NH-85973: preload libraries from given lambda function

Author: xuan-cao-swi

lambda/otel/layer/Gemfile

@@ -4,8 +4,8 @@ source 'https://rubygems.org'
 
 source 'https://rubygems.pkg.github.com/solarwinds' do
   gem 'opentelemetry-exporter-otlp', '0.26.1'
-  gem 'opentelemetry-metrics-api', '0.0.1'
-  gem 'opentelemetry-metrics-sdk', '0.0.1'
 end
 
+gem 'opentelemetry-metrics-api', '0.1.0'
+gem 'opentelemetry-metrics-sdk', '0.1.0'
 gem 'solarwinds_apm', '6.0.2'

lambda/otel/layer/otel_wrapper.rb

@@ -3,11 +3,53 @@
 require 'opentelemetry-metrics-api'
 require 'opentelemetry-metrics-sdk'
 require 'opentelemetry-exporter-otlp'
-require 'opentelemetry/instrumentation/aws_lambda/handler'
 
-otel_lambda_handler = OpenTelemetry::Instrumentation::AwsLambda::Handler.new
+def preload_libraries
+  default_task_location = '/var/task'
+
+  handler_file = ENV.values_at('ORIG_HANDLER', '_HANDLER').compact.first&.split('.')&.first
+
+  unless handler_file && File.exist?("#{default_task_location}/#{handler_file}.rb")
+    OpenTelemetry.logger.warn { 'Could not find the original handler file to preload libraries.' }
+    return
+  end
+
+  libraries = File.read("#{default_task_location}/#{handler_file}.rb")
+                  .scan(/^\s*require\s+['"]([^'"]+)['"]/)
+                  .flatten
+
+  libraries.each do |lib|
+    require lib
+  rescue StandardError => e
+    OpenTelemetry.logger.warn { "Could not load library #{lib}: #{e.message}" }
+  end
+end
+
+preload_libraries
+
+require 'opentelemetry/instrumentation/aws_sdk/handler'
+require 'opentelemetry/instrumentation/aws_sdk/services'
+
+def loaded_constants
+  services = Aws.constants & OpenTelemetry::Instrumentation::AwsSdk::SERVICES.map(&:to_sym)
+
+  services.each_with_object([]) do |service, constants|
+    next if Aws.autoload?(service)
+
+    begin
+      constants << Aws.const_get(service, false).const_get(:Client, false)
+    rescue StandardError => e
+      OpenTelemetry.logger.warn { "Constant could not be loaded: #{e.message}" }
+    end
+  end
+end
+
+Seahorse::Client::Base.add_plugin(OpenTelemetry::Instrumentation::AwsSdk::Plugin) if defined?(Seahorse::Client::Base)
+loaded_constants.each { |klass| klass.add_plugin(OpenTelemetry::Instrumentation::AwsSdk::Plugin) }
+
 require 'solarwinds_apm'
 
-define_method(:otel_wrapper) do |event:, context:|
-  otel_lambda_handler.call_wrapped(event: event, context: context)
+def otel_wrapper(event:, context:)
+  otel_wrapper = OpenTelemetry::Instrumentation::AwsLambda::Handler.new
+  otel_wrapper.call_wrapped(event: event, context: context)
 end