Default max local storage nodes to one

This commit defaults the max local storage nodes to one. The motivation
for this change is that a default value greather than one is dangerous
as users sometimes end up unknowingly starting a second node and start
thinking that they have encountered data loss.

Relates #19964

buildSrc/src/main/groovy/org/elasticsearch/gradle/test/ClusterFormationTasks.groovy

@@ -261,6 +261,7 @@ class ClusterFormationTasks {
                 'node.attr.testattr'                : 'test',
                 'repositories.url.allowed_urls': 'http://snapshot.test*'
         ]
+        esConfig['node.max_local_storage_nodes'] = node.config.numNodes
         esConfig['http.port'] = node.config.httpPort
         esConfig['transport.tcp.port'] =  node.config.transportPort
         esConfig.putAll(node.config.settings)

core/src/main/java/org/elasticsearch/env/NodeEnvironment.java

@@ -68,6 +68,7 @@ import java.util.Collection;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.Random;
 import java.util.Set;
@@ -151,7 +152,7 @@ public final class NodeEnvironment  implements Closeable {
     /**
      * Maximum number of data nodes that should run in an environment.
      */
-    public static final Setting<Integer> MAX_LOCAL_STORAGE_NODES_SETTING = Setting.intSetting("node.max_local_storage_nodes", 50, 1,
+    public static final Setting<Integer> MAX_LOCAL_STORAGE_NODES_SETTING = Setting.intSetting("node.max_local_storage_nodes", 1, 1,
         Property.NodeScope);
 
     /**
@@ -244,8 +245,15 @@ public final class NodeEnvironment  implements Closeable {
             }
 
             if (locks[0] == null) {
-                throw new IllegalStateException("Failed to obtain node lock, is the following location writable?: "
-                    + Arrays.toString(environment.dataWithClusterFiles()), lastException);
+                final String message = String.format(
+                    Locale.ROOT,
+                    "failed to obtain node locks, tried [%s] with lock id%s;" +
+                        " maybe these locations are not writable or multiple nodes were started without increasing [%s] (was [%d])?",
+                    Arrays.toString(environment.dataWithClusterFiles()),
+                    maxLocalStorageNodes == 1 ? " [0]" : "s [0--" + (maxLocalStorageNodes - 1) + "]",
+                    MAX_LOCAL_STORAGE_NODES_SETTING.getKey(),
+                    maxLocalStorageNodes);
+                throw new IllegalStateException(message, lastException);
             }
             this.nodeMetaData = loadOrCreateNodeMetaData(settings, startupTraceLogger, nodePaths);
             this.logger = Loggers.getLogger(getClass(), Node.addNodeNameIfNeeded(settings, this.nodeMetaData.nodeId()));

core/src/main/java/org/elasticsearch/tribe/TribeService.java

@@ -117,6 +117,9 @@ public class TribeService extends AbstractLifecycleComponent {
         sb.put(Node.NODE_MASTER_SETTING.getKey(), false);
         sb.put(Node.NODE_DATA_SETTING.getKey(), false);
         sb.put(Node.NODE_INGEST_SETTING.getKey(), false);
+        if (!NodeEnvironment.MAX_LOCAL_STORAGE_NODES_SETTING.exists(settings)) {
+            sb.put(NodeEnvironment.MAX_LOCAL_STORAGE_NODES_SETTING.getKey(), nodesSettings.size());
+        }
         sb.put(DiscoveryModule.DISCOVERY_TYPE_SETTING.getKey(), "local"); // a tribe node should not use zen discovery
         // nothing is going to be discovered, since no master will be elected
         sb.put(DiscoverySettings.INITIAL_STATE_TIMEOUT_SETTING.getKey(), 0);

core/src/test/java/org/elasticsearch/cluster/ClusterInfoServiceIT.java

@@ -38,6 +38,7 @@ import org.elasticsearch.common.collect.ImmutableOpenMap;
 import org.elasticsearch.common.inject.Inject;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.unit.TimeValue;
+import org.elasticsearch.env.NodeEnvironment;
 import org.elasticsearch.index.IndexService;
 import org.elasticsearch.index.shard.IndexShard;
 import org.elasticsearch.index.store.Store;
@@ -118,6 +119,7 @@ public class ClusterInfoServiceIT extends ESIntegTestCase {
     protected Settings nodeSettings(int nodeOrdinal) {
         return Settings.builder()
                 // manual collection or upon cluster forming.
+                .put(NodeEnvironment.MAX_LOCAL_STORAGE_NODES_SETTING.getKey(), 2)
                 .put(InternalClusterInfoService.INTERNAL_CLUSTER_INFO_TIMEOUT_SETTING.getKey(), "1s")
                 .build();
     }

core/src/test/java/org/elasticsearch/discovery/DiscoveryWithServiceDisruptionsIT.java

