Deprecate minimum_master_nodes (#37868)

Today we pass `discovery.zen.minimum_master_nodes` to nodes started up in
tests, but for 7.x nodes this setting is not required as it has no effect.
This commit removes this setting so that nodes are started with more realistic
configurations, and deprecates it.

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

@@ -373,18 +373,15 @@ class ClusterFormationTasks {
                 'path.repo'                    : "${node.sharedDir}/repo",
                 'path.shared_data'             : "${node.sharedDir}/",
                 // Define a node attribute so we can test that it exists
-                'node.attr.testattr'           : 'test'
+                'node.attr.testattr'           : 'test',
+                // Don't wait for state, just start up quickly. This will also allow new and old nodes in the BWC case to become the master
+                'discovery.initial_state_timeout' : '0s'
         ]
         int minimumMasterNodes = node.config.minimumMasterNodes.call()
-        if (minimumMasterNodes > 0) {
+        if (node.nodeVersion.before("7.0.0") && minimumMasterNodes > 0) {
             esConfig['discovery.zen.minimum_master_nodes'] = minimumMasterNodes
         }
-        if (minimumMasterNodes > 1) {
-            // don't wait for state.. just start up quickly
-            // this will also allow new and old nodes in the BWC case to become the master
-            esConfig['discovery.initial_state_timeout'] = '0s'
-        }
-        if (esConfig.containsKey('discovery.zen.master_election.wait_for_joins_timeout') == false) {
+        if (node.nodeVersion.before("7.0.0") && esConfig.containsKey('discovery.zen.master_election.wait_for_joins_timeout') == false) {
             // If a node decides to become master based on partial information from the pinging, don't let it hang for 30 seconds to correct
             // its mistake. Instead, only wait 5s to do another round of pinging.
             // This is necessary since we use 30s as the default timeout in REST requests waiting for cluster formation

docs/reference/migration/migrate_7_0/discovery.asciidoc

@@ -13,8 +13,8 @@ settings summary>> for an example, and the
 <<modules-discovery-bootstrap-cluster,cluster bootstrapping reference
 documentation>> describes this setting in more detail.
 
-The `discovery.zen.minimum_master_nodes` setting is required during a rolling
-upgrade from 6.x, but can be removed in all other circumstances.
+The `discovery.zen.minimum_master_nodes` setting is permitted, but ignored, on
+7.x nodes.
 
 [float]
 ==== Removing master-eligible nodes sometimes requires voting exclusions

modules/transport-netty4/src/test/java/org/elasticsearch/rest/discovery/Zen2RestApiIT.java

@@ -33,9 +33,7 @@
 import org.elasticsearch.cluster.routing.UnassignedInfo;
 import org.elasticsearch.common.Priority;
 import org.elasticsearch.common.settings.Settings;
-import org.elasticsearch.common.settings.Settings.Builder;
 import org.elasticsearch.common.unit.TimeValue;
-import org.elasticsearch.discovery.zen.ElectMasterService;
 import org.elasticsearch.http.HttpServerTransport;
 import org.elasticsearch.test.ESIntegTestCase;
 import org.elasticsearch.test.InternalTestCluster;
@@ -58,11 +56,7 @@ public class Zen2RestApiIT extends ESNetty4IntegTestCase {
 
     @Override
     protected Settings nodeSettings(int nodeOrdinal) {
-        final Builder builder = Settings.builder().put(super.nodeSettings(nodeOrdinal))
-            .put(TestZenDiscovery.USE_ZEN2.getKey(), true)
-            .put(ElectMasterService.DISCOVERY_ZEN_MINIMUM_MASTER_NODES_SETTING.getKey(), Integer.MAX_VALUE);
-
-        return builder.build();
+        return Settings.builder().put(super.nodeSettings(nodeOrdinal)).put(TestZenDiscovery.USE_ZEN2.getKey(), true).build();
     }
 
     @Override

plugins/discovery-ec2/src/test/java/org/elasticsearch/discovery/ec2/Ec2DiscoveryUpdateSettingsTests.java

@@ -21,6 +21,7 @@
 
 
 import org.elasticsearch.action.admin.cluster.settings.ClusterUpdateSettingsResponse;
+import org.elasticsearch.common.UUIDs;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.discovery.DiscoveryModule;
 import org.elasticsearch.test.ESIntegTestCase.ClusterScope;
@@ -41,13 +42,14 @@ public void testMinimumMasterNodesStart() {
                 .build();
         internalCluster().startNode(nodeSettings);
 
