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 * 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.
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package org.elasticsearch.cluster.allocation;

import org.apache.logging.log4j.Logger;
import org.apache.lucene.util.IOUtils;
import org.elasticsearch.action.admin.cluster.health.ClusterHealthResponse;
import org.elasticsearch.action.admin.cluster.reroute.ClusterRerouteResponse;
import org.elasticsearch.action.support.ActiveShardCount;
import org.elasticsearch.action.support.WriteRequest.RefreshPolicy;
import org.elasticsearch.cluster.ClusterState;
import org.elasticsearch.cluster.health.ClusterHealthStatus;
import org.elasticsearch.cluster.node.DiscoveryNode;
import org.elasticsearch.cluster.routing.ShardRouting;
import org.elasticsearch.cluster.routing.ShardRoutingState;
import org.elasticsearch.cluster.routing.allocation.RerouteExplanation;
import org.elasticsearch.cluster.routing.allocation.RoutingExplanations;
import org.elasticsearch.cluster.routing.allocation.command.AllocateEmptyPrimaryAllocationCommand;
import org.elasticsearch.cluster.routing.allocation.command.MoveAllocationCommand;
import org.elasticsearch.cluster.routing.allocation.decider.Decision;
import org.elasticsearch.cluster.routing.allocation.decider.EnableAllocationDecider;
import org.elasticsearch.cluster.routing.allocation.decider.EnableAllocationDecider.Allocation;
import org.elasticsearch.cluster.routing.allocation.decider.ThrottlingAllocationDecider;
import org.elasticsearch.common.Priority;
import org.elasticsearch.common.io.FileSystemUtils;
import org.elasticsearch.common.logging.Loggers;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.common.unit.TimeValue;
import org.elasticsearch.env.NodeEnvironment;
import org.elasticsearch.index.Index;
import org.elasticsearch.index.shard.ShardId;
import org.elasticsearch.test.ESIntegTestCase;
import org.elasticsearch.test.ESIntegTestCase.ClusterScope;
import org.elasticsearch.test.ESIntegTestCase.Scope;
import org.elasticsearch.test.InternalTestCluster;

import java.nio.file.Path;
import java.util.Arrays;
import java.util.List;

import static org.elasticsearch.cluster.metadata.IndexMetaData.SETTING_BLOCKS_METADATA;
import static org.elasticsearch.cluster.metadata.IndexMetaData.SETTING_BLOCKS_READ;
import static org.elasticsearch.cluster.metadata.IndexMetaData.SETTING_BLOCKS_WRITE;
import static org.elasticsearch.cluster.metadata.IndexMetaData.SETTING_READ_ONLY;
import static org.elasticsearch.cluster.routing.allocation.decider.EnableAllocationDecider.CLUSTER_ROUTING_ALLOCATION_ENABLE_SETTING;
import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcked;
import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertBlocked;
import static org.hamcrest.Matchers.equalTo;
import static org.hamcrest.Matchers.hasSize;

@ClusterScope(scope = Scope.TEST, numDataNodes = 0)
public class ClusterRerouteIT extends ESIntegTestCase {
    private final Logger logger = Loggers.getLogger(ClusterRerouteIT.class);

    public void testRerouteWithCommands_disableAllocationSettings() throws Exception {
        Settings commonSettings = Settings.builder()
                .put(EnableAllocationDecider.CLUSTER_ROUTING_ALLOCATION_ENABLE_SETTING.getKey(), "none")
                .put(EnableAllocationDecider.CLUSTER_ROUTING_REBALANCE_ENABLE_SETTING.getKey(), "none")
                .build();
        rerouteWithCommands(commonSettings);
    }

    public void testRerouteWithCommands_enableAllocationSettings() throws Exception {
        Settings commonSettings = Settings.builder()
                .put(CLUSTER_ROUTING_ALLOCATION_ENABLE_SETTING.getKey(), Allocation.NONE.name())
                .build();
        rerouteWithCommands(commonSettings);
    }

    private void rerouteWithCommands(Settings commonSettings) throws Exception {
        List<String> nodesIds = internalCluster().startNodes(2, commonSettings);
        final String node_1 = nodesIds.get(0);
        final String node_2 = nodesIds.get(1);

        logger.info("--> create an index with 1 shard, 1 replica, nothing should allocate");
        client().admin().indices().prepareCreate("test").setWaitForActiveShards(ActiveShardCount.NONE)
                .setSettings(Settings.builder().put("index.number_of_shards", 1))
                .execute().actionGet();

