Crate opentelemetry_appender_log

Bridge log into OpenTelemetry.

This library implements a log appender for the log crate using the Logs Bridge API.

Supported Rust Versions

Getting Started

The bridge requires configuration on both the log and OpenTelemetry sides.

For OpenTelemetry, configure a LoggerProvider with the desired exporter:

let exporter = opentelemetry_stdout::LogExporter::default();

let logger_provider = SdkLoggerProvider::builder()
    .with_log_processor(BatchLogProcessor::builder(exporter).build())
    .build();

For log, set the global logger to an OpenTelemetryLogBridge instance using the LoggerProvider:

let otel_log_appender = OpenTelemetryLogBridge::new(&logger_provider);

log::set_boxed_logger(Box::new(otel_log_appender)).unwrap();

Mapping Log Records

This section outlines how log records produced by log are mapped into OpenTelemetry log records. Each subsection deals with a different property on opentelemetry::logs::LogRecord.

Body

The body is the stringified message (log::Record::args).

Severity

The severity number and text are mapped from the log::Level (log::Record::level):

log::Level	Severity Text	Severity Number
Error	Error	17
Warn	Warn	13
Info	Info	9
Debug	Debug	5
Trace	Trace	1

Attributes

Any key-values (log::Record::key_values) are converted into attributes:

Type	Result	Notes
i8-i128	AnyValue::Int	If the value is too big then it will be stringified using std::fmt::Display
u8-u128	AnyValue::Int	If the value is too big then it will be stringified using std::fmt::Display
f32-f64	AnyValue::Double
bool	AnyValue::Boolean
str	AnyValue::String
Bytes	AnyValue::Bytes	Requires the with-serde feature, otherwise it will be stringified using std::fmt::Debug
()	-	Unit values are discared
Some	Any	Some variants use their inner value
None	-	None variants are discared
Unit struct	AnyValue::String	Uses the name of the struct
Unit variant	AnyValue::String	Uses the name of the variant
Newtype struct	Any	Uses the inner value of the newtype
Newtype variant	AnyValue::Map	An internally-tagged map. Requires the with-serde feature, otherwise it will be stringified using std::fmt::Debug
Sequence	AnyValue::ListAny	Requires the with-serde feature, otherwise it will be stringified using std::fmt::Debug
Tuple	AnyValue::ListAny	Requires the with-serde feature, otherwise it will be stringified using std::fmt::Debug
Tuple struct	AnyValue::ListAny	Requires the with-serde feature, otherwise it will be stringified using std::fmt::Debug
Tuple variant	AnyValue::Map	An internally-tagged map. Requires the with-serde feature, otherwise it will be stringified using std::fmt::Debug
Map	AnyValue::Map	Requires the with-serde feature, otherwise it will be stringified using std::fmt::Debug
Struct	AnyValue::Map	Requires the with-serde feature, otherwise it will be stringified using std::fmt::Debug
Struct variant	AnyValue::Map	An internally-tagged map. Requires the with-serde feature, otherwise it will be stringified using std::fmt::Debug

Feature Flags

This library provides the following Cargo features:

• spec_unstable_logs_enabled: Allow users to control the log level.
• with-serde: Support complex values as attributes without stringifying them.

Supported Rust Versions

OpenTelemetry is built against the latest stable release. The minimum supported version is 1.70. The current OpenTelemetry version is not guaranteed to build on Rust versions earlier than the minimum supported version.

The current stable Rust compiler and the three most recent minor versions before it will always be supported. For example, if the current stable compiler version is 1.49, the minimum supported version will not be increased past 1.46, three minor versions prior. Increasing the minimum supported compiler version is not considered a semver breaking change as long as doing so complies with this policy.

Structs

OpenTelemetryLogBridge