@@ -55,6 +55,7 @@ import org.elasticsearch.discovery.zen.ping.ZenPing;
 import org.elasticsearch.discovery.zen.ping.ZenPingService;
 import org.elasticsearch.discovery.zen.ping.unicast.UnicastZenPing;
 import org.elasticsearch.discovery.zen.publish.PublishClusterStateAction;
+import org.elasticsearch.env.NodeEnvironment;
 import org.elasticsearch.indices.store.IndicesStoreIntegrationIT;
 import org.elasticsearch.plugins.Plugin;
 import org.elasticsearch.test.ESIntegTestCase;
@@ -207,6 +208,7 @@ public class DiscoveryWithServiceDisruptionsIT extends ESIntegTestCase {
         // TODO: Rarely use default settings form some of these
         Settings nodeSettings = Settings.builder()
                 .put(settings)
+                .put(NodeEnvironment.MAX_LOCAL_STORAGE_NODES_SETTING.getKey(), 4)
                 .put(ElectMasterService.DISCOVERY_ZEN_MINIMUM_MASTER_NODES_SETTING.getKey(), minimumMasterNode)
                 .build();
 

core/src/test/java/org/elasticsearch/env/NodeEnvironmentTests.java

@@ -74,18 +74,14 @@ public class NodeEnvironmentTests extends ESTestCase {
     }
 
     public void testNodeLockSingleEnvironment() throws IOException {
-        final Settings settings = buildEnvSettings(Settings.builder()
-            .put(NodeEnvironment.MAX_LOCAL_STORAGE_NODES_SETTING.getKey(), 1).build());
+        final Settings settings = buildEnvSettings(Settings.builder().put("node.max_local_storage_nodes", 1).build());
         NodeEnvironment env = newNodeEnvironment(settings);
         List<String> dataPaths = Environment.PATH_DATA_SETTING.get(settings);
 
-        try {
-            // Reuse the same location and attempt to lock again
-            new NodeEnvironment(settings, new Environment(settings));
-            fail("env has already locked all the data directories it is allowed");
-        } catch (IllegalStateException ex) {
-            assertThat(ex.getMessage(), containsString("Failed to obtain node lock"));
-        }
+        // Reuse the same location and attempt to lock again
+        IllegalStateException ex =
+            expectThrows(IllegalStateException.class, () -> new NodeEnvironment(settings, new Environment(settings)));
+        assertThat(ex.getMessage(), containsString("failed to obtain node lock"));
 
         // Close the environment that holds the lock and make sure we can get the lock after release
         env.close();
@@ -121,7 +117,7 @@ public class NodeEnvironmentTests extends ESTestCase {
     }
 
     public void testNodeLockMultipleEnvironment() throws IOException {
-        final Settings settings = buildEnvSettings(Settings.EMPTY);
+        final Settings settings = buildEnvSettings(Settings.builder().put("node.max_local_storage_nodes", 2).build());
         final NodeEnvironment first = newNodeEnvironment(settings);
         List<String> dataPaths = Environment.PATH_DATA_SETTING.get(settings);
         NodeEnvironment second = new NodeEnvironment(settings, new Environment(settings));

core/src/test/java/org/elasticsearch/indices/memory/breaker/CircuitBreakerNoopIT.java

