feat: Add compatibility with env OTEL_SDK_DISABLED (#1773)

* feat: disable SDK with env OTEL_SDK_DISABLED is defined as true

* feat: add tests

* fix: revert test

* feat: fix rubocop

* Update sdk/lib/opentelemetry/sdk.rb

Co-authored-by: Kayla Reopelle <[email protected]>

* feat: add test

* fix: fix rubocop

---------

Co-authored-by: Kayla Reopelle <[email protected]>

Author: pedrofurtado

sdk/lib/opentelemetry/sdk.rb

@@ -61,6 +61,11 @@ module SDK
     #       c.use_all
     #     end
     def configure
+      if ENV['OTEL_SDK_DISABLED'] == 'true'
+        OpenTelemetry.logger.warn 'Environment variable OTEL_SDK_DISABLED is defined as true. SDK is disabled.'
+        return
+      end
+
       configurator = Configurator.new
       yield configurator if block_given?
       configurator.configure

sdk/test/opentelemetry/sdk_test.rb

@@ -27,4 +27,13 @@
       _(received_message).must_match(/unexpected configuration error due to unknown keyword: .*invalid_option/)
     end
   end
+
+  describe '#configure (sdk disabled)' do
+    it 'ignore configuration when sdk is disabled by env' do
+      config = OpenTelemetry::TestHelpers.with_env('OTEL_SDK_DISABLED' => 'true') do
+        OpenTelemetry::SDK.configure
+      end
+      _(config).must_equal nil
+    end
+  end
 end