Experimental support for Open telemetry logs

lib/semantic_logger/appender.rb

@@ -17,6 +17,7 @@ module Appender
     autoload :MongoDB,             "semantic_logger/appender/mongodb"
     autoload :NewRelic,            "semantic_logger/appender/new_relic"
     autoload :NewRelicLogs,        "semantic_logger/appender/new_relic_logs"
+    autoload :OpenTelemetry,       "semantic_logger/appender/open_telemetry"
     autoload :Rabbitmq,            "semantic_logger/appender/rabbitmq"
     autoload :Splunk,              "semantic_logger/appender/splunk"
     autoload :SplunkHttp,          "semantic_logger/appender/splunk_http"

lib/semantic_logger/appender/open_telemetry.rb

@@ -0,0 +1,84 @@
+begin
+  require "opentelemetry/logs"
+rescue LoadError
+  raise LoadError, 'Gem opentelemetry-logs-sdk is required for logging to Open Telemetry. Please add the gem "opentelemetry-logs-sdk" to your Gemfile.'
+end
+
+# Open Telemetry Appender
+#
+#   Writes log messages, and metrics to Open Telemetry.
+#
+module SemanticLogger
+  module Appender
+    class OpenTelemetry < SemanticLogger::Subscriber
+      attr_reader :name, :version, :logger
+
+      CAPTURE_CONTEXT = ->(log) { log.set_context(:open_telemetry, ::OpenTelemetry::Context.current) }
+
+      # Create a Open Telemetry Logger appender instance.
+      #
+      # Metric only log events are sent to the Open Telemetry Metrics API instead of the Logs API.
+      #   I.e. A metric without a message or an exception.
+      #   To disable this default behavior set `metrics: false`
+      #
+      # Example
+      #    SemanticLogger.add_appender(appender: :open_telemetry)
+      def initialize(name: "SemanticLogger",
+                     version: SemanticLogger::VERSION,
+                     formatter: SemanticLogger::Formatters::OpenTelemetry.new,
+                     metrics: true,
+                     **args,
+                     &block)
+        @name    = name
+        @version = version
+        @logger  = ::OpenTelemetry.logger_provider.logger(name: @name, version: @version)
+
+        # Capture the current Open Telemetry context when a log entry is captured.
+        # Prevents duplicate subscribers as long as it is from a constant.
+        SemanticLogger.on_log(CAPTURE_CONTEXT)
+
+        super(formatter: formatter, metrics: metrics, **args, &block)
+      end
+
+      def log(log)
+        # return log_metric(log) if metrics && log.metric_only?
+
+        body        = formatter.call(log, self)
+        level       = body.delete(:level)
+        level_index = body.delete(:level_index)
+        time        = body.delete(:time)
+        payload     = body.delete(:payload)
+
+        @logger.on_emit(
+          severity_text:   level,
+          severity_number: level_index,
+          timestamp:       time,
+          body:            body.transform_keys!(&:to_s),
+          attributes:      payload,
+          context:         log.context[:open_telemetry] || ::OpenTelemetry::Context.current
+        )
+        true
+      end
+
+      # Flush all pending logs.
+      def flush
+        @logger.logger_provider.force_flush
+      end
+
+      # Flush pending logs and close the appender
+      def close
+        @logger.logger_provider.shutdown
+      end
+
+      private
+
+      # For logging metrics only log events.
+      # def log_metric(log)
+      #   puts "**** TODO: Metric Only Event ****"
+      #   ap formatter.call(log, self)
+      #   ap log.payload
+      #   true
+      # end
+    end
+  end
+end

lib/semantic_logger/formatters.rb

@@ -1,17 +1,18 @@
 module SemanticLogger
   module Formatters
-    autoload :Base,         "semantic_logger/formatters/base"
-    autoload :Color,        "semantic_logger/formatters/color"
-    autoload :Default,      "semantic_logger/formatters/default"
-    autoload :Json,         "semantic_logger/formatters/json"
-    autoload :Raw,          "semantic_logger/formatters/raw"
-    autoload :OneLine,      "semantic_logger/formatters/one_line"
-    autoload :Signalfx,     "semantic_logger/formatters/signalfx"
-    autoload :Syslog,       "semantic_logger/formatters/syslog"
-    autoload :Fluentd,      "semantic_logger/formatters/fluentd"
-    autoload :Logfmt,       "semantic_logger/formatters/logfmt"
-    autoload :SyslogCee,    "semantic_logger/formatters/syslog_cee"
-    autoload :NewRelicLogs, "semantic_logger/formatters/new_relic_logs"
+    autoload :Base,          "semantic_logger/formatters/base"
+    autoload :Color,         "semantic_logger/formatters/color"
+    autoload :Default,       "semantic_logger/formatters/default"
+    autoload :Json,          "semantic_logger/formatters/json"
+    autoload :Raw,           "semantic_logger/formatters/raw"
+    autoload :OneLine,       "semantic_logger/formatters/one_line"
+    autoload :OpenTelemetry, "semantic_logger/formatters/open_telemetry"
+    autoload :Signalfx,      "semantic_logger/formatters/signalfx"
+    autoload :Syslog,        "semantic_logger/formatters/syslog"
+    autoload :Fluentd,       "semantic_logger/formatters/fluentd"
+    autoload :Logfmt,        "semantic_logger/formatters/logfmt"
+    autoload :SyslogCee,     "semantic_logger/formatters/syslog_cee"
+    autoload :NewRelicLogs,  "semantic_logger/formatters/new_relic_logs"
 
     # Return formatter that responds to call.
     #

lib/semantic_logger/formatters/open_telemetry.rb

@@ -0,0 +1,40 @@
+require "json"
+module SemanticLogger
+  module Formatters
+    class OpenTelemetry < Raw
+      # Log level
+      def level
+        hash[:level]       = log.level.to_s
+        hash[:level_index] = severity_number(log.level_index)
+      end
+
+      # Payload is submitted directly as attributes
+      def payload
+        return unless log.payload.respond_to?(:empty?) && !log.payload.empty?
+
+        hash[:payload] = log.payload.transform_keys!(&:to_s)
+      end
+
+      private
+
+      def severity_number(severity)
+        case severity
+        when :trace
+          ::OpenTelemetry::Logs::SeverityNumber::SEVERITY_NUMBER_TRACE
+        when :debug
+          ::OpenTelemetry::Logs::SeverityNumber::SEVERITY_NUMBER_DEBUG
+        when :info
+          ::OpenTelemetry::Logs::SeverityNumber::SEVERITY_NUMBER_INFO
+        when :warn
+          ::OpenTelemetry::Logs::SeverityNumber::SEVERITY_NUMBER_WARN
+        when :error
+          ::OpenTelemetry::Logs::SeverityNumber::SEVERITY_NUMBER_ERROR
+        when :fatal
+          ::OpenTelemetry::Logs::SeverityNumber::SEVERITY_NUMBER_FATAL
+        else
+          ::OpenTelemetry::Logs::SeverityNumber::SEVERITY_NUMBER_UNSPECIFIED
+        end
+      end
+    end
+  end
+end