opentelemetry logging integration

[maierlars]

Right now abseil is very opinionated how logged messages are supposed to leave the application. If you want to integrate well with opentelemetry-cpp one can do something like this:

class open_telemetry_log_sink : public absl::LogSink
{
 public:
	explicit open_telemetry_log_sink(std::shared_ptr<opentelemetry::logs::Logger> logger)
		: _logger(std::move(logger))
	{
	}

	static otel::logs::Severity convert_absl_severity(absl::LogSeverity s)
	{
		switch (s)
		{
		case absl::LogSeverity::kInfo:
			return otel::logs::Severity::kInfo;
		case absl::LogSeverity::kWarning:
			return otel::logs::Severity::kWarn;
		case absl::LogSeverity::kError:
			return otel::logs::Severity::kError;
		case absl::LogSeverity::kFatal:
			return otel::logs::Severity::kFatal;
		}
	}

	void Send(const absl::LogEntry& entry) override
	{
		// TODO add further information, like filename, line, timestamp etc
		_logger->Log(convert_absl_severity(entry.log_severity()), entry.text_message());
	}

	std::shared_ptr<opentelemetry::v1::logs::Logger> _logger;
};

// [...]
	open_telemetry_log_sink log_sink{ logger };
	absl::AddLogSink(&log_sink);

which will expose the log messages to open-telemetry. However, abseil still logs to stdout or stderr, in a format that is not customizable!

I would like to discuss how such an integration could look like, in particular, because gRPC has already an open-telemetry plugin to provide metrics and uses abseil for logging.

Maybe there are already plans? Or there is already a well supported integration and my google skills are just lacking.