/*
* SPDX-License-Identifier: Apache-2.0
*
* The OpenSearch Contributors require contributions made to
* this file be licensed under the Apache-2.0 license or a
* compatible open source license.
*/
/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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.
*/
/*
* Modifications Copyright OpenSearch Contributors. See
* GitHub history for details.
*/
package org.opensearch.transport;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.opensearch.action.ActionListener;
import org.opensearch.action.OriginalIndices;
import org.opensearch.action.support.GroupedActionListener;
import org.opensearch.action.support.IndicesOptions;
import org.opensearch.client.Client;
import org.opensearch.cluster.node.DiscoveryNode;
import org.opensearch.cluster.node.DiscoveryNodeRole;
import org.opensearch.common.Strings;
import org.opensearch.common.settings.ClusterSettings;
import org.opensearch.common.settings.Setting;
import org.opensearch.common.settings.Settings;
import org.opensearch.common.unit.TimeValue;
import org.opensearch.common.util.concurrent.ConcurrentCollections;
import org.opensearch.common.util.concurrent.CountDown;
import org.opensearch.common.util.io.IOUtils;
import org.opensearch.threadpool.ThreadPool;
import java.io.Closeable;
import java.io.IOException;
import java.util.Arrays;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
import java.util.function.BiFunction;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.stream.Stream;
import static org.opensearch.common.settings.Setting.boolSetting;
import static org.opensearch.common.settings.Setting.timeSetting;
/**
* Basic service for accessing remote clusters via gateway nodes
*
* @opensearch.internal
*/
public final class RemoteClusterService extends RemoteClusterAware implements Closeable {
private final Logger logger = LogManager.getLogger(RemoteClusterService.class);
/**
* The initial connect timeout for remote cluster connections
*/
public static final Setting<TimeValue> REMOTE_INITIAL_CONNECTION_TIMEOUT_SETTING = Setting.positiveTimeSetting(
"cluster.remote.initial_connect_timeout",
TimeValue.timeValueSeconds(30),
Setting.Property.NodeScope
);
/**
* The name of a node attribute to select nodes that should be connected to in the remote cluster.
* For instance a node can be configured with {@code node.attr.gateway: true} in order to be eligible as a gateway node between
* clusters. In that case {@code cluster.remote.node.attr: gateway} can be used to filter out other nodes in the remote cluster.
* The value of the setting is expected to be a boolean, {@code true} for nodes that can become gateways, {@code false} otherwise.
*/
public static final Setting<String> REMOTE_NODE_ATTRIBUTE = Setting.simpleString(
"cluster.remote.node.attr",
Setting.Property.NodeScope
);
/**
* If <code>true</code> connecting to remote clusters is supported on this node. If <code>false</code> this node will not establish
* connections to any remote clusters configured. Search requests executed against this node (where this node is the coordinating node)
* will fail if remote cluster syntax is used as an index pattern. The default is <code>true</code>
*/
public static final Setting<Boolean> ENABLE_REMOTE_CLUSTERS = Setting.boolSetting(
"cluster.remote.connect",
true,
Setting.Property.Deprecated,
Setting.Property.NodeScope
);
public static final Setting.AffixSetting<Boolean> REMOTE_CLUSTER_SKIP_UNAVAILABLE = Setting.affixKeySetting(
"cluster.remote.",
"skip_unavailable",
(ns, key) -> boolSetting(key, false, new RemoteConnectionEnabled<>(ns, key), Setting.Property.Dynamic, Setting.Property.NodeScope)
);
public static final Setting.AffixSetting<TimeValue> REMOTE_CLUSTER_PING_SCHEDULE = Setting.affixKeySetting(
"cluster.remote.",
"transport.ping_schedule",
(ns, key) -> timeSetting(
key,
TransportSettings.PING_SCHEDULE,
new RemoteConnectionEnabled<>(ns, key),
Setting.Property.Dynamic,
Setting.Property.NodeScope
)
);
public static final Setting.AffixSetting<Boolean> REMOTE_CLUSTER_COMPRESS = Setting.affixKeySetting(
"cluster.remote.",
"transport.compress",
(ns, key) -> boolSetting(
key,
TransportSettings.TRANSPORT_COMPRESS,
new RemoteConnectionEnabled<>(ns, key),
Setting.Property.Dynamic,
Setting.Property.NodeScope
)
);
private final boolean enabled;
public boolean isEnabled() {
return enabled;
}
private final TransportService transportService;