        ClusterState state = client().admin().cluster().prepareState().execute().actionGet().getState();
        assertThat(state.getRoutingNodes().unassigned().size(), equalTo(2));

        logger.info("--> explicitly allocate shard 1, *under dry_run*");
        state = client().admin().cluster().prepareReroute()
                .setExplain(randomBoolean())
                .add(new AllocateEmptyPrimaryAllocationCommand("test", 0, node_1, true))
                .setDryRun(true)
                .execute().actionGet().getState();
        assertThat(state.getRoutingNodes().unassigned().size(), equalTo(1));
        assertThat(state.getRoutingNodes().node(state.nodes().resolveNode(node_1).getId()).iterator().next().state(), equalTo(ShardRoutingState.INITIALIZING));

        logger.info("--> get the state, verify nothing changed because of the dry run");
        state = client().admin().cluster().prepareState().execute().actionGet().getState();
        assertThat(state.getRoutingNodes().unassigned().size(), equalTo(2));

        logger.info("--> explicitly allocate shard 1, actually allocating, no dry run");
        state = client().admin().cluster().prepareReroute()
                .setExplain(randomBoolean())
                .add(new AllocateEmptyPrimaryAllocationCommand("test", 0, node_1, true))
                .execute().actionGet().getState();
        assertThat(state.getRoutingNodes().unassigned().size(), equalTo(1));
        assertThat(state.getRoutingNodes().node(state.nodes().resolveNode(node_1).getId()).iterator().next().state(), equalTo(ShardRoutingState.INITIALIZING));

        ClusterHealthResponse healthResponse = client().admin().cluster().prepareHealth().setWaitForEvents(Priority.LANGUID).setWaitForYellowStatus().execute().actionGet();
        assertThat(healthResponse.isTimedOut(), equalTo(false));

        logger.info("--> get the state, verify shard 1 primary allocated");
        state = client().admin().cluster().prepareState().execute().actionGet().getState();
        assertThat(state.getRoutingNodes().unassigned().size(), equalTo(1));
        assertThat(state.getRoutingNodes().node(state.nodes().resolveNode(node_1).getId()).iterator().next().state(), equalTo(ShardRoutingState.STARTED));

        logger.info("--> move shard 1 primary from node1 to node2");
        state = client().admin().cluster().prepareReroute()
                .setExplain(randomBoolean())
                .add(new MoveAllocationCommand("test", 0, node_1, node_2))
                .execute().actionGet().getState();

        assertThat(state.getRoutingNodes().node(state.nodes().resolveNode(node_1).getId()).iterator().next().state(), equalTo(ShardRoutingState.RELOCATING));
        assertThat(state.getRoutingNodes().node(state.nodes().resolveNode(node_2).getId()).iterator().next().state(), equalTo(ShardRoutingState.INITIALIZING));


        healthResponse = client().admin().cluster().prepareHealth().setWaitForEvents(Priority.LANGUID).setWaitForYellowStatus().setWaitForNoRelocatingShards(true).execute().actionGet();
        assertThat(healthResponse.isTimedOut(), equalTo(false));

        logger.info("--> get the state, verify shard 1 primary moved from node1 to node2");
        state = client().admin().cluster().prepareState().execute().actionGet().getState();
        assertThat(state.getRoutingNodes().unassigned().size(), equalTo(1));
        assertThat(state.getRoutingNodes().node(state.nodes().resolveNode(node_2).getId()).iterator().next().state(), equalTo(ShardRoutingState.STARTED));
    }

