more clean ups, address all open comments

Author: mabdinur

docs/OpenTelemetry.md

@@ -5,8 +5,8 @@
 | Type          | Documentation                                        | datadog version | Gem version support |
 | ------------- | ---------------------------------------------------- | --------------- | ------------------- |
 | Tracing       | https://github.com/open-telemetry/opentelemetry-ruby | 1.9.0+          | >= 1.1.0            |
-| Metrics SDK   | https://rubygems.org/gems/opentelemetry-metrics-sdk  | 2.25.0+         |  >= 0.8             |
-| OTLP Metrics Exporter | https://rubygems.org/gems/opentelemetry-exporter-otlp-metrics  | 2.25.0+         |  >= 0.4            |
+| Metrics SDK   | https://rubygems.org/gems/opentelemetry-metrics-sdk  | 2.23.0+         |  >= 0.8             |
+| OTLP Metrics Exporter | https://rubygems.org/gems/opentelemetry-exporter-otlp-metrics  | 2.23.0+         |  >= 0.4            |
 
 ## Configuring OpenTelemetry Tracing
 
@@ -48,7 +48,7 @@
 
 ## Configuring OpenTelemetry Metrics
 
-1. Add required gems to your Gemfile:
+1. Add the required gems to your Gemfile:
 
     ```ruby
     gem 'datadog'
@@ -64,23 +64,21 @@
     # Set environment variable before initializing metrics support
     ENV['DD_METRICS_OTEL_ENABLED'] = 'true'
     require 'opentelemetry/sdk'
-    require 'opentelemetry-metrics-sdk'
-    require 'opentelemetry/exporter/otlp_metrics'
     require 'datadog/opentelemetry'
 
-    # IMPORTANT: Call Datadog.configure before OpenTelemetry::SDK.configure
-    # and keep both in the same file to ensure proper initialization order.
     Datadog.configure do |c|
       # Configure Datadog settings here
     end
 
-    # Initialize OpenTelemetry SDK (required for metrics)
+    # Call after Datadog.configure to initialize metrics.
+    # Can be called multiple times to pick up configuration changes.
+    # Requires: opentelemetry/exporter/otlp_metrics and opentelemetry/exporter/otlp_metrics
     OpenTelemetry::SDK.configure
     ```
 
 1. Use the [OpenTelemetry Metrics API](https://opentelemetry.io/docs/languages/ruby/instrumentation/#metrics) to create and record metrics.
 
-**Note:** Call `Datadog.configure` before `OpenTelemetry::SDK.configure` and keep both in the same file. Configuration changes require calling `OpenTelemetry::SDK.configure` again to take effect.
+**Note:** Call `OpenTelemetry::SDK.configure` after `Datadog.configure` and call it again whenever Datadog configuration changes to update the meter provider.
 
 **Configuration Options:**
 

lib/datadog/core/configuration/settings.rb

@@ -1032,7 +1032,6 @@ def initialize(*_)
         #       Keep this extension here for now to keep things working.
         extend Datadog::Tracing::Configuration::Settings
 
-        # OpenTelemetry Metrics settings
         extend Datadog::OpenTelemetry::Configuration::Settings
       end
       # standard:enable Metrics/BlockLength

lib/datadog/core/runtime/metrics.rb

@@ -97,7 +97,7 @@ def gc_metrics
         def try_flush
           yield
         rescue => e
-          Datadog.logger.warn("Error while sending runtime metric. Cause: #{e.class.name}  #{e.class}: #{e}")
+          Datadog.logger.warn("Error while sending runtime metric. Cause: #{e.class.name} #{e.message}")
         end
 
         def default_metric_options

lib/datadog/opentelemetry/configuration/settings.rb

@@ -34,7 +34,7 @@ def self.normalize_protocol(env_var_name)
         end
 
         def self.headers_parser(env_var_name)
-          proc do |value|
+          lambda do |value|
             return {} if value.nil? || value.empty?
 
             headers = {}

lib/datadog/opentelemetry/metrics.rb

@@ -4,23 +4,25 @@
 
 module Datadog
   module OpenTelemetry
-    module Metrics
+    class Metrics
       EXPORTER_NONE = 'none'
 
       def self.initialize!(components)
+        new(components).configure_metrics_sdk
+        true
+      rescue => exc
+        components.logger.error("Failed to initialize OpenTelemetry metrics: #{exc.class}: #{exc}: #{exc.backtrace.join("\n")}")
+        false
+      end
+
+      def initialize(components)
         @logger = components.logger
         @settings = components.settings
         @agent_host = components.agent_settings.hostname
         @agent_ssl = components.agent_settings.ssl
-
-        configure_metrics_sdk
-        true
-      rescue => exc
-        @logger.error("Failed to initialize OpenTelemetry metrics: #{exc.class}: #{exc}: #{exc.backtrace.join("\n")}")
-        false
       end
 
