Move default decorators to code

Author: Andrew Kent

dd-java-agent/src/main/resources/dd-trace-decorators-default.yaml

@@ -0,0 +1,16 @@
+# Decorators are used to add extra information to span.
+# To modify, copy the file to dd-trace-decorators.yaml and make desired changes.
+# Could be DBServiceDecorator or HTTPServiceDecorator, etc.
+decorators:
+  - type: HTTPComponent
+    matchingTag: component
+    matchingValue: okhttp
+  - type: HTTPComponent
+    matchingTag: component
+    matchingValue: java-aws-sdk
+  - type: ErrorFlag
+  - type: DBTypeDecorator
+  - type: DBStatementAsResourceName
+  - type: OperationDecorator
+  - type: Status404Decorator
+  - type: URLAsResourceName

dd-trace-ot/src/main/java/datadog/opentracing/decorators/DDDecoratorsFactory.java

@@ -68,12 +68,38 @@ public static List<AbstractDecorator> create(
   }
 
   public static List<AbstractDecorator> createFromResources() {
-    List<AbstractDecorator> result = new ArrayList<>();
+    final List<AbstractDecorator> result;
     final DecoratorsConfig config =
         ConfigUtils.loadConfigFromResource(CONFIG_PATH, DecoratorsConfig.class);
-    if (config != null) {
+    if (config == null) {
+      result = createBuiltinDecorators();
+    } else {
       result = DDDecoratorsFactory.create(config.getDecorators());
     }
     return result;
   }
+
+  private static List<AbstractDecorator> createBuiltinDecorators() {
+    List<AbstractDecorator> builtin = new ArrayList<AbstractDecorator>(8);
+    {
+      final HTTPComponent httpDecorator1 = new HTTPComponent();
+      httpDecorator1.setMatchingTag("component");
+      httpDecorator1.setMatchingValue("okhttp");
+      builtin.add(httpDecorator1);
+    }
+    {
+      final HTTPComponent httpDecorator2 = new HTTPComponent();
+      httpDecorator2.setMatchingTag("component");
+      httpDecorator2.setMatchingValue("java-aws-sdk");
+      builtin.add(httpDecorator2);
+    }
+    builtin.add(new ErrorFlag());
+    builtin.add(new DBTypeDecorator());
+    builtin.add(new DBStatementAsResourceName());
+    builtin.add(new OperationDecorator());
+    builtin.add(new Status404Decorator());
+    builtin.add(new URLAsResourceName());
+
+    return builtin;
+  }
 }