Minor fixes to improve SystemIndexDescriptor (#113278)

Closes #112946

Author: ldematte

server/src/main/java/org/elasticsearch/action/admin/indices/create/AutoCreateAction.java

@@ -305,11 +305,14 @@ ClusterState execute(
                     final CreateIndexClusterStateUpdateRequest updateRequest;
 
                     if (isManagedSystemIndex) {
-                        final SystemIndexDescriptor descriptor = mainDescriptor.getDescriptorCompatibleWith(
-                            currentState.getMinSystemIndexMappingVersions().get(mainDescriptor.getPrimaryIndex())
-                        );
+                        final var requiredMinimumMappingVersion = currentState.getMinSystemIndexMappingVersions()
+                            .get(mainDescriptor.getPrimaryIndex());
+                        final SystemIndexDescriptor descriptor = mainDescriptor.getDescriptorCompatibleWith(requiredMinimumMappingVersion);
                         if (descriptor == null) {
-                            final String message = mainDescriptor.getMinimumMappingsVersionMessage("auto-create index");
+                            final String message = mainDescriptor.getMinimumMappingsVersionMessage(
+                                "auto-create index",
+                                requiredMinimumMappingVersion
+                            );
                             logger.warn(message);
                             throw new IllegalStateException(message);
                         }

server/src/main/java/org/elasticsearch/action/admin/indices/create/TransportCreateIndexAction.java

@@ -135,11 +135,10 @@ protected void masterOperation(
         // We check this via the request's origin. Eventually, `SystemIndexManager` will reconfigure
         // the index to the latest settings.
         if (isManagedSystemIndex && Strings.isNullOrEmpty(request.origin())) {
-            final SystemIndexDescriptor descriptor = mainDescriptor.getDescriptorCompatibleWith(
-                state.getMinSystemIndexMappingVersions().get(mainDescriptor.getPrimaryIndex())
-            );
+            final var requiredMinimumMappingVersion = state.getMinSystemIndexMappingVersions().get(mainDescriptor.getPrimaryIndex());
+            final SystemIndexDescriptor descriptor = mainDescriptor.getDescriptorCompatibleWith(requiredMinimumMappingVersion);
             if (descriptor == null) {
-                final String message = mainDescriptor.getMinimumMappingsVersionMessage("create index");
+                final String message = mainDescriptor.getMinimumMappingsVersionMessage("create index", requiredMinimumMappingVersion);
                 logger.warn(message);
                 listener.onFailure(new IllegalStateException(message));
                 return;

server/src/main/java/org/elasticsearch/indices/SystemIndexDescriptor.java

@@ -316,7 +316,7 @@ protected SystemIndexDescriptor(
                 if (prior.primaryIndex.equals(primaryIndex) == false) {
                     throw new IllegalArgumentException("primary index must be the same");
                 }
-                if (prior.aliasName.equals(aliasName) == false) {
+                if (Objects.equals(prior.aliasName, aliasName) == false) {
                     throw new IllegalArgumentException("alias name must be the same");
                 }
             }
@@ -512,16 +512,21 @@ public MappingsVersion getMappingsVersion() {
      * @param cause the action being attempted that triggered the check. Used in the error message.
      * @return the standardized error message
      */
-    public String getMinimumMappingsVersionMessage(String cause) {
+    public String getMinimumMappingsVersionMessage(String cause, MappingsVersion requiredMinimumMappingVersion) {
         Objects.requireNonNull(cause);
         final MappingsVersion actualMinimumMappingsVersion = priorSystemIndexDescriptors.isEmpty()
             ? getMappingsVersion()
             : priorSystemIndexDescriptors.get(priorSystemIndexDescriptors.size() - 1).mappingsVersion;
         return Strings.format(
-            "[%s] failed - system index [%s] requires all data and master nodes to have mappings versions at least of version [%s]",
+            "[%s] failed - requested creation of system index [%s] with version [%s], while this cluster minimum supported version is "
+                + "[%s]. For the cluster to support version [%s], ensure that the system index descriptor for [%s] includes a prior "
+                + "definition for that version.",
             cause,
             this.getPrimaryIndex(),
-            actualMinimumMappingsVersion
+            requiredMinimumMappingVersion,
+            actualMinimumMappingsVersion,
+            requiredMinimumMappingVersion,
+            this.getPrimaryIndex()
         );
     }
 

x-pack/plugin/security/src/main/java/org/elasticsearch/xpack/security/support/SecurityIndexManager.java

@@ -652,7 +652,10 @@ public void prepareIndexIfNeededThenExecute(final Consumer<Exception> consumer,
                 );
 
                 if (descriptorForVersion == null) {
-                    final String error = systemIndexDescriptor.getMinimumMappingsVersionMessage("create index");
+                    final String error = systemIndexDescriptor.getMinimumMappingsVersionMessage(
+                        "create index",
+                        state.minClusterMappingVersion
+                    );
                     consumer.accept(new IllegalStateException(error));
                 } else {
                     logger.info(
@@ -703,7 +706,10 @@ public void onFailure(Exception e) {
                 );
 
                 if (descriptorForVersion == null) {
-                    final String error = systemIndexDescriptor.getMinimumMappingsVersionMessage("updating mapping");
+                    final String error = systemIndexDescriptor.getMinimumMappingsVersionMessage(
+                        "updating mapping",
+                        state.minClusterMappingVersion
+                    );
                     consumer.accept(new IllegalStateException(error));
                 } else {
                     logger.info(

x-pack/plugin/security/src/test/java/org/elasticsearch/xpack/security/support/SecurityIndexManagerTests.java

@@ -82,6 +82,7 @@
 import static org.hamcrest.Matchers.not;
 import static org.hamcrest.Matchers.notNullValue;
 import static org.hamcrest.Matchers.nullValue;
+import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyString;
 import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.doReturn;
@@ -434,7 +435,7 @@ public void testCannotUpdateIndexMappingsWhenMinMappingVersionTooLow() {
         final AtomicReference<Exception> prepareException = new AtomicReference<>(null);
 
         // Hard-code a failure here.
-        doReturn("Nope").when(descriptorSpy).getMinimumMappingsVersionMessage(anyString());
+        doReturn("Nope").when(descriptorSpy).getMinimumMappingsVersionMessage(anyString(), any());
         doReturn(null).when(descriptorSpy)
             .getDescriptorCompatibleWith(eq(new SystemIndexDescriptor.MappingsVersion(SecurityMainIndexMappingVersion.latest().id(), 0)));