-        // We try to update minimum_master_nodes now
-        ClusterUpdateSettingsResponse response = client().admin().cluster().prepareUpdateSettings()
-                .setPersistentSettings(Settings.builder().put("discovery.zen.minimum_master_nodes", 1))
-                .setTransientSettings(Settings.builder().put("discovery.zen.minimum_master_nodes", 1))
+        // We try to update a setting now
+        final String expectedValue = UUIDs.randomBase64UUID(random());
+        final String settingName = "cluster.routing.allocation.exclude.any_attribute";
+        final ClusterUpdateSettingsResponse response = client().admin().cluster().prepareUpdateSettings()
+                .setPersistentSettings(Settings.builder().put(settingName, expectedValue))
                 .get();
 
-        Integer min = response.getPersistentSettings().getAsInt("discovery.zen.minimum_master_nodes", null);
-        assertThat(min, is(1));
+        final String value = response.getPersistentSettings().get(settingName);
+        assertThat(value, is(expectedValue));
     }
 }

qa/logging-config/src/test/java/org/elasticsearch/qa/custom_logging/CustomLoggingConfigIT.java

@@ -40,7 +40,7 @@
  * The intention is to confirm that users can still run their Elasticsearch instances with previous configurations.
  */
 public class CustomLoggingConfigIT extends ESRestTestCase {
-    private static final String NODE_STARTED = ".*node-0.*cluster.uuid.*node.id.*started.*";
+    private static final String NODE_STARTED = ".*node-0.*cluster.uuid.*node.id.*recovered.*cluster_state.*";
 
     public void testSuccessfulStartupWithCustomConfig() throws Exception {
         assertBusy(() -> {

qa/rolling-upgrade/build.gradle

@@ -77,7 +77,6 @@ for (Version version : bwcVersions.wireCompatible) {
       dependsOn lastRunner, "${baseName}#oldClusterTestCluster#node${stopNode}.stop"
       clusterName = 'rolling-upgrade'
       otherUnicastHostAddresses = { getOtherUnicastHostAddresses() }
-      minimumMasterNodes = { 2 }
       autoSetInitialMasterNodes = false
       /* Override the data directory so the new node always gets the node we
       * just stopped's data directory. */

rest-api-spec/src/main/resources/rest-api-spec/test/cluster.put_settings/10_basic.yml

@@ -4,22 +4,22 @@
       cluster.put_settings:
         body:
           transient:
-            discovery.zen.minimum_master_nodes: 1
+            cluster.routing.allocation.enable: "none"
         flat_settings: true
 
-  - match: {transient: {discovery.zen.minimum_master_nodes: "1"}}
+  - match: {transient: {cluster.routing.allocation.enable: "none"}}
 
   - do:
       cluster.get_settings:
         flat_settings: true
 
-  - match: {transient: {discovery.zen.minimum_master_nodes: "1"}}
+  - match: {transient: {cluster.routing.allocation.enable: "none"}}
 
   - do:
       cluster.put_settings:
         body:
           transient:
-            discovery.zen.minimum_master_nodes: null
+            cluster.routing.allocation.enable: null
         flat_settings: true
 
   - match: {transient: {}}
@@ -35,22 +35,22 @@
       cluster.put_settings:
         body:
           persistent:
-            cluster.routing.allocation.disk.threshold_enabled: false
+            cluster.routing.allocation.enable: "none"
         flat_settings: true
 
-  - match: {persistent: {cluster.routing.allocation.disk.threshold_enabled: "false"}}
+  - match: {persistent: {cluster.routing.allocation.enable: "none"}}
 
   - do:
       cluster.get_settings:
         flat_settings: true
 
-  - match: {persistent: {cluster.routing.allocation.disk.threshold_enabled: "false"}}
+  - match: {persistent: {cluster.routing.allocation.enable: "none"}}
 
   - do:
       cluster.put_settings:
         body:
           persistent:
-            cluster.routing.allocation.disk.threshold_enabled: null
+            cluster.routing.allocation.enable: null
         flat_settings: true
 
   - match: {persistent: {}}

server/src/main/java/org/elasticsearch/discovery/zen/ElectMasterService.java

@@ -42,7 +42,7 @@ public class ElectMasterService {
     private static final Logger logger = LogManager.getLogger(ElectMasterService.class);
 
     public static final Setting<Integer> DISCOVERY_ZEN_MINIMUM_MASTER_NODES_SETTING =
-        Setting.intSetting("discovery.zen.minimum_master_nodes", -1, Property.Dynamic, Property.NodeScope);
+        Setting.intSetting("discovery.zen.minimum_master_nodes", -1, Property.Dynamic, Property.NodeScope, Property.Deprecated);
 
     private volatile int minimumMasterNodes;
 

server/src/test/java/org/elasticsearch/action/admin/indices/exists/IndicesExistsIT.java