    public void testRerouteWithAllocateLocalGateway_disableAllocationSettings() throws Exception {
        Settings commonSettings = Settings.builder()
                .put(EnableAllocationDecider.CLUSTER_ROUTING_ALLOCATION_ENABLE_SETTING.getKey(), "none")
                .put(EnableAllocationDecider.CLUSTER_ROUTING_REBALANCE_ENABLE_SETTING.getKey(), "none")
                .build();
        rerouteWithAllocateLocalGateway(commonSettings);
    }

    public void testRerouteWithAllocateLocalGateway_enableAllocationSettings() throws Exception {
        Settings commonSettings = Settings.builder()
                .put(CLUSTER_ROUTING_ALLOCATION_ENABLE_SETTING.getKey(), Allocation.NONE.name())
                .build();
        rerouteWithAllocateLocalGateway(commonSettings);
    }

    public void testDelayWithALargeAmountOfShards() throws Exception {
        Settings commonSettings = Settings.builder()
                .put(ThrottlingAllocationDecider.CLUSTER_ROUTING_ALLOCATION_NODE_CONCURRENT_INCOMING_RECOVERIES_SETTING.getKey(), 1)
                .put(ThrottlingAllocationDecider.CLUSTER_ROUTING_ALLOCATION_NODE_CONCURRENT_OUTGOING_RECOVERIES_SETTING.getKey(), 1)
                .build();
        logger.info("--> starting 4 nodes");
        String node_1 = internalCluster().startNode(commonSettings);
        internalCluster().startNode(commonSettings);
        internalCluster().startNode(commonSettings);
        internalCluster().startNode(commonSettings);

        assertThat(cluster().size(), equalTo(4));
        ClusterHealthResponse healthResponse = client().admin().cluster().prepareHealth().setWaitForNodes("4").execute().actionGet();
        assertThat(healthResponse.isTimedOut(), equalTo(false));

        logger.info("--> create indices");
        for (int i = 0; i < 25; i++) {
            client().admin().indices().prepareCreate("test" + i)
                    .setSettings(Settings.builder()
                            .put("index.number_of_shards", 5).put("index.number_of_replicas", 1)
                            .put("index.unassigned.node_left.delayed_timeout", randomIntBetween(250, 1000) + "ms"))
                    .execute().actionGet();
        }

        ensureGreen(TimeValue.timeValueMinutes(1));

        logger.info("--> stopping node1");
        internalCluster().stopRandomNode(InternalTestCluster.nameFilter(node_1));

        // This might run slowly on older hardware
        ensureGreen(TimeValue.timeValueMinutes(2));
    }

    private void rerouteWithAllocateLocalGateway(Settings commonSettings) throws Exception {
        logger.info("--> starting 2 nodes");
        String node_1 = internalCluster().startNode(commonSettings);
        internalCluster().startNode(commonSettings);
        assertThat(cluster().size(), equalTo(2));
        ClusterHealthResponse healthResponse = client().admin().cluster().prepareHealth().setWaitForNodes("2").execute().actionGet();
        assertThat(healthResponse.isTimedOut(), equalTo(false));

        logger.info("--> create an index with 1 shard, 1 replica, nothing should allocate");
        client().admin().indices().prepareCreate("test").setWaitForActiveShards(ActiveShardCount.NONE)
                .setSettings(Settings.builder().put("index.number_of_shards", 1))
                .execute().actionGet();

