Add assertion that system index version hashes match (should fail bwc)

server/src/main/java/org/elasticsearch/cluster/coordination/NodeJoinExecutor.java

@@ -29,6 +29,7 @@
 import org.elasticsearch.features.FeatureService;
 import org.elasticsearch.index.IndexVersion;
 import org.elasticsearch.index.IndexVersions;
+import org.elasticsearch.indices.SystemIndexDescriptor;
 import org.elasticsearch.persistent.PersistentTasksCustomMetadata;
 
 import java.util.ArrayList;
@@ -158,6 +159,7 @@ public ClusterState execute(BatchExecutionContext<JoinTask> batchExecutionContex
  } else {
  try {
  CompatibilityVersions compatibilityVersions = nodeJoinTask.compatibilityVersions();
+ assert systemIndexVersionConsistent(compatibilityVersions.systemIndexMappingsVersion(), compatibilityVersionsMap);
  Set<String> features = nodeJoinTask.features();
  if (enforceVersionBarrier) {
  ensureVersionBarrier(node.getVersion(), minClusterNodeVersion);
@@ -261,6 +263,25 @@ public ClusterState execute(BatchExecutionContext<JoinTask> batchExecutionContex
  }
  }
 
+ private boolean systemIndexVersionConsistent(
+ Map<String, SystemIndexDescriptor.MappingsVersion> newMappingsVersions,
+ Map<String, CompatibilityVersions> existingCompatibilityVersions
+ ) {
+ for (Map.Entry<String, CompatibilityVersions> nodeCompatibility : existingCompatibilityVersions.entrySet()) {
+ Map<String, SystemIndexDescriptor.MappingsVersion> existingVersions = nodeCompatibility.getValue().systemIndexMappingsVersion();
+ for (Map.Entry<String, SystemIndexDescriptor.MappingsVersion> existingMappingVersion : existingVersions.entrySet()) {
+ String indexName = existingMappingVersion.getKey();
+ if (newMappingsVersions.containsKey(indexName)
+ && existingMappingVersion.getValue().version() == newMappingsVersions.get(indexName).version()
+ && existingMappingVersion.getValue().hash() != newMappingsVersions.get(indexName).hash()) {
+ // log warning message?
+ return false;
+ }
+ }
+ }
+ return true;
+ }
+
  protected ClusterState.Builder becomeMasterAndTrimConflictingNodes(
  ClusterState currentState,
  List<? extends TaskContext<JoinTask>> taskContexts,