@@ -23,7 +23,6 @@
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.unit.TimeValue;
 import org.elasticsearch.discovery.MasterNotDiscoveredException;
-import org.elasticsearch.discovery.zen.ElectMasterService;
 import org.elasticsearch.gateway.GatewayService;
 import org.elasticsearch.test.ESIntegTestCase;
 import org.elasticsearch.test.ESIntegTestCase.ClusterScope;
@@ -51,8 +50,7 @@ protected List<Settings> addExtraClusterBootstrapSettings(List<Settings> allNode
 
     public void testIndexExistsWithBlocksInPlace() throws IOException {
         Settings settings = Settings.builder()
-            .put(GatewayService.RECOVER_AFTER_NODES_SETTING.getKey(), 99)
-            .put(ElectMasterService.DISCOVERY_ZEN_MINIMUM_MASTER_NODES_SETTING.getKey(), Integer.MAX_VALUE).build();
+            .put(GatewayService.RECOVER_AFTER_NODES_SETTING.getKey(), 99).build();
         String node = internalCluster().startNode(settings);
 
         assertThrows(client(node).admin().indices().prepareExists("test").setMasterNodeTimeout(TimeValue.timeValueSeconds(0)),

server/src/test/java/org/elasticsearch/cluster/MinimumMasterNodesIT.java

@@ -26,14 +26,13 @@
 import org.elasticsearch.action.admin.cluster.health.ClusterHealthResponse;
 import org.elasticsearch.client.Client;
 import org.elasticsearch.cluster.coordination.ClusterBootstrapService;
+import org.elasticsearch.cluster.coordination.FailedToCommitClusterStateException;
 import org.elasticsearch.cluster.metadata.MetaData;
 import org.elasticsearch.cluster.node.DiscoveryNode;
 import org.elasticsearch.cluster.service.ClusterService;
 import org.elasticsearch.common.Priority;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.discovery.DiscoverySettings;
-import org.elasticsearch.cluster.coordination.FailedToCommitClusterStateException;
-import org.elasticsearch.discovery.zen.ElectMasterService;
 import org.elasticsearch.discovery.zen.ZenDiscovery;
 import org.elasticsearch.index.query.QueryBuilders;
 import org.elasticsearch.node.Node;
@@ -102,7 +101,6 @@ public void testTwoNodesNoMasterBlock() throws Exception {
         bootstrapNodeId = 2;
 
         Settings settings = Settings.builder()
-                .put("discovery.zen.minimum_master_nodes", 2)
                 .put(ZenDiscovery.PING_TIMEOUT_SETTING.getKey(), "200ms")
                 .put("discovery.initial_state_timeout", "500ms")
                 .build();
@@ -237,7 +235,6 @@ public void testThreeNodesNoMasterBlock() throws Exception {
         bootstrapNodeId = 3;
 
         Settings settings = Settings.builder()
-                .put("discovery.zen.minimum_master_nodes", 3)
                 .put(ZenDiscovery.PING_TIMEOUT_SETTING.getKey(), "1s")
                 .put("discovery.initial_state_timeout", "500ms")
                 .build();
@@ -316,11 +313,9 @@ public void testCannotCommitStateThreeNodes() throws Exception {
         Settings settings = Settings.builder()
                 .put(ZenDiscovery.PING_TIMEOUT_SETTING.getKey(), "200ms")
                 .put("discovery.initial_state_timeout", "500ms")
-                .put(ElectMasterService.DISCOVERY_ZEN_MINIMUM_MASTER_NODES_SETTING.getKey(), 2)
                 .put(DiscoverySettings.COMMIT_TIMEOUT_SETTING.getKey(), "100ms") // speed things up
                 .build();
 
-
         internalCluster().startNodes(3, settings);
         ensureGreen(); // ensure cluster state is recovered before we disrupt things
 

server/src/test/java/org/elasticsearch/cluster/SpecificMasterNodesIT.java

@@ -38,7 +38,6 @@
 import java.util.Collections;
 import java.util.List;
 
-import static org.elasticsearch.discovery.zen.ElectMasterService.DISCOVERY_ZEN_MINIMUM_MASTER_NODES_SETTING;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcked;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.nullValue;
@@ -47,12 +46,6 @@
 @TestLogging("_root:DEBUG,org.elasticsearch.action.admin.cluster.state:TRACE")
 public class SpecificMasterNodesIT extends ESIntegTestCase {
 
