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Logs Bridge API

Status: Stable, except where otherwise specified

Table of Contents

Note: this document defines a log backend API. The API is not intended to be called by application developers directly. It is provided for logging library authors to build log appenders, which use this API to bridge between existing logging libraries and the OpenTelemetry log data model.

The Logs Bridge API consist of these main components:

graph TD
    A[LoggerProvider] -->|Get| B(Logger)
    B -->|Emit| C(LogRecord)
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LoggerProvider

Loggers can be accessed with a LoggerProvider.

Normally, the LoggerProvider is expected to be accessed from a central place. Thus, the API SHOULD provide a way to set/register and access a global default LoggerProvider.

LoggerProvider operations

The LoggerProvider MUST provide the following functions:

  • Get a Logger

Get a Logger

This API MUST accept the following instrumentation scope parameters:

  • name: This name uniquely identifies the instrumentation scope, such as the instrumentation library (e.g. io.opentelemetry.contrib.mongodb), package, module or class name. If an application or library has built-in OpenTelemetry instrumentation, both Instrumented library and Instrumentation library may refer to the same library. In that scenario, the name denotes a module name or component name within that library or application. For log sources which define a logger name (e.g. Java Logger Name) the Logger Name should be recorded as the instrumentation scope name.

  • version (optional): Specifies the version of the instrumentation scope if the scope has a version (e.g. a library version). Example value: 1.0.0.

  • schema_url (optional): Specifies the Schema URL that should be recorded in the emitted telemetry.

  • attributes (optional): Specifies the instrumentation scope attributes to associate with emitted telemetry. This API MUST be structured to accept a variable number of attributes, including none.

Loggers are identified by name, version, and schema_url fields. When more than one Logger of the same name, version, and schema_url is created, it is unspecified whether or under which conditions the same or different Logger instances are returned. It is a user error to create Loggers with different attributes but the same identity.

The term identical applied to Loggers describes instances where all identifying fields are equal. The term distinct applied to Loggers describes instances where at least one identifying field has a different value.

The effect of associating a Schema URL with a Logger MUST be that the telemetry emitted using the Logger will be associated with the Schema URL, provided that the emitted data format is capable of representing such association.

Logger

The Logger is responsible for emitting LogRecords.

Logger operations

The Logger MUST provide functions to:

The Logger SHOULD provide functions to:

Emit a LogRecord

The effect of calling this API is to emit a LogRecord to the processing pipeline.

The API MUST accept the following parameters:

All parameters are optional.

Enabled

Status: Development

To help users avoid performing computationally expensive operations when generating a LogRecord, a Logger SHOULD provide this Enabled API.

There are currently no required parameters for this API. Parameters can be added in the future, therefore, the API MUST be structured in a way for parameters to be added.

This API MUST return a language idiomatic boolean type. A returned value of true means the Logger is enabled for the provided arguments, and a returned value of false means the Logger is disabled for the provided arguments.

The returned value is not always static, it can change over time. The API SHOULD be documented that instrumentation authors needs to call this API each time they emit a LogRecord to ensure they have the most up-to-date response.

Optional and required parameters

The operations defined include various parameters, some of which are marked optional. Parameters not marked optional are required.

For each optional parameter, the API MUST be structured to accept it, but MUST NOT obligate a user to provide it.

For each required parameter, the API MUST be structured to obligate a user to provide it.

Concurrency requirements

For languages which support concurrent execution the Logs Bridge APIs provide specific guarantees and safeties.

LoggerProvider - all methods are safe to be called concurrently.

Logger - all methods are safe to be called concurrently.

Artifact Naming

The Logs Bridge API is not intended to be called by application developers directly, and SHOULD include documentation that discourages direct use. However, in the event OpenTelemetry were to add a user facing API, the Logs Bridge API would be a natural starting point. Therefore, Log Bridge API artifact, package, and class names MUST NOT include the terms "bridge", "appender", or any other qualifier that would prevent evolution into a user facing API.

References