private final Map<String, RemoteClusterConnection> remoteClusters = ConcurrentCollections.newConcurrentMap();
RemoteClusterService(Settings settings, TransportService transportService) {
super(settings);
this.enabled = DiscoveryNode.isRemoteClusterClient(settings);
this.transportService = transportService;
}
/**
* Returns <code>true</code> if at least one remote cluster is configured
*/
public boolean isCrossClusterSearchEnabled() {
return remoteClusters.isEmpty() == false;
}
boolean isRemoteNodeConnected(final String remoteCluster, final DiscoveryNode node) {
return remoteClusters.get(remoteCluster).isNodeConnected(node);
}
public Map<String, OriginalIndices> groupIndices(IndicesOptions indicesOptions, String[] indices, Predicate<String> indexExists) {
Map<String, OriginalIndices> originalIndicesMap = new HashMap<>();
if (isCrossClusterSearchEnabled()) {
final Map<String, List<String>> groupedIndices = groupClusterIndices(getRemoteClusterNames(), indices, indexExists);
if (groupedIndices.isEmpty()) {
// search on _all in the local cluster if neither local indices nor remote indices were specified
originalIndicesMap.put(LOCAL_CLUSTER_GROUP_KEY, new OriginalIndices(Strings.EMPTY_ARRAY, indicesOptions));
} else {
for (Map.Entry<String, List<String>> entry : groupedIndices.entrySet()) {
String clusterAlias = entry.getKey();
List<String> originalIndices = entry.getValue();
originalIndicesMap.put(clusterAlias, new OriginalIndices(originalIndices.toArray(new String[0]), indicesOptions));
}
}
} else {
originalIndicesMap.put(LOCAL_CLUSTER_GROUP_KEY, new OriginalIndices(indices, indicesOptions));
}
return originalIndicesMap;
}
/**
* Returns <code>true</code> iff the given cluster is configured as a remote cluster. Otherwise <code>false</code>
*/
boolean isRemoteClusterRegistered(String clusterName) {
return remoteClusters.containsKey(clusterName);
}
/**
* Returns the registered remote cluster names.
*/
public Set<String> getRegisteredRemoteClusterNames() {
// remoteClusters is unmodifiable so its key set will be unmodifiable too
return remoteClusters.keySet();
}
/**
* Returns a connection to the given node on the given remote cluster
*
* @throws IllegalArgumentException if the remote cluster is unknown
*/
public Transport.Connection getConnection(DiscoveryNode node, String cluster) {
return getRemoteClusterConnection(cluster).getConnection(node);
}
/**
* Ensures that the given cluster alias is connected. If the cluster is connected this operation
* will invoke the listener immediately.
*/
void ensureConnected(String clusterAlias, ActionListener<Void> listener) {
getRemoteClusterConnection(clusterAlias).ensureConnected(listener);
}
/**
* Returns whether the cluster identified by the provided alias is configured to be skipped when unavailable
*/
public boolean isSkipUnavailable(String clusterAlias) {
return getRemoteClusterConnection(clusterAlias).isSkipUnavailable();
}
public Transport.Connection getConnection(String cluster) {
return getRemoteClusterConnection(cluster).getConnection();
}
RemoteClusterConnection getRemoteClusterConnection(String cluster) {
if (enabled == false) {
throw new IllegalArgumentException(
"this node does not have the " + DiscoveryNodeRole.REMOTE_CLUSTER_CLIENT_ROLE.roleName() + " role"
);
}
RemoteClusterConnection connection = remoteClusters.get(cluster);
if (connection == null) {
throw new NoSuchRemoteClusterException(cluster);
}
return connection;
}
Set<String> getRemoteClusterNames() {
return this.remoteClusters.keySet();
}
@Override
public void listenForUpdates(ClusterSettings clusterSettings) {
super.listenForUpdates(clusterSettings);
clusterSettings.addAffixUpdateConsumer(REMOTE_CLUSTER_SKIP_UNAVAILABLE, this::updateSkipUnavailable, (alias, value) -> {});
}
private synchronized void updateSkipUnavailable(String clusterAlias, Boolean skipUnavailable) {
RemoteClusterConnection remote = this.remoteClusters.get(clusterAlias);
if (remote != null) {
remote.updateSkipUnavailable(skipUnavailable);
}
}
@Override
protected void updateRemoteCluster(String clusterAlias, Settings settings) {
CountDownLatch latch = new CountDownLatch(1);
updateRemoteCluster(clusterAlias, settings, ActionListener.wrap(latch::countDown));
try {
// Wait 10 seconds for a connections. We must use a latch instead of a future because we
// are on the cluster state thread and our custom future implementation will throw an
// assertion.