-    @Override
-    protected Settings nodeSettings(int nodeOrdinal) {
-        return Settings.builder().put(super.nodeSettings(nodeOrdinal))
-            .put(DISCOVERY_ZEN_MINIMUM_MASTER_NODES_SETTING.getKey(), 1).build();
-    }
-
     @Override
     protected List<Settings> addExtraClusterBootstrapSettings(List<Settings> allNodesSettings) {
         // if it's the first master in the cluster bootstrap the cluster with this node name

server/src/test/java/org/elasticsearch/cluster/coordination/UnsafeBootstrapMasterIT.java

@@ -28,7 +28,6 @@
 import org.elasticsearch.cluster.metadata.MetaData;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.discovery.DiscoverySettings;
-import org.elasticsearch.discovery.zen.ElectMasterService;
 import org.elasticsearch.env.Environment;
 import org.elasticsearch.env.NodeEnvironment;
 import org.elasticsearch.env.NodeMetaData;
@@ -155,7 +154,6 @@ public void testNoNodeMetaData() throws IOException {
     public void testNotBootstrappedCluster() throws Exception {
         internalCluster().startNode(
                 Settings.builder()
-                        .put(ElectMasterService.DISCOVERY_ZEN_MINIMUM_MASTER_NODES_SETTING.getKey(), Integer.MAX_VALUE)
                         .put(DiscoverySettings.INITIAL_STATE_TIMEOUT_SETTING.getKey(), "0s") // to ensure quick node startup
                         .build());
         assertBusy(() -> {
@@ -172,9 +170,7 @@ public void testNotBootstrappedCluster() throws Exception {
 
     public void testNoManifestFile() throws IOException {
         bootstrapNodeId = 1;
-        internalCluster().startNode(Settings.builder()
-                .put(ElectMasterService.DISCOVERY_ZEN_MINIMUM_MASTER_NODES_SETTING.getKey(), Integer.MAX_VALUE)
-                .build());
+        internalCluster().startNode();
         ensureStableCluster(1);
         NodeEnvironment nodeEnvironment = internalCluster().getMasterNodeInstance(NodeEnvironment.class);
         internalCluster().stopRandomDataNode();
@@ -186,9 +182,7 @@ public void testNoManifestFile() throws IOException {
 
     public void testNoMetaData() throws IOException {
         bootstrapNodeId = 1;
-        internalCluster().startNode(Settings.builder()
-                .put(ElectMasterService.DISCOVERY_ZEN_MINIMUM_MASTER_NODES_SETTING.getKey(), Integer.MAX_VALUE)
-                .build());
+        internalCluster().startNode();
         ensureStableCluster(1);
         NodeEnvironment nodeEnvironment = internalCluster().getMasterNodeInstance(NodeEnvironment.class);
         internalCluster().stopRandomDataNode();
@@ -201,9 +195,7 @@ public void testNoMetaData() throws IOException {
 
     public void testAbortedByUser() throws IOException {
         bootstrapNodeId = 1;
-        internalCluster().startNode(Settings.builder()
-                .put(ElectMasterService.DISCOVERY_ZEN_MINIMUM_MASTER_NODES_SETTING.getKey(), Integer.MAX_VALUE)
-                .build());
+        internalCluster().startNode();
         ensureStableCluster(1);
         internalCluster().stopRandomDataNode();
 
@@ -213,13 +205,9 @@ public void testAbortedByUser() throws IOException {
 
     public void test3MasterNodes2Failed() throws Exception {
         bootstrapNodeId = 3;
-        List<String> masterNodes = internalCluster().startMasterOnlyNodes(3, Settings.builder()
-                .put(ElectMasterService.DISCOVERY_ZEN_MINIMUM_MASTER_NODES_SETTING.getKey(), Integer.MAX_VALUE)
-                .build());
+        List<String> masterNodes = internalCluster().startMasterOnlyNodes(3, Settings.EMPTY);
 
-        String dataNode = internalCluster().startDataOnlyNode(Settings.builder()
-                .put(ElectMasterService.DISCOVERY_ZEN_MINIMUM_MASTER_NODES_SETTING.getKey(), Integer.MAX_VALUE)
-                .build());
+        String dataNode = internalCluster().startDataOnlyNode();
         createIndex("test");
 
         Client dataNodeClient = internalCluster().client(dataNode);
@@ -246,9 +234,7 @@ public void test3MasterNodes2Failed() throws Exception {
                 String.format(Locale.ROOT, UnsafeBootstrapMasterCommand.CLUSTER_STATE_TERM_VERSION_MSG_FORMAT,
                         metaData.coordinationMetaData().term(), metaData.version())));
 
