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/*
* 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.
*/
package org.elasticsearch.cluster.routing.allocation.decider;
import org.elasticsearch.cluster.ClusterState;
import org.elasticsearch.cluster.routing.ShardRouting;
import org.elasticsearch.cluster.routing.allocation.RoutingAllocation;
import org.elasticsearch.cluster.settings.Validator;
import org.elasticsearch.common.inject.Inject;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.node.settings.NodeSettingsService;
import java.util.Locale;
/**
* This {@link AllocationDecider} controls re-balancing operations based on the
* cluster wide active shard state. This decided can not be configured in
* real-time and should be pre-cluster start via
* cluster.routing.allocation.allow_rebalance. This setting respects the following
* values:
*
* - indices_primaries_active - Re-balancing is allowed only once all
* primary shards on all indices are active.
*
* - indices_all_active - Re-balancing is allowed only once all
* shards on all indices are active.
*
* - always - Re-balancing is allowed once a shard replication group
* is active
*
*/
public class ClusterRebalanceAllocationDecider extends AllocationDecider {
public static final String NAME = "cluster_rebalance";
public static final String CLUSTER_ROUTING_ALLOCATION_ALLOW_REBALANCE = "cluster.routing.allocation.allow_rebalance";
public static final Validator ALLOCATION_ALLOW_REBALANCE_VALIDATOR = new Validator() {
@Override
public String validate(String setting, String value, ClusterState clusterState) {
try {
ClusterRebalanceType.parseString(value);
return null;
} catch (IllegalArgumentException e) {
return "the value of " + setting + " must be one of: [always, indices_primaries_active, indices_all_active]";
}
}
};
/**
* An enum representation for the configured re-balance type.
*/
public static enum ClusterRebalanceType {
/**
* Re-balancing is allowed once a shard replication group is active
*/
ALWAYS,
/**
* Re-balancing is allowed only once all primary shards on all indices are active.
*/
INDICES_PRIMARIES_ACTIVE,
/**
* Re-balancing is allowed only once all shards on all indices are active.
*/
INDICES_ALL_ACTIVE;
public static ClusterRebalanceType parseString(String typeString) {
if ("always".equalsIgnoreCase(typeString)) {
return ClusterRebalanceType.ALWAYS;
} else if ("indices_primaries_active".equalsIgnoreCase(typeString) || "indicesPrimariesActive".equalsIgnoreCase(typeString)) {
return ClusterRebalanceType.INDICES_PRIMARIES_ACTIVE;
} else if ("indices_all_active".equalsIgnoreCase(typeString) || "indicesAllActive".equalsIgnoreCase(typeString)) {
return ClusterRebalanceType.INDICES_ALL_ACTIVE;
}
throw new IllegalArgumentException("Illegal value for " + CLUSTER_ROUTING_ALLOCATION_ALLOW_REBALANCE + ": " + typeString);
}
}
private ClusterRebalanceType type;
@Inject
public ClusterRebalanceAllocationDecider(Settings settings, NodeSettingsService nodeSettingsService) {
super(settings);
String allowRebalance = settings.get(CLUSTER_ROUTING_ALLOCATION_ALLOW_REBALANCE, "indices_all_active");
try {
type = ClusterRebalanceType.parseString(allowRebalance);
} catch (IllegalStateException e) {
logger.warn("[{}] has a wrong value {}, defaulting to 'indices_all_active'", CLUSTER_ROUTING_ALLOCATION_ALLOW_REBALANCE, allowRebalance);
type = ClusterRebalanceType.INDICES_ALL_ACTIVE;
}
logger.debug("using [{}] with [{}]", CLUSTER_ROUTING_ALLOCATION_ALLOW_REBALANCE, type.toString().toLowerCase(Locale.ROOT));
nodeSettingsService.addListener(new ApplySettings());
}
class ApplySettings implements NodeSettingsService.Listener {
@Override
public void onRefreshSettings(Settings settings) {
String newAllowRebalance = settings.get(CLUSTER_ROUTING_ALLOCATION_ALLOW_REBALANCE, null);
if (newAllowRebalance != null) {
ClusterRebalanceType newType = null;
try {
newType = ClusterRebalanceType.parseString(newAllowRebalance);
} catch (IllegalArgumentException e) {
// ignore
}
if (newType != null && newType != ClusterRebalanceAllocationDecider.this.type) {
logger.info("updating [{}] from [{}] to [{}]", CLUSTER_ROUTING_ALLOCATION_ALLOW_REBALANCE,
ClusterRebalanceAllocationDecider.this.type.toString().toLowerCase(Locale.ROOT),
newType.toString().toLowerCase(Locale.ROOT));
ClusterRebalanceAllocationDecider.this.type = newType;
}
}
}
}
@Override
public Decision canRebalance(ShardRouting shardRouting, RoutingAllocation allocation) {
return canRebalance(allocation);
}
@Override
public Decision canRebalance(RoutingAllocation allocation) {
if (type == ClusterRebalanceType.INDICES_PRIMARIES_ACTIVE) {
// check if there are unassigned primaries.
if (allocation.routingNodes().hasUnassignedPrimaries()) {
return allocation.decision(Decision.NO, NAME, "cluster has unassigned primary shards");
}
// check if there are initializing primaries that don't have a relocatingNodeId entry.
if (allocation.routingNodes().hasInactivePrimaries()) {
return allocation.decision(Decision.NO, NAME, "cluster has inactive primary shards");
}
return allocation.decision(Decision.YES, NAME, "all primary shards are active");
}
if (type == ClusterRebalanceType.INDICES_ALL_ACTIVE) {
// check if there are unassigned shards.
if (allocation.routingNodes().hasUnassignedShards()) {
return allocation.decision(Decision.NO, NAME, "cluster has unassigned shards");
}
// in case all indices are assigned, are there initializing shards which
// are not relocating?
if (allocation.routingNodes().hasInactiveShards()) {
return allocation.decision(Decision.NO, NAME, "cluster has inactive shards");
}
}
// type == Type.ALWAYS
return allocation.decision(Decision.YES, NAME, "all shards are active");
}
}