if (latch.await(10, TimeUnit.SECONDS) == false) {
logger.warn("failed to connect to new remote cluster {} within {}", clusterAlias, TimeValue.timeValueSeconds(10));
}
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
}
/**
* This method updates the list of remote clusters. It's intended to be used as an update consumer on the settings infrastructure
*
* @param clusterAlias a cluster alias to discovery node mapping representing the remote clusters seeds nodes
* @param newSettings the updated settings for the remote connection
* @param listener a listener invoked once every configured cluster has been connected to
*/
synchronized void updateRemoteCluster(String clusterAlias, Settings newSettings, ActionListener<Void> listener) {
if (LOCAL_CLUSTER_GROUP_KEY.equals(clusterAlias)) {
throw new IllegalArgumentException("remote clusters must not have the empty string as its key");
}
RemoteClusterConnection remote = this.remoteClusters.get(clusterAlias);
if (RemoteConnectionStrategy.isConnectionEnabled(clusterAlias, newSettings) == false) {
try {
IOUtils.close(remote);
} catch (IOException e) {
logger.warn("failed to close remote cluster connections for cluster: " + clusterAlias, e);
}
remoteClusters.remove(clusterAlias);
listener.onResponse(null);
return;
}
if (remote == null) {
// this is a new cluster we have to add a new representation
Settings finalSettings = Settings.builder().put(this.settings, false).put(newSettings, false).build();
remote = new RemoteClusterConnection(finalSettings, clusterAlias, transportService);
remoteClusters.put(clusterAlias, remote);
remote.ensureConnected(listener);
} else if (remote.shouldRebuildConnection(newSettings)) {
// Changes to connection configuration. Must tear down existing connection
try {
IOUtils.close(remote);
} catch (IOException e) {
logger.warn("failed to close remote cluster connections for cluster: " + clusterAlias, e);
}
remoteClusters.remove(clusterAlias);
Settings finalSettings = Settings.builder().put(this.settings, false).put(newSettings, false).build();
remote = new RemoteClusterConnection(finalSettings, clusterAlias, transportService);
remoteClusters.put(clusterAlias, remote);
remote.ensureConnected(listener);
} else {
// No changes to connection configuration.
listener.onResponse(null);
}
}
/**
* Connects to all remote clusters in a non-blocking fashion. This should be called on node startup to establish an initial connection
* to all configured seed nodes.
*/
void initializeRemoteClusters(ActionListener<Void> listener) {
Set<String> enabledClusters = RemoteClusterAware.getEnabledRemoteClusters(settings);
if (enabledClusters.isEmpty()) {
listener.onResponse(null);
return;
}
GroupedActionListener<Void> groupListener = new GroupedActionListener<>(
ActionListener.wrap(r -> listener.onResponse(null), listener::onFailure),
enabledClusters.size()
);
for (String clusterAlias : enabledClusters) {
updateRemoteCluster(clusterAlias, settings, groupListener);
}
}
@Override
public void close() throws IOException {
IOUtils.close(remoteClusters.values());
}
public Stream<RemoteConnectionInfo> getRemoteConnectionInfos() {
return remoteClusters.values().stream().map(RemoteClusterConnection::getConnectionInfo);
}
/**
* Collects all nodes of the given clusters and returns / passes a (clusterAlias, nodeId) to {@link DiscoveryNode}
* function on success.