        ClusterState state = client().admin().cluster().prepareState().execute().actionGet().getState();
        assertThat(state.getRoutingNodes().unassigned().size(), equalTo(2));

        logger.info("--> explicitly allocate shard 1, actually allocating, no dry run");
        state = client().admin().cluster().prepareReroute()
                .setExplain(randomBoolean())
                .add(new AllocateEmptyPrimaryAllocationCommand("test", 0, node_1, true))
                .execute().actionGet().getState();
        assertThat(state.getRoutingNodes().unassigned().size(), equalTo(1));
        assertThat(state.getRoutingNodes().node(state.nodes().resolveNode(node_1).getId()).iterator().next().state(), equalTo(ShardRoutingState.INITIALIZING));

        healthResponse = client().admin().cluster().prepareHealth().setWaitForEvents(Priority.LANGUID).setWaitForYellowStatus().execute().actionGet();
        assertThat(healthResponse.isTimedOut(), equalTo(false));

        logger.info("--> get the state, verify shard 1 primary allocated");
        state = client().admin().cluster().prepareState().execute().actionGet().getState();
        assertThat(state.getRoutingNodes().unassigned().size(), equalTo(1));
        assertThat(state.getRoutingNodes().node(state.nodes().resolveNode(node_1).getId()).iterator().next().state(), equalTo(ShardRoutingState.STARTED));

        client().prepareIndex("test", "type", "1").setSource("field", "value").setRefreshPolicy(RefreshPolicy.IMMEDIATE).get();
        final Index index = resolveIndex("test");

        logger.info("--> closing all nodes");
        Path[] shardLocation = internalCluster().getInstance(NodeEnvironment.class, node_1).availableShardPaths(new ShardId(index, 0));
        assertThat(FileSystemUtils.exists(shardLocation), equalTo(true)); // make sure the data is there!
        internalCluster().closeNonSharedNodes(false); // don't wipe data directories the index needs to be there!

        logger.info("--> deleting the shard data [{}] ", Arrays.toString(shardLocation));
        assertThat(FileSystemUtils.exists(shardLocation), equalTo(true)); // verify again after cluster was shut down
        IOUtils.rm(shardLocation);

        logger.info("--> starting nodes back, will not allocate the shard since it has no data, but the index will be there");
        node_1 = internalCluster().startNode(commonSettings);
        internalCluster().startNode(commonSettings);
        // wait a bit for the cluster to realize that the shard is not there...
        // TODO can we get around this? the cluster is RED, so what do we wait for?
        client().admin().cluster().prepareReroute().get();
        assertThat(client().admin().cluster().prepareHealth().setWaitForNodes("2").execute().actionGet().getStatus(), equalTo(ClusterHealthStatus.RED));
        logger.info("--> explicitly allocate primary");
        state = client().admin().cluster().prepareReroute()
                .setExplain(randomBoolean())
                .add(new AllocateEmptyPrimaryAllocationCommand("test", 0, node_1, true))
                .execute().actionGet().getState();
        assertThat(state.getRoutingNodes().unassigned().size(), equalTo(1));
        assertThat(state.getRoutingNodes().node(state.nodes().resolveNode(node_1).getId()).iterator().next().state(), equalTo(ShardRoutingState.INITIALIZING));

        logger.info("--> get the state, verify shard 1 primary allocated");
        final String nodeToCheck = node_1;
        assertBusy(() -> {
            ClusterState clusterState = client().admin().cluster().prepareState().execute().actionGet().getState();
            String nodeId = clusterState.nodes().resolveNode(nodeToCheck).getId();
            assertThat(clusterState.getRoutingNodes().node(nodeId).iterator().next().state(), equalTo(ShardRoutingState.STARTED));
        });
    }

    public void testRerouteExplain() {
        Settings commonSettings = Settings.builder().build();

        logger.info("--> starting a node");
        String node_1 = internalCluster().startNode(commonSettings);

        assertThat(cluster().size(), equalTo(1));
        ClusterHealthResponse healthResponse = client().admin().cluster().prepareHealth().setWaitForNodes("1").execute().actionGet();
        assertThat(healthResponse.isTimedOut(), equalTo(false));

        logger.info("--> create an index with 1 shard");
        client().admin().indices().prepareCreate("test")
                .setSettings(Settings.builder().put("index.number_of_shards", 1).put("index.number_of_replicas", 0))
                .execute().actionGet();

        ensureGreen("test");