-      def self.configure_metrics_sdk
+      def configure_metrics_sdk
         provider = ::OpenTelemetry.meter_provider
         provider.shutdown if provider.is_a?(::OpenTelemetry::SDK::Metrics::MeterProvider)
 
@@ -36,7 +38,7 @@ def self.configure_metrics_sdk
         ::OpenTelemetry.meter_provider = provider
       end
 
-      def self.create_resource
+      def create_resource
         resource_attributes = {}
         resource_attributes['host.name'] = Datadog::Core::Environment::Socket.hostname if @settings.tracing.report_hostname
 
@@ -50,32 +52,32 @@ def self.create_resource
           resource_attributes[otel_key] = value
         end
 
-        resource_attributes['service.name'] = @settings.service_without_fallback || resource_attributes['service.name'] || ''
+        resource_attributes['service.name'] = @settings.service_without_fallback || resource_attributes['service.name'] || Datadog::Core::Environment::Ext::FALLBACK_SERVICE_NAME
         resource_attributes['deployment.environment'] = @settings.env if @settings.env
         resource_attributes['service.version'] = @settings.version if @settings.version
 
         ::OpenTelemetry::SDK::Resources::Resource.create(resource_attributes)
       end
 
-      def self.configure_metric_reader(provider)
+      def configure_metric_reader(provider)
         exporter_name = @settings.opentelemetry.metrics.exporter
-        return if exporter_name == Datadog::OpenTelemetry::Metrics::EXPORTER_NONE
+        return if exporter_name == EXPORTER_NONE
 
         configure_otlp_exporter(provider)
       rescue => e
         @logger.warn("Failed to configure OTLP metrics exporter:  #{e.class}: #{e}")
       end
 
-      def self.resolve_metrics_endpoint
+      def resolve_metrics_endpoint
         metrics_config = @settings.opentelemetry.metrics
         exporter_config = @settings.opentelemetry.exporter
 
-        return metrics_config.endpoint.to_s if metrics_config.endpoint
-        return exporter_config.endpoint.to_s if exporter_config.endpoint
+        return metrics_config.endpoint if metrics_config.endpoint
+        return exporter_config.endpoint if exporter_config.endpoint
         "#{@agent_ssl ? "https" : "http"}://#{@agent_host}:4318/v1/metrics"
       end
 
-      def self.configure_otlp_exporter(provider)
+      def configure_otlp_exporter(provider)
         require 'opentelemetry/exporter/otlp_metrics'
         require_relative 'sdk/metrics_exporter'
 
@@ -102,7 +104,7 @@ def self.configure_otlp_exporter(provider)
         @logger.warn("Could not load OTLP metrics exporter:  #{e.class}: #{e}")
       end
 
-      private_class_method :configure_metrics_sdk, :create_resource, :configure_metric_reader, :resolve_metrics_endpoint, :configure_otlp_exporter
+      private :create_resource, :configure_metric_reader, :resolve_metrics_endpoint, :configure_otlp_exporter
     end
   end
 end

sig/datadog/opentelemetry/metrics.rbs

@@ -1,21 +1,23 @@
 module Datadog
   module OpenTelemetry
-    module Metrics
+    class Metrics
       EXPORTER_NONE: ::String
 
       def self.initialize!: (Core::Configuration::Components components) -> bool
 
-      private
+      def initialize: (Core::Configuration::Components components) -> void
+
+      def configure_metrics_sdk: () -> void
 
-      def self.configure_metrics_sdk: () -> void
+      private
 
-      def self.create_resource: () -> untyped
+      def create_resource: () -> untyped
 
-      def self.configure_metric_reader: (untyped provider) -> void
+      def configure_metric_reader: (untyped provider) -> void
 
-      def self.resolve_metrics_endpoint: () -> ::String
+      def resolve_metrics_endpoint: () -> ::String
 
-      def self.configure_otlp_exporter: (untyped provider) -> void
+      def configure_otlp_exporter: (untyped provider) -> void
     end
   end
 end