*/
public void collectNodes(Set<String> clusters, ActionListener<BiFunction<String, String, DiscoveryNode>> listener) {
if (enabled == false) {
throw new IllegalArgumentException(
"this node does not have the " + DiscoveryNodeRole.REMOTE_CLUSTER_CLIENT_ROLE.roleName() + " role"
);
}
Map<String, RemoteClusterConnection> remoteClusters = this.remoteClusters;
for (String cluster : clusters) {
if (remoteClusters.containsKey(cluster) == false) {
listener.onFailure(new NoSuchRemoteClusterException(cluster));
return;
}
}
final Map<String, Function<String, DiscoveryNode>> clusterMap = new HashMap<>();
CountDown countDown = new CountDown(clusters.size());
Function<String, DiscoveryNode> nullFunction = s -> null;
for (final String cluster : clusters) {
RemoteClusterConnection connection = remoteClusters.get(cluster);
connection.collectNodes(new ActionListener<Function<String, DiscoveryNode>>() {
@Override
public void onResponse(Function<String, DiscoveryNode> nodeLookup) {
synchronized (clusterMap) {
clusterMap.put(cluster, nodeLookup);
}
if (countDown.countDown()) {
listener.onResponse((clusterAlias, nodeId) -> clusterMap.getOrDefault(clusterAlias, nullFunction).apply(nodeId));
}
}
@Override
public void onFailure(Exception e) {
if (countDown.fastForward()) { // we need to check if it's true since we could have multiple failures
listener.onFailure(e);
}
}
});
}
}
/**
* Returns a client to the remote cluster if the given cluster alias exists.
*
* @param threadPool the {@link ThreadPool} for the client
* @param clusterAlias the cluster alias the remote cluster is registered under
* @throws IllegalArgumentException if the given clusterAlias doesn't exist
*/
public Client getRemoteClusterClient(ThreadPool threadPool, String clusterAlias) {
if (transportService.getRemoteClusterService().isEnabled() == false) {
throw new IllegalArgumentException(
"this node does not have the " + DiscoveryNodeRole.REMOTE_CLUSTER_CLIENT_ROLE.roleName() + " role"
);
}
if (transportService.getRemoteClusterService().getRemoteClusterNames().contains(clusterAlias) == false) {
throw new NoSuchRemoteClusterException(clusterAlias);
}
return new RemoteClusterAwareClient(settings, threadPool, transportService, clusterAlias);
}
Collection<RemoteClusterConnection> getConnections() {
return remoteClusters.values();
}
/**
* Internal class to hold cluster alias and key and track a remote connection
*
* @opensearch.internal
*/
private static class RemoteConnectionEnabled<T> implements Setting.Validator<T> {
private final String clusterAlias;
private final String key;
private RemoteConnectionEnabled(String clusterAlias, String key) {
this.clusterAlias = clusterAlias;
this.key = key;
}
@Override
public void validate(T value) {}
@Override
public void validate(T value, Map<Setting<?>, Object> settings, boolean isPresent) {
if (isPresent && RemoteConnectionStrategy.isConnectionEnabled(clusterAlias, settings) == false) {
throw new IllegalArgumentException("Cannot configure setting [" + key + "] if remote cluster is not enabled.");
}
}
@Override
public Iterator<Setting<?>> settings() {
return Stream.concat(
Stream.of(RemoteConnectionStrategy.REMOTE_CONNECTION_MODE.getConcreteSettingForNamespace(clusterAlias)),
settingsStream()
).iterator();
}
private Stream<Setting<?>> settingsStream() {
return Arrays.stream(RemoteConnectionStrategy.ConnectionStrategy.values())
.flatMap(strategy -> strategy.getEnablementSettings().get())
.map(as -> as.getConcreteSettingForNamespace(clusterAlias));
}
};
}