@@ -22,6 +22,7 @@ package org.elasticsearch.indices.memory.breaker;
 import org.elasticsearch.action.index.IndexRequestBuilder;
 import org.elasticsearch.client.Client;
 import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.env.NodeEnvironment;
 import org.elasticsearch.indices.breaker.HierarchyCircuitBreakerService;
 import org.elasticsearch.search.sort.SortOrder;
 import org.elasticsearch.test.ESIntegTestCase;
@@ -40,6 +41,7 @@ public class CircuitBreakerNoopIT extends ESIntegTestCase {
     @Override
     protected Settings nodeSettings(int nodeOrdinal) {
         return Settings.builder()
+                .put(NodeEnvironment.MAX_LOCAL_STORAGE_NODES_SETTING.getKey(), 2)
                 .put(HierarchyCircuitBreakerService.FIELDDATA_CIRCUIT_BREAKER_TYPE_SETTING.getKey(), "noop")
                 // This is set low, because if the "noop" is not a noop, it will break
                 .put(HierarchyCircuitBreakerService.FIELDDATA_CIRCUIT_BREAKER_LIMIT_SETTING.getKey(), "10b")

core/src/test/java/org/elasticsearch/tribe/TribeIT.java

@@ -39,6 +39,7 @@ import org.elasticsearch.common.transport.TransportAddress;
 import org.elasticsearch.discovery.DiscoveryModule;
 import org.elasticsearch.discovery.MasterNotDiscoveredException;
 import org.elasticsearch.discovery.zen.ping.unicast.UnicastZenPing;
+import org.elasticsearch.env.NodeEnvironment;
 import org.elasticsearch.node.Node;
 import org.elasticsearch.test.ESIntegTestCase;
 import org.elasticsearch.test.InternalTestCluster;
@@ -128,6 +129,7 @@ public class TribeIT extends ESIntegTestCase {
         tribe1Defaults.putArray("tribe.t2." + UnicastZenPing.DISCOVERY_ZEN_PING_UNICAST_HOSTS_SETTING.getKey(), getUnicastHosts(cluster2.client()));
 
         Settings merged = Settings.builder()
+                .put(internalCluster().getDefaultSettings())
                 .put("tribe.t1.cluster.name", internalCluster().getClusterName())
                 .put("tribe.t2.cluster.name", cluster2.getClusterName())
                 .put("tribe.t1.transport.type", "local")
@@ -142,7 +144,6 @@ public class TribeIT extends ESIntegTestCase {
 
                 .put(tribe1Defaults.build())
                 .put(tribe2Defaults.build())
-                .put(internalCluster().getDefaultSettings())
                 .put("node.name", "tribe_node") // make sure we can identify threads from this node
                 .build();
 

docs/reference/migration/migrate_5_0/settings.asciidoc

@@ -310,3 +310,14 @@ The unit 'w' representing weeks is no longer supported.
 
 Fractional time values (e.g., 0.5s) are no longer supported. For example, this means when setting
 timeouts "0.5s" will be rejected and should instead be input as "500ms".
+
+==== Node max local storage nodes
+
+Previous versions of Elasticsearch defaulted to allowing multiple nodes to share the same data
+directory (up to 50). This can be confusing where users accidentally startup multiple nodes and end
+up thinking that they've lost data because the second node will start with an empty data directory.
+While the default of allowing multiple nodes is friendly to playing with forming a small cluster on
+a laptop, and end-users do sometimes run multiple nodes on the same host, this tends to be the
+exception. Keeping with Elasticsearch's continual movement towards safer out-of-the-box defaults,
+and optimizing for the norm instead of the exception, the default for
+`node.max_local_storage_nodes` is now one.

qa/evil-tests/src/test/java/org/elasticsearch/tribe/TribeUnitTests.java

@@ -60,7 +60,9 @@ public class TribeUnitTests extends ESTestCase {
             .put(NetworkModule.HTTP_ENABLED.getKey(), false)
             .put("transport.type", "local")
             .put(DiscoveryModule.DISCOVERY_TYPE_SETTING.getKey(), "local")
-            .put(Environment.PATH_HOME_SETTING.getKey(), createTempDir()).build();
+            .put(Environment.PATH_HOME_SETTING.getKey(), createTempDir())
+            .put(NodeEnvironment.MAX_LOCAL_STORAGE_NODES_SETTING.getKey(), 2)
+            .build();
 
         tribe1 = new TribeClientNode(
             Settings.builder()

