Class: LaunchDarklyObservability::OtelLogBridge

Inherits:
Logger
  • Object
show all
Defined in:
lib/launchdarkly_observability/otel_log_bridge.rb

Overview

A Logger that forwards messages to the OpenTelemetry Logs pipeline.

When used as a broadcast target (Rails), pass only the logger_provider. When used standalone (Sinatra, plain Ruby), pass ‘io:` to also write to a local destination such as $stdout.

Examples:

Standalone usage (non-Rails)

logger = LaunchDarklyObservability.logger          # writes to $stdout + OTel

Manually attaching (the Railtie does this automatically)

bridge = LaunchDarklyObservability::OtelLogBridge.new(logger_provider)
Rails.logger.broadcast_to(bridge)   # Rails >= 7.1

Constant Summary collapse

SEVERITY_NUMBER =

OpenTelemetry severity numbers (base value per level). See: opentelemetry.io/docs/specs/otel/logs/data-model/#severity-fields

{
  ::Logger::DEBUG   => 5,
  ::Logger::INFO    => 9,
  ::Logger::WARN    => 13,
  ::Logger::ERROR   => 17,
  ::Logger::FATAL   => 21,
  ::Logger::UNKNOWN => 0
}.freeze
SEVERITY_TEXT = 
{
  ::Logger::DEBUG   => 'DEBUG',
  ::Logger::INFO    => 'INFO',
  ::Logger::WARN    => 'WARN',
  ::Logger::ERROR   => 'ERROR',
  ::Logger::FATAL   => 'FATAL',
  ::Logger::UNKNOWN => 'UNKNOWN'
}.freeze

Instance Method Summary collapse

Constructor Details

#initialize(logger_provider, io: nil) ⇒ OtelLogBridge

Returns a new instance of OtelLogBridge.

Parameters:

  • logger_provider (OpenTelemetry::SDK::Logs::LoggerProvider)
  • io (IO, nil) (defaults to: nil) —

    Optional IO for local output (e.g. $stdout). When nil the bridge only emits to OTel (suitable for broadcast).



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# File 'lib/launchdarkly_observability/otel_log_bridge.rb', line 41

def initialize(logger_provider, io: nil)
  super(File::NULL)
  @otel_logger = logger_provider.logger(
    name: 'launchdarkly-observability-ruby',
    version: LaunchDarklyObservability::VERSION
  )
  @local_logger = io ? ::Logger.new(io) : nil
end

Instance Method Details

#add(severity, message = nil, progname = nil) ⇒ Object

Core method that debug/info/warn/error/fatal all delegate to.



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# File 'lib/launchdarkly_observability/otel_log_bridge.rb', line 63

def add(severity, message = nil, progname = nil)
  severity ||= ::Logger::UNKNOWN
  return true if severity < level

  if message.nil?
    if block_given?
      message = yield
    else
      message = progname
      progname = nil
    end
  end

  return true if message.nil?

  attributes = {}
  if message.is_a?(Hash)
    attributes = message.each_with_object({}) { |(k, v), h| h[k.to_s] = v.to_s }
    body = message.inspect
  else
    body = message.to_s
  end

  begin
    @otel_logger.on_emit(
      body: body,
      severity_number: SEVERITY_NUMBER.fetch(severity, 0),
      severity_text: SEVERITY_TEXT.fetch(severity, 'UNKNOWN'),
      timestamp: Time.now,
      context: OpenTelemetry::Context.current,
      attributes: attributes
    )
  rescue StandardError
    # OTel export failures must not suppress local IO output.
  end

  begin
    @local_logger&.add(severity, message, progname)
  rescue StandardError
    # Local IO failures must not propagate.
  end

  true
end

#formatter=(formatter) ⇒ Object

Propagate formatter changes to the local logger.



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# File 'lib/launchdarkly_observability/otel_log_bridge.rb', line 57

def formatter=(formatter)
  super
  @local_logger&.formatter = formatter
end

#level=(severity) ⇒ Object

Propagate level changes to the local logger so filtering stays in sync.



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# File 'lib/launchdarkly_observability/otel_log_bridge.rb', line 51

def level=(severity)
  super
  @local_logger&.level = severity
end