fix: allow env var override of service.name (#592)

* fix: allow env var override of service.name

* fix: leaky state

Author: fbogsany

sdk/lib/opentelemetry/sdk/resources/resource.rb

@@ -31,7 +31,7 @@ def create(attributes = {})
           end
 
           def default
-            @default ||= telemetry_sdk.merge(process).merge(create(Constants::SERVICE_RESOURCE[:name] => 'unknown_service'))
+            @default ||= create(Constants::SERVICE_RESOURCE[:name] => 'unknown_service').merge(process).merge(telemetry_sdk)
           end
 
           def telemetry_sdk

sdk/test/opentelemetry/sdk/resources/resource_test.rb

@@ -42,6 +42,14 @@
   end
 
   describe '.default' do
+    before do
+      Resource.instance_variable_set(:@default, nil)
+    end
+
+    after do
+      Resource.instance_variable_set(:@default, nil)
+    end
+
     it 'contains telemetry sdk attributes' do
       resource_attributes = Resource.default.attribute_enumerator.to_h
       _(resource_attributes).must_include('telemetry.sdk.name')
@@ -63,6 +71,14 @@
       _(resource_attributes).must_include('service.name')
       _(resource_attributes['service.name']).must_equal('unknown_service')
     end
+
+    it 'allows overriding the default service.name with the environment variable' do
+      with_env('OTEL_RESOURCE_ATTRIBUTES' => 'service.name=svc') do
+        resource_attributes = Resource.default.attribute_enumerator.to_h
+        _(resource_attributes).must_include('service.name')
+        _(resource_attributes['service.name']).must_equal('svc')
+      end
+    end
   end
 
   describe '.telemetry_sdk' do