test/framework/src/main/java/org/elasticsearch/test/ESIntegTestCase.java

@@ -31,6 +31,7 @@ import org.elasticsearch.ExceptionsHelper;
 import org.elasticsearch.action.DocWriteResponse;
 import org.elasticsearch.discovery.DiscoveryModule;
 import org.elasticsearch.client.RestClientBuilder;
+import org.elasticsearch.env.NodeEnvironment;
 import org.elasticsearch.script.ScriptService;
 import org.elasticsearch.transport.MockTcpTransportPlugin;
 import org.elasticsearch.action.ActionListener;
@@ -1630,6 +1631,7 @@ public abstract class ESIntegTestCase extends ESTestCase {
      */
     protected Settings nodeSettings(int nodeOrdinal) {
         Settings.Builder builder = Settings.builder()
+                .put(NodeEnvironment.MAX_LOCAL_STORAGE_NODES_SETTING.getKey(), Integer.MAX_VALUE)
                 // Default the watermarks to absurdly low to prevent the tests
                 // from failing on nodes without enough disk space
                 .put(DiskThresholdDecider.CLUSTER_ROUTING_ALLOCATION_LOW_DISK_WATERMARK_SETTING.getKey(), "1b")

test/framework/src/main/java/org/elasticsearch/test/InternalTestCluster.java

@@ -175,8 +175,8 @@ public final class InternalTestCluster extends TestCluster {
     public final int HTTP_BASE_PORT = GLOBAL_HTTP_BASE_PORT + CLUSTER_BASE_PORT_OFFSET;
 
 
-    static final int DEFAULT_LOW_NUM_MASTER_NODES = 1;
-    static final int DEFAULT_HIGH_NUM_MASTER_NODES = 3;
+    public static final int DEFAULT_LOW_NUM_MASTER_NODES = 1;
+    public static final int DEFAULT_HIGH_NUM_MASTER_NODES = 3;
 
     static final int DEFAULT_MIN_NUM_DATA_NODES = 1;
     static final int DEFAULT_MAX_NUM_DATA_NODES = TEST_NIGHTLY ? 6 : 3;
@@ -300,6 +300,7 @@ public final class InternalTestCluster extends TestCluster {
                 builder.put(Environment.PATH_DATA_SETTING.getKey(), dataPath.toString());
             }
         }
+        builder.put(NodeEnvironment.MAX_LOCAL_STORAGE_NODES_SETTING.getKey(), Integer.MAX_VALUE);
         builder.put(Environment.PATH_SHARED_DATA_SETTING.getKey(), baseDir.resolve("custom"));
         builder.put(Environment.PATH_HOME_SETTING.getKey(), baseDir);
         builder.put(Environment.PATH_REPO_SETTING.getKey(), baseDir.resolve("repos"));

test/framework/src/main/java/org/elasticsearch/test/discovery/ClusterDiscoveryConfiguration.java

@@ -26,6 +26,7 @@ import org.elasticsearch.common.network.NetworkUtils;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.util.CollectionUtils;
 import org.elasticsearch.discovery.DiscoveryModule;
+import org.elasticsearch.env.NodeEnvironment;
 import org.elasticsearch.test.InternalTestCluster;
 import org.elasticsearch.test.NodeConfigurationSource;
 import org.elasticsearch.transport.TransportSettings;
@@ -108,7 +109,7 @@ public class ClusterDiscoveryConfiguration extends NodeConfigurationSource {
 
         @Override
         public Settings nodeSettings(int nodeOrdinal) {
-            Settings.Builder builder = Settings.builder();
+            Settings.Builder builder = Settings.builder().put(NodeEnvironment.MAX_LOCAL_STORAGE_NODES_SETTING.getKey(), numOfNodes);
 
             String[] unicastHosts = new String[unicastHostOrdinals.length];
             if (nodeOrdinal >= unicastHostPorts.length) {

test/framework/src/test/java/org/elasticsearch/test/test/InternalTestClusterTests.java