-        internalCluster().startMasterOnlyNode(Settings.builder()
-                .put(ElectMasterService.DISCOVERY_ZEN_MINIMUM_MASTER_NODES_SETTING.getKey(), Integer.MAX_VALUE)
-                .build());
+        internalCluster().startMasterOnlyNode();
 
         assertBusy(() -> {
             ClusterState state = dataNodeClient.admin().cluster().prepareState().setLocal(true)

server/src/test/java/org/elasticsearch/cluster/coordination/Zen1IT.java

@@ -34,6 +34,7 @@
 import org.elasticsearch.common.Priority;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.unit.TimeValue;
+import org.elasticsearch.discovery.zen.ElectMasterService;
 import org.elasticsearch.env.NodeEnvironment;
 import org.elasticsearch.gateway.MetaStateService;
 import org.elasticsearch.test.ESIntegTestCase;
@@ -50,6 +51,7 @@
 import static org.elasticsearch.cluster.routing.allocation.decider.EnableAllocationDecider.CLUSTER_ROUTING_ALLOCATION_ENABLE_SETTING;
 import static org.elasticsearch.cluster.routing.allocation.decider.FilterAllocationDecider.CLUSTER_ROUTING_EXCLUDE_GROUP_SETTING;
 import static org.elasticsearch.node.Node.NODE_NAME_SETTING;
+import static org.elasticsearch.test.InternalTestCluster.REMOVED_MINIMUM_MASTER_NODES;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.is;
 
@@ -194,7 +196,8 @@ public Settings onNodeStopped(String nodeName) {
                 }
                 ClusterHealthResponse clusterHealthResponse = clusterHealthRequestBuilder.get();
                 assertFalse(nodeName, clusterHealthResponse.isTimedOut());
-                return Coordinator.addZen1Attribute(false, Settings.builder().put(ZEN2_SETTINGS)).build();
+                return Coordinator.addZen1Attribute(false, Settings.builder().put(ZEN2_SETTINGS)
+                    .put(ElectMasterService.DISCOVERY_ZEN_MINIMUM_MASTER_NODES_SETTING.getKey(), REMOVED_MINIMUM_MASTER_NODES)).build();
             }
         });
 
@@ -289,6 +292,7 @@ public Settings onNodeStopped(String nodeName) throws Exception {
                 return Coordinator.addZen1Attribute(false, Settings.builder())
                     .put(ZEN2_SETTINGS)
                     .putList(INITIAL_MASTER_NODES_SETTING.getKey(), nodeNames)
+                    .put(ElectMasterService.DISCOVERY_ZEN_MINIMUM_MASTER_NODES_SETTING.getKey(), REMOVED_MINIMUM_MASTER_NODES)
                     .build();
             }
         });

server/src/test/java/org/elasticsearch/discovery/MasterDisruptionIT.java

@@ -35,7 +35,6 @@
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.unit.TimeValue;
 import org.elasticsearch.common.xcontent.XContentType;
-import org.elasticsearch.discovery.zen.ElectMasterService;
 import org.elasticsearch.discovery.zen.ZenDiscovery;
 import org.elasticsearch.monitor.jvm.HotThreads;
 import org.elasticsearch.test.ESIntegTestCase;
@@ -125,11 +124,6 @@ public void testNodesFDAfterMasterReelection() throws Exception {
 
         ensureStableCluster(3);
 
-        logger.info("--> reducing min master nodes to 2");
-        assertAcked(client().admin().cluster().prepareUpdateSettings()
-                .setTransientSettings(Settings.builder().put(ElectMasterService.DISCOVERY_ZEN_MINIMUM_MASTER_NODES_SETTING.getKey(), 2))
-                .get());
-
         String master = internalCluster().getMasterName();
         String nonMaster = null;
         for (String node : internalCluster().getNodeNames()) {
@@ -154,7 +148,7 @@ public void testNodesFDAfterMasterReelection() throws Exception {
      */
     @TestLogging("_root:DEBUG,org.elasticsearch.cluster.service:TRACE,org.elasticsearch.test.disruption:TRACE")
     public void testStaleMasterNotHijackingMajority() throws Exception {
-        // 3 node cluster with unicast discovery and minimum_master_nodes set to the default of 2:
+        // 3 node cluster with unicast discovery:
         final List<String> nodes = startCluster(3);
 
         // Save the current master node as old master node, because that node will get frozen