OpenTelemetry SDK components are highly configurable. This specification outlines the mechanisms by which OpenTelemetry components can be configured. It does not attempt to specify the details of what can be configured.
The SDK MUST provide a programmatic interface for all configuration. This interface SHOULD be written in the language of the SDK itself. All other configuration mechanisms SHOULD be built on top of this interface.
An example of this programmatic interface is accepting a well-defined struct on an SDK builder class. From that, one could build a CLI that accepts a file (YAML, JSON, TOML, ...) and then transforms into that well-defined struct consumable by the programmatic interface ( see declarative configuration).
Environment variable configuration defines a set of language agnostic environment variables for common configuration goals.
See OpenTelemetry Environment Variable Specification.
Declarative configuration provides a mechanism for configuring OpenTelemetry which is more expressive and full-featured than the environment variable based scheme, and language agnostic in a way not possible with programmatic configuration. Notably, declarative configuration defines tooling allowing users to load OpenTelemetry components according to a file-based representation of a standardized configuration data model.
Declarative configuration consists of the following main components:
- Data model defines data structures which allow users to specify an intended configuration of OpenTelemetry SDK components and instrumentation. The data model includes a file-based representation.
- Instrumentation configuration API allows instrumentation libraries to consume configuration by reading relevant configuration options during initialization.
- Configuration SDK defines SDK capabilities around file configuration, including an In-Memory configuration model, support for referencing custom extension plugin interfaces in configuration files, and operations to parse configuration files and interpret the configuration data model.
Additional configuration mechanisms SHOULD be provided in whatever language/format/style is idiomatic for the language of the SDK. The SDK can include as many configuration mechanisms as appropriate.