Fix hash log_tags warning

lib/datadog/tracing/contrib/rails/log_injection.rb

@@ -8,9 +8,12 @@ module LogInjection
           module_function
 
           # Use `app.config.log_tags` to inject propagation tags into the default Rails logger.
-          def configure_log_tags(app)
-            app.config.log_tags ||= [] # Can be nil, we initialized it if so
-            app.config.log_tags << proc { Tracing.log_correlation if Datadog.configuration.tracing.log_injection }
+          def configure_log_tags(app_cofig)
+            # Semantic Logger's named tags override Rails built-in config.log_tags with a hash value
+            return if Hash === app_cofig.log_tags
+
+            app_cofig.log_tags ||= [] # Can be nil, we initialized it if so
+            app_cofig.log_tags << proc { Tracing.log_correlation if Datadog.configuration.tracing.log_injection }
           rescue StandardError => e
             Datadog.logger.warn(
               "Unable to add Datadog Trace context to ActiveSupport::TaggedLogging: #{e.class.name} #{e.message}"

lib/datadog/tracing/contrib/rails/patcher.rb

@@ -41,7 +41,7 @@ def before_initialize(app)
               # Sometimes we don't want to activate middleware e.g. OpenTracing, etc.
               add_middleware(app) if Datadog.configuration.tracing[:rails][:middleware]
 
-              Rails::LogInjection.configure_log_tags(app)
+              Rails::LogInjection.configure_log_tags(app.config)
             end
           end
 

spec/datadog/tracing/contrib/rails/log_injection_spec.rb

@@ -0,0 +1,53 @@
+require 'datadog/tracing/contrib/rails/log_injection'
+
+RSpec.describe Datadog::Tracing::Contrib::Rails::LogInjection do
+  describe '.configure_log_tags' do
+    context 'when given `nil` as `log_tags` configuration ' do
+      it 'sets an array and adds a proc to the config' do
+        expect(Datadog.logger).not_to receive(:warn)
+
+        config = OpenStruct.new(log_tags: nil)
+
+        expect do
+          described_class.configure_log_tags(config)
+        end.to change { config.log_tags }.from(nil).to(be_an(Array).and(have(1).item))
+      end
+    end
+
+    context 'when given an array as `log_tags` configuration ' do
+      it 'adds a proc to the config' do
+        expect(Datadog.logger).not_to receive(:warn)
+
+        config = OpenStruct.new(log_tags: [])
+
+        expect do
+          described_class.configure_log_tags(config)
+        end.to change { config.log_tags }.from([]).to(be_an(Array).and(have(1).item))
+      end
+    end
+
+    context 'when given a hash as `log_tags` configuration ' do
+      it 'deos not change the configuration' do
+        expect(Datadog.logger).not_to receive(:warn)
+
+        config = OpenStruct.new(log_tags: {})
+
+        expect do
+          described_class.configure_log_tags(config)
+        end.not_to(change { config.log_tags })
+      end
+    end
+
+    context 'when given a string as `log_tags` configuration ' do
+      it 'deos not change the configuration and warn about the error' do
+        expect(Datadog.logger).to receive(:warn)
+
+        config = OpenStruct.new(log_tags: 'misconfigured with a string')
+
+        expect do
+          described_class.configure_log_tags(config)
+        end.not_to(change { config.log_tags })
+      end
+    end
+  end
+end