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 (once the first relase has been published). 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

The following methods are supported to manually activate and configure Auto Instrumentation after installation of the opentelemetry-injector deb/rpm package (requires root privileges):

• System-wide
• Systemd services only

Note: To prevent conflicts and duplicate traces/metrics, only one method should be activated on the target system.

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

Note: The following steps utilize a sample systemd drop-in file to activate/configure the provided agents for all systemd services via default environment variables. Systemd supports many options, methods, and paths for configuring environment variables at the system level or for individual services, and are not limited to the steps below. Before making any changes, it is recommended to consult the documentation specific to your Linux distribution or service, and check the existing configurations of the system and individual services for potential conflicts or to override an environment variable for a particular service. For general details about systemd, see the systemd man page.

1. Copy the provided sample systemd drop-in file /usr/lib/opentelemetry/examples/systemd/00-otelinject-instrumentation.conf to the host's systemd drop-in configuration directory to activate Auto Instrumentation for all supported applications running as systemd services. For example:

   mkdir -p /usr/lib/systemd/system.conf.d/ && cp /usr/lib/opentelemetry/examples/systemd/00-otelinject-instrumentation.conf /usr/lib/systemd/system.conf.d/
   

   This file includes the required environment variables to activate the respective agents with the default options:
   • Java:

     DefaultEnvironment="JAVA_TOOL_OPTIONS=-javaagent:/usr/lib/opentelemetry/otel-javaagent.jar"
     

   • Node.js:

     DefaultEnvironment="NODE_OPTIONS=-r /usr/lib/opentelemetry/otel-js/node_modules/@opentelemetry/auto-instrumentations-node/register"
     

   • .NET

     DefaultEnvironment="CORECLR_ENABLE_PROFILING=1"
     DefaultEnvironment="CORECLR_PROFILER={918728DD-259F-4A6A-AC2B-B85E1B658318}"
     DefaultEnvironment="CORECLR_PROFILER_PATH=/usr/lib/opentelemetry/otel-dotnet/linux-x64/OpenTelemetry.AutoInstrumentation.Native.so"
     DefaultEnvironment="DOTNET_ADDITIONAL_DEPS=/usr/lib/opentelemetry/otel-dotnet/AdditionalDeps"
     DefaultEnvironment="DOTNET_SHARED_STORE=/usr/lib/opentelemetry/otel-dotnet/store"
     DefaultEnvironment="DOTNET_STARTUP_HOOKS=/usr/lib/opentelemetry/otel-dotnet/net/OpenTelemetry.AutoInstrumentation.StartupHook.dll"
     DefaultEnvironment="OTEL_DOTNET_AUTO_HOME=/usr/lib/opentelemetry/otel-dotnet"
     

2. To configure the activated agents, add/update DefaultEnvironment within the target file from the previous step for the desired environment variables. For example:

   cat <<EOH >> /usr/lib/systemd/system.conf.d/00-otelinject-instrumentation.conf
   DefaultEnvironment="OTEL_EXPORTER_OTLP_ENDPOINT=http://127.0.0.1:4317"
   DefaultEnvironment="OTEL_RESOURCE_ATTRIBUTES=deployment.environment=my_deployment_environment"
   DefaultEnvironment="OTEL_SERVICE_NAME=my_service_name"
   EOH
   

   Check the following for all supported environment variables and default values:
   • Java
   • Node.js
   • .NET
3. Reboot the system, or run systemctl daemon-reload and then restart the applicable systemd services for any changes to take effect.

See CONTRIBUTING.md.

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

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