@@ -128,12 +128,16 @@ public class InternalTestClusterTests extends ESTestCase {
         boolean masterNodes = randomBoolean();
         int minNumDataNodes = randomIntBetween(0, 3);
         int maxNumDataNodes = randomIntBetween(minNumDataNodes, 4);
+        int numClientNodes = randomIntBetween(0, 2);
         final String clusterName1 = "shared1";
         final String clusterName2 = "shared2";
         NodeConfigurationSource nodeConfigurationSource = new NodeConfigurationSource() {
             @Override
             public Settings nodeSettings(int nodeOrdinal) {
                 return Settings.builder()
+                    .put(
+                        NodeEnvironment.MAX_LOCAL_STORAGE_NODES_SETTING.getKey(),
+                        2 * ((masterNodes ? InternalTestCluster.DEFAULT_HIGH_NUM_MASTER_NODES : 0) + maxNumDataNodes + numClientNodes))
                     .put(NetworkModule.HTTP_ENABLED.getKey(), false)
                     .put(DiscoveryModule.DISCOVERY_TYPE_SETTING.getKey(), "local")
                     .put(NetworkModule.TRANSPORT_TYPE_KEY, "local").build();
@@ -145,7 +149,7 @@ public class InternalTestClusterTests extends ESTestCase {
                     .put(NetworkModule.TRANSPORT_TYPE_KEY, "local").build();
             }
         };
-        int numClientNodes = randomIntBetween(0, 2);
+
         boolean enableHttpPipelining = randomBoolean();
         String nodePrefix = "foobar";
 
@@ -187,13 +191,17 @@ public class InternalTestClusterTests extends ESTestCase {
         long clusterSeed = randomLong();
         boolean masterNodes = randomBoolean();
         // we need one stable node
-        int minNumDataNodes = 2;
-        int maxNumDataNodes = 2;
+        final int minNumDataNodes = 2;
+        final int maxNumDataNodes = 2;
+        final int numClientNodes = randomIntBetween(0, 2);
         final String clusterName1 = "shared1";
         NodeConfigurationSource nodeConfigurationSource = new NodeConfigurationSource() {
             @Override
             public Settings nodeSettings(int nodeOrdinal) {
                 return Settings.builder().put(NetworkModule.HTTP_ENABLED.getKey(), false)
+                    .put(
+                        NodeEnvironment.MAX_LOCAL_STORAGE_NODES_SETTING.getKey(),
+                        2 + (masterNodes ? InternalTestCluster.DEFAULT_HIGH_NUM_MASTER_NODES : 0) + maxNumDataNodes + numClientNodes)
                     .put(NetworkModule.TRANSPORT_TYPE_KEY, "local")
                     .put(DiscoveryModule.DISCOVERY_TYPE_SETTING.getKey(), "local")
                     .build();
@@ -203,7 +211,7 @@ public class InternalTestClusterTests extends ESTestCase {
                 return Settings.builder()
                     .put(NetworkModule.TRANSPORT_TYPE_KEY, "local").build();
             }
-        };        int numClientNodes = randomIntBetween(0, 2);
+        };
         boolean enableHttpPipelining = randomBoolean();
         String nodePrefix = "test";
         Path baseDir = createTempDir();
@@ -269,11 +277,13 @@ public class InternalTestClusterTests extends ESTestCase {
 
     public void testDifferentRolesMaintainPathOnRestart() throws Exception {
         final Path baseDir = createTempDir();
+        final int numNodes = 5;
         InternalTestCluster cluster = new InternalTestCluster(randomLong(), baseDir, true, 0, 0, "test",
             new NodeConfigurationSource() {
                 @Override
                 public Settings nodeSettings(int nodeOrdinal) {
                     return Settings.builder()
+                        .put(NodeEnvironment.MAX_LOCAL_STORAGE_NODES_SETTING.getKey(), numNodes)
                         .put(NetworkModule.HTTP_ENABLED.getKey(), false)
                         .put(NetworkModule.TRANSPORT_TYPE_KEY, "local")
                         .put(DiscoveryModule.DISCOVERY_TYPE_SETTING.getKey(), "local")
@@ -289,7 +299,7 @@ public class InternalTestClusterTests extends ESTestCase {
         cluster.beforeTest(random(), 0.0);
         try {
             Map<DiscoveryNode.Role, Set<String>> pathsPerRole = new HashMap<>();
-            for (int i = 0; i < 5; i++) {
+            for (int i = 0; i < numNodes; i++) {
                 final DiscoveryNode.Role role = randomFrom(MASTER, DiscoveryNode.Role.DATA, DiscoveryNode.Role.INGEST);
                 final String node;
                 switch (role) {