SOLR-17269: Do not publish synthetic solr core (of Coordinator node) to ZK

solr/core/src/java/org/apache/solr/cloud/ZkConfigSetService.java

@@ -26,12 +26,9 @@
 import java.util.Map;
 import java.util.Objects;
 import org.apache.solr.client.solrj.cloud.SolrCloudManager;
-import org.apache.solr.cloud.api.collections.CreateCollectionCmd;
 import org.apache.solr.common.SolrException;
 import org.apache.solr.common.cloud.SolrZkClient;
 import org.apache.solr.common.cloud.ZkMaintenanceUtils;
-import org.apache.solr.common.cloud.ZkStateReader;
-import org.apache.solr.common.cloud.ZooKeeperException;
 import org.apache.solr.common.util.NamedList;
 import org.apache.solr.common.util.Utils;
 import org.apache.solr.core.ConfigSetProperties;
@@ -71,36 +68,18 @@ public ZkConfigSetService(SolrZkClient zkClient) {
 
  @Override
  public SolrResourceLoader createCoreResourceLoader(CoreDescriptor cd) {
- final String colName = cd.getCollectionName();
-
- // For back compat with cores that can create collections without the collections API
- try {
- if (!zkClient.exists(ZkStateReader.COLLECTIONS_ZKNODE + "/" + colName, true)) {
- // TODO remove this functionality or maybe move to a CLI mechanism
- log.warn(
- "Auto-creating collection (in ZK) from core descriptor (on disk). This feature may go away!");
- CreateCollectionCmd.createCollectionZkNode(
- zkController.getSolrCloudManager().getDistribStateManager(),
- colName,
- cd.getCloudDescriptor().getParams(),
- zkController.getCoreContainer().getConfigSetService());
- }
- } catch (InterruptedException e) {
- Thread.currentThread().interrupt();
- throw new ZooKeeperException(
- SolrException.ErrorCode.SERVER_ERROR, "Interrupted auto-creating collection", e);
- } catch (KeeperException e) {
- throw new ZooKeeperException(
- SolrException.ErrorCode.SERVER_ERROR, "Failure auto-creating collection", e);
+ // Currently, cd.getConfigSet() is always null. Except that it's explicitly set by
+ // {@link org.apache.solr.core.SyntheticSolrCore}.
+ // Should we consider setting it for all cores as a part of CoreDescriptor creation/loading
+ // process?
+ if (cd.getConfigSet() == null) {
+ String configSetName =
+ zkController.getClusterState().getCollection(cd.getCollectionName()).getConfigName();
+ cd.setConfigSet(configSetName);
  }
 
- // The configSet is read from ZK and populated. Ignore CD's pre-existing configSet; only
- // populated in standalone
- String configSetName = zkController.getClusterState().getCollection(colName).getConfigName();
- cd.setConfigSet(configSetName);
-
  return new ZkSolrResourceLoader(
- cd.getInstanceDir(), configSetName, parentLoader.getClassLoader(), zkController);
+ cd.getInstanceDir(), cd.getConfigSet(), parentLoader.getClassLoader(), zkController);
  }
 
  @Override

solr/core/src/java/org/apache/solr/core/SolrCore.java

@@ -1235,7 +1235,7 @@ private SolrCore(
  }
 
  /** Set UpdateLog to buffer updates if the slice is in construction. */
- private void bufferUpdatesIfConstructing(CoreDescriptor coreDescriptor) {
+ protected void bufferUpdatesIfConstructing(CoreDescriptor coreDescriptor) {
 
  if (coreContainer != null && coreContainer.isZooKeeperAware()) {
  if (reqHandlers.get("/get") == null) {

solr/core/src/java/org/apache/solr/core/SyntheticSolrCore.java

@@ -0,0 +1,75 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.solr.core;
+
+import java.nio.file.Path;
+import java.util.Map;
+import org.apache.solr.common.SolrException;
+import org.apache.solr.common.params.CoreAdminParams;
+import org.apache.solr.rest.RestManager;
+
+/**
+ * A synthetic core that is created only in memory and not registered against Zookeeper.
+ *
+ * <p>This is only used in Coordinator node to support a subset of SolrCore functionalities required
+ * by Coordinator operations such as aggregating and writing out response and providing configset
+ * info.
+ *
+ * <p>There should only be one instance of SyntheticSolrCore per configset
+ */
+public class SyntheticSolrCore extends SolrCore {
+ public SyntheticSolrCore(CoreContainer coreContainer, CoreDescriptor cd, ConfigSet configSet) {
+ super(coreContainer, cd, configSet);
+ }
+
+ public static SyntheticSolrCore createAndRegisterCore(
+ CoreContainer coreContainer, String syntheticCoreName, String configSetName) {
+ Map<String, String> coreProps = Map.of(CoreAdminParams.COLLECTION, syntheticCoreName);
+
+ CoreDescriptor syntheticCoreDescriptor =
+ new CoreDescriptor(
+ syntheticCoreName,
+ Path.of(coreContainer.getSolrHome(), syntheticCoreName),
+ coreProps,
+ coreContainer.getContainerProperties(),
+ coreContainer.getZkController());
+ syntheticCoreDescriptor.setConfigSet(configSetName);
+ ConfigSet coreConfig =
+ coreContainer.getConfigSetService().loadConfigSet(syntheticCoreDescriptor);
+ syntheticCoreDescriptor.setConfigSetTrusted(coreConfig.isTrusted());
+ SyntheticSolrCore syntheticCore =
+ new SyntheticSolrCore(coreContainer, syntheticCoreDescriptor, coreConfig);
+ coreContainer.registerCore(syntheticCoreDescriptor, syntheticCore, false, false);
+
+ return syntheticCore;
+ }
+
+ @Override
+ protected void bufferUpdatesIfConstructing(CoreDescriptor coreDescriptor) {
+ // no updates to SyntheticSolrCore
+ }
+
+ @Override
+ protected RestManager initRestManager() throws SolrException {
+ // returns an initialized RestManager. As init routines requires reading configname of the
+ // core's collection from ZK
+ // which synthetic core is not registered in ZK.
+ // We do not expect RestManager ops on Coordinator Nodes
+ return new RestManager();
+ }
+}