Support Declarative config to override config

[thompson-tomo]

Component(s)

injector

Is your feature request related to a problem? Please describe.

I am wanting to eventually use the injector deployed as part of the otel system package however I am wanting it to use my companies auto-instrumentation agent which is available as a nuget. My company doesn't have any infrastructure or knowledge to be building our own system packages.

Describe the solution you'd like

I would like for the injector to be able to load a declarative config file which has been deployed by opamp to override the current values.

If passing json/yaml has performance implications we could add .conf as a supported declarative config file type.

This solution ensures that we can centrally define a config file which is deployed across the fleet.

Describe alternatives you've considered

Deploying a second config to override that which is installed with the injector package. Issues foreseen is we are changing the paths to the agent what happens with updates? What happens on removal of the agent, how can we update the path?

Additional context

The currently defined overrides are:

• 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
• OTEL_INJECTOR_INCLUDE_PATHS: a comma-separated list of glob patterns to match executable paths
• OTEL_INJECTOR_EXCLUDE_PATHS: a comma-separated list of glob patterns to exclude executable paths
• OTEL_INJECTOR_INCLUDE_WITH_ARGUMENTS: a comma-separated list of glob patterns to match process arguments
• OTEL_INJECTOR_EXCLUDE_WITH_ARGUMENTS: a comma-separated list of glob patterns to exclude process arguments
• OTEL_INJECTOR_AUTO_INSTRUMENTATION_DISABLED: either * to disable all auto-instrumentation for all runtimes, or a comma-separated list of runtimes for which to disable auto-instrumentation

Tip

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[grcevski]

We have an environment variable that allows you to specify where the injector configuration file is, OTEL_INJECTOR_CONFIG_FILE and also to change the default directory for the config files OTEL_INJECTOR_CONFIG_DIR.

Would this work for you? This way you can manipulate the configuration for the injector via remote file management protocols.

[thompson-tomo]

We have an environment variable that allows you to specify where the injector configuration file is, OTEL_INJECTOR_CONFIG_FILE and also to change the default directory for the config files OTEL_INJECTOR_CONFIG_DIR.

Would this work for you? This way you can manipulate the configuration for the injector via remote file management protocols.

No as that requires the variable to have been set & hence managed going forward. the key thing with this issue is the injector would now be able to use a declarative config file.

[jack-berg]

No as that requires the variable to have been set

You can set any OTEL_* prefixed env var in /etc/opentelemetry/injector/default_env.conf and they will be injected into any process which matches the injector's include/exclude criteria: https://github.com/open-telemetry/opentelemetry-injector/blame/5b70fa09855e0b3919aa143f97c10c3e9ce6b0df/README.md#L83-L94

So the idea is to add OTEL_CONFIG_FILE to /etc/opentelemetry/injector/default_env.conf