Enable deprecation log indexing by default

server/src/main/java/org/elasticsearch/common/logging/RateLimitingFilter.java

@@ -29,7 +29,9 @@
 import static org.elasticsearch.common.logging.DeprecatedMessage.X_OPAQUE_ID_FIELD_NAME;
 
 @Plugin(name = "RateLimitingFilter", category = Node.CATEGORY, elementType = Filter.ELEMENT_TYPE)
-public class RateLimitingFilter extends AbstractFilter {
+public class RateLimitingFilter extends AbstractFilter  {
+
+    private volatile boolean useXOpaqueId = true;
 
     private final Set<String> lruKeyCache = Collections.newSetFromMap(Collections.synchronizedMap(new LinkedHashMap<>() {
         @Override
@@ -57,16 +59,23 @@ public Result filter(Message message) {
         if (message instanceof ESLogMessage) {
             final ESLogMessage esLogMessage = (ESLogMessage) message;
 
-            String xOpaqueId = esLogMessage.get(X_OPAQUE_ID_FIELD_NAME);
-            final String key = esLogMessage.get(KEY_FIELD_NAME);
-
-            return lruKeyCache.add(xOpaqueId + key) ? Result.ACCEPT : Result.DENY;
+            final String key = getKey(esLogMessage);
+            return lruKeyCache.add(key) ? Result.ACCEPT : Result.DENY;
 
         } else {
             return Result.NEUTRAL;
         }
     }
 
+    private String getKey(ESLogMessage esLogMessage) {
+        final String key = esLogMessage.get(KEY_FIELD_NAME);
+        if (useXOpaqueId) {
+            String xOpaqueId = esLogMessage.get(X_OPAQUE_ID_FIELD_NAME);
+            return xOpaqueId + key;
+        }
+        return key;
+    }
+
     @Override
     public Result filter(LogEvent event) {
         return filter(event.getMessage());
@@ -84,4 +93,8 @@ public static RateLimitingFilter createFilter(
     ) {
         return new RateLimitingFilter(match, mismatch);
     }
+
+    public void setUseXOpaqueId(boolean useXOpaqueId) {
+        this.useXOpaqueId = useXOpaqueId;
+    }
 }

server/src/test/java/org/elasticsearch/common/logging/RateLimitingFilterTests.java

@@ -147,4 +147,26 @@ public void testFilterCanBeReset() {
         // Third time, it is allowed again
         assertThat(filter.filter(message), equalTo(Result.ACCEPT));
     }
+
+    public void testMessagesXOpaqueIsIgnoredWhenDisabled() {
+        RateLimitingFilter filter = new RateLimitingFilter();
+        filter.setUseXOpaqueId(false);
+        filter.start();
+
+        // Should NOT be rate-limited because it's not in the cache
+        Message message = DeprecatedMessage.of(DeprecationCategory.OTHER, "key 0", "opaque-id 0", "msg 0");
+        assertThat(filter.filter(message), equalTo(Result.ACCEPT));
+
+        // Should  be rate-limited because it was just added to the cache
+        message = DeprecatedMessage.of(DeprecationCategory.OTHER, "key 0", "opaque-id 0", "msg 0");
+        assertThat(filter.filter(message), equalTo(Result.DENY));
+
+        // Should be rate-limited because X-Opaque-Id is not used
+        message = DeprecatedMessage.of(DeprecationCategory.OTHER, "key 0", "opaque-id 1", "msg 0");
+        assertThat(filter.filter(message), equalTo(Result.DENY));
+
+        // Should NOT be rate-limited because "key 1" it not in the cache
+        message = DeprecatedMessage.of(DeprecationCategory.OTHER, "key 1", "opaque-id 1", "msg 0");
+        assertThat(filter.filter(message), equalTo(Result.ACCEPT));
+    }
 }

x-pack/plugin/deprecation/src/main/java/org/elasticsearch/xpack/deprecation/logging/DeprecationIndexingComponent.java

@@ -49,11 +49,16 @@ public class DeprecationIndexingComponent extends AbstractLifecycleComponent imp
 
     public static final Setting<Boolean> WRITE_DEPRECATION_LOGS_TO_INDEX = Setting.boolSetting(
         "cluster.deprecation_indexing.enabled",
-        false,
+        true,
+        Setting.Property.NodeScope,
+        Setting.Property.Dynamic
+    );
+    public static final Setting<Boolean> USE_X_OPAQUE_ID_IN_FILTERING = Setting.boolSetting(
+        "cluster.deprecation_indexing.x_opaque_id_used.enabled",
+        true,
         Setting.Property.NodeScope,
         Setting.Property.Dynamic
     );
-
     private final DeprecationIndexingAppender appender;
     private final BulkProcessor processor;
     private final RateLimitingFilter filter;
@@ -110,6 +115,8 @@ public void clusterChanged(ClusterChangedEvent event) {
             }
             appender.setEnabled(newEnabled);
         }
+        final boolean useXOpaqueId = USE_X_OPAQUE_ID_IN_FILTERING.get(state.getMetadata().settings());
+        this.filter.setUseXOpaqueId(useXOpaqueId);
     }
 
     /**