Logs API

Status: Stable, except where otherwise specified

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 API consist of these main components:

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

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: Specifies the name of 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.

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

Logger

The Logger is responsible for emitting LogRecords. There are two types of logging operations:

  • Log Bridge operations to be used when receiving data from other logging libraries.
  • Log Instrumentation operations to be used when writing instrumentation for OpenTelemetry.

The Logger contains methods for both types of operations. The Logger MUST provide a function to:

The Logger SHOULD provide functions to:

Log Bridge operations

Log Bridge operations are not intended to be used for writing instrumentation, and SHOULD include documentation that discourages this use.

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:

  • Timestamp (optional)
  • Observed Timestamp (optional). If unspecified the implementation SHOULD set it equal to the current time.
  • The Context associated with the LogRecord. When implicit Context is supported, then this parameter SHOULD be optional and if unspecified then MUST use current Context. When only explicit Context is supported, this parameter SHOULD be required.
  • Severity Number (optional)
  • Severity Text (optional)
  • Body (optional)
  • Attributes (optional)

Enabled

Status: Development

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

The API SHOULD accept the following parameters:

  • The Context to be associated with the LogRecord. When implicit Context is supported, then this parameter SHOULD be optional and if unspecified then MUST use current Context. When only explicit Context is supported, accepting this parameter is REQUIRED.
  • Severity Number (optional)

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.

Log Instrumentation operations

Emit an Event

Status: Development

The effect of calling this API is to emit a LogRecord to the processing pipeline formatted as an event.

Parameters:

  • The Name of the Event.
  • Timestamp (optional)
  • Observed Timestamp (optional). If unspecified the implementation SHOULD set it equal to the current time.
  • The Context associated with the Event. When implicit Context is supported, then this parameter SHOULD be optional and if unspecified then MUST use current Context. When only explicit Context is supported, this parameter SHOULD be required.
  • Severity Number (optional)
  • Severity Text (optional)
  • Body (optional)
  • Attributes (optional) Event Attributes conform to the standard definition of an attribute.

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 APIs provide specific guarantees and safeties.

LoggerProvider - all methods are safe to be called concurrently.

Logger - all methods are safe to be called concurrently.

References