omlet
• Michele Mancioppi, Dash0
• Bastian Krol, Dash0

For more information about the maintainer role, see the community repository.