        logger.info("--> disable allocation");
        Settings newSettings = Settings.builder()
                .put(CLUSTER_ROUTING_ALLOCATION_ENABLE_SETTING.getKey(), Allocation.NONE.name())
                .build();
        client().admin().cluster().prepareUpdateSettings().setTransientSettings(newSettings).execute().actionGet();

        logger.info("--> starting a second node");
        String node_2 = internalCluster().startNode(commonSettings);
        assertThat(cluster().size(), equalTo(2));
        healthResponse = client().admin().cluster().prepareHealth().setWaitForNodes("2").execute().actionGet();
        assertThat(healthResponse.isTimedOut(), equalTo(false));

        logger.info("--> try to move the shard from node1 to node2");
        MoveAllocationCommand cmd = new MoveAllocationCommand("test", 0, node_1, node_2);
        ClusterRerouteResponse resp = client().admin().cluster().prepareReroute().add(cmd).setExplain(true).execute().actionGet();
        RoutingExplanations e = resp.getExplanations();
        assertThat(e.explanations().size(), equalTo(1));
        RerouteExplanation explanation = e.explanations().get(0);
        assertThat(explanation.command().name(), equalTo(cmd.name()));
        assertThat(((MoveAllocationCommand)explanation.command()).shardId(), equalTo(cmd.shardId()));
        assertThat(((MoveAllocationCommand)explanation.command()).fromNode(), equalTo(cmd.fromNode()));
        assertThat(((MoveAllocationCommand)explanation.command()).toNode(), equalTo(cmd.toNode()));
        assertThat(explanation.decisions().type(), equalTo(Decision.Type.YES));
    }

    public void testClusterRerouteWithBlocks() throws Exception {
        List<String> nodesIds = internalCluster().startNodes(2);

        logger.info("--> create an index with 1 shard and 0 replicas");
        assertAcked(prepareCreate("test-blocks").setSettings(Settings.builder().put("index.number_of_shards", 1).put("index.number_of_replicas", 0)));
        ensureGreen("test-blocks");

        logger.info("--> check that the index has 1 shard");
        ClusterState state = client().admin().cluster().prepareState().execute().actionGet().getState();
        List<ShardRouting> shards = state.routingTable().allShards("test-blocks");
        assertThat(shards, hasSize(1));

        logger.info("--> check that the shard is allocated");
        ShardRouting shard = shards.get(0);
        assertThat(shard.assignedToNode(), equalTo(true));

        logger.info("--> retrieve the node where the shard is allocated");
        DiscoveryNode node = state.nodes().resolveNode(shard.currentNodeId());
        assertNotNull(node);

        // toggle is used to mve the shard from one node to another
        int toggle = nodesIds.indexOf(node.getName());

        // Rerouting shards is not blocked
        for (String blockSetting : Arrays.asList(SETTING_BLOCKS_READ, SETTING_BLOCKS_WRITE, SETTING_READ_ONLY, SETTING_BLOCKS_METADATA)) {
            try {
                enableIndexBlock("test-blocks", blockSetting);
                assertAcked(client().admin().cluster().prepareReroute()
                        .add(new MoveAllocationCommand("test-blocks", 0, nodesIds.get(toggle % 2), nodesIds.get(++toggle % 2))));

                ClusterHealthResponse healthResponse = client().admin().cluster().prepareHealth().setWaitForYellowStatus().setWaitForNoRelocatingShards(true).execute().actionGet();
                assertThat(healthResponse.isTimedOut(), equalTo(false));
            } finally {
                disableIndexBlock("test-blocks", blockSetting);
            }
        }

        // Rerouting shards is blocked when the cluster is read only
        try {
            setClusterReadOnly(true);
            assertBlocked(client().admin().cluster().prepareReroute()
                    .add(new MoveAllocationCommand("test-blocks", 1, nodesIds.get(toggle % 2), nodesIds.get(++toggle % 2))));
        } finally {
            setClusterReadOnly(false);
        }
    }
}
