Remove some leftover refs to minimum_master_nodes (#42700)

Today `InternalTestCluster` has a few vestigial mentions of the
`minimum_master_nodes` setting. This commit removes them and simplifies some of
the surrounding logic.

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

@@ -47,7 +47,7 @@ import static org.hamcrest.core.Is.is;
 // These tests are here today so they have access to a proper REST client. They cannot be in :server:integTest since the REST client needs a
 // proper transport implementation, and they cannot be REST tests today since they need to restart nodes. When #35599 and friends land we
 // should be able to move these tests to run against a proper cluster instead. TODO do this.
-@ESIntegTestCase.ClusterScope(scope = ESIntegTestCase.Scope.TEST, numDataNodes = 0, autoMinMasterNodes = false)
+@ESIntegTestCase.ClusterScope(scope = ESIntegTestCase.Scope.TEST, numDataNodes = 0, autoManageMasterNodes = false)
 public class Zen2RestApiIT extends ESNetty4IntegTestCase {
 
     @Override

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

@@ -30,7 +30,7 @@ import org.elasticsearch.test.InternalTestCluster;
 import java.io.IOException;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertThrows;
 
-@ClusterScope(scope = ESIntegTestCase.Scope.TEST, numDataNodes = 0, numClientNodes = 0, autoMinMasterNodes = false)
+@ClusterScope(scope = ESIntegTestCase.Scope.TEST, numDataNodes = 0, numClientNodes = 0, autoManageMasterNodes = false)
 public class IndicesExistsIT extends ESIntegTestCase {
 
     public void testIndexExistsWithBlocksInPlace() throws IOException {

server/src/test/java/org/elasticsearch/action/support/master/IndexingMasterFailoverIT.java

@@ -39,7 +39,7 @@ import java.util.concurrent.CyclicBarrier;
 
 import static org.hamcrest.Matchers.equalTo;
 
-@ESIntegTestCase.ClusterScope(scope = ESIntegTestCase.Scope.TEST, numDataNodes = 0, autoMinMasterNodes = false)
+@ESIntegTestCase.ClusterScope(scope = ESIntegTestCase.Scope.TEST, numDataNodes = 0, autoManageMasterNodes = false)
 public class IndexingMasterFailoverIT extends ESIntegTestCase {
 
     @Override

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

@@ -62,7 +62,7 @@ import static org.hamcrest.Matchers.not;
 import static org.hamcrest.Matchers.notNullValue;
 import static org.hamcrest.Matchers.nullValue;
 
-@ClusterScope(scope = Scope.TEST, numDataNodes = 0, autoMinMasterNodes = false)
+@ClusterScope(scope = Scope.TEST, numDataNodes = 0, autoManageMasterNodes = false)
 @TestLogging("_root:DEBUG,org.elasticsearch.cluster.service:TRACE,org.elasticsearch.cluster.coordination:TRACE")
 public class MinimumMasterNodesIT extends ESIntegTestCase {
 

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

@@ -39,7 +39,7 @@ import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcke
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.nullValue;
 
-@ClusterScope(scope = Scope.TEST, numDataNodes = 0, autoMinMasterNodes = false)
+@ClusterScope(scope = Scope.TEST, numDataNodes = 0, autoManageMasterNodes = false)
 @TestLogging("_root:DEBUG,org.elasticsearch.action.admin.cluster.state:TRACE")
 public class SpecificMasterNodesIT extends ESIntegTestCase {
 

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

@@ -52,7 +52,7 @@ import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.greaterThan;
 
-@ESIntegTestCase.ClusterScope(scope = ESIntegTestCase.Scope.TEST, numDataNodes = 0, autoMinMasterNodes = false)
+@ESIntegTestCase.ClusterScope(scope = ESIntegTestCase.Scope.TEST, numDataNodes = 0, autoManageMasterNodes = false)
 @TestLogging("_root:DEBUG,org.elasticsearch.cluster.service:TRACE,org.elasticsearch.cluster.coordination:TRACE")
 public class UnsafeBootstrapAndDetachCommandIT extends ESIntegTestCase {
 

server/src/test/java/org/elasticsearch/discovery/single/SingleNodeDiscoveryIT.java

@@ -50,7 +50,7 @@ import static org.hamcrest.Matchers.not;
         numDataNodes = 1,
         numClientNodes = 0,
         supportsDedicatedMasters = false,
-        autoMinMasterNodes = false)
+        autoManageMasterNodes = false)
 public class SingleNodeDiscoveryIT extends ESIntegTestCase {
 
     @Override

server/src/test/java/org/elasticsearch/gateway/RecoverAfterNodesIT.java

@@ -34,7 +34,7 @@ import java.util.Set;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.hasItem;
 
-@ClusterScope(scope = Scope.TEST, numDataNodes = 0, autoMinMasterNodes = false)
+@ClusterScope(scope = Scope.TEST, numDataNodes = 0, autoManageMasterNodes = false)
 public class RecoverAfterNodesIT extends ESIntegTestCase {
     private static final TimeValue BLOCK_WAIT_TIMEOUT = TimeValue.timeValueSeconds(10);
 

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

@@ -1608,9 +1608,10 @@ public abstract class ESIntegTestCase extends ESTestCase {
         boolean supportsDedicatedMasters() default true;
 
         /**
-         * The cluster automatically manages the bootstrap voting configuration. Set this to false to manage the setting manually.
+         * Indicates whether the cluster automatically manages cluster bootstrapping and the removal of any master-eligible nodes. If
+         * set to {@code false} then the tests must manage these processes explicitly.
          */
-        boolean autoMinMasterNodes() default true;
+        boolean autoManageMasterNodes() default true;
 
         /**
          * Returns the number of client nodes in the cluster. Default is {@link InternalTestCluster#DEFAULT_NUM_CLIENT_NODES}, a
@@ -1698,9 +1699,9 @@ public abstract class ESIntegTestCase extends ESTestCase {
         return annotation == null ? true : annotation.supportsDedicatedMasters();
     }
 
-    private boolean getAutoMinMasterNodes() {
+    private boolean getAutoManageMasterNodes() {
         ClusterScope annotation = getAnnotation(this.getClass(), ClusterScope.class);
-        return annotation == null ? true : annotation.autoMinMasterNodes();
+        return annotation == null ? true : annotation.autoManageMasterNodes();
     }
 
     private int getNumDataNodes() {
@@ -1838,7 +1839,7 @@ public abstract class ESIntegTestCase extends ESTestCase {
             }
             mockPlugins = mocks;
         }
-        return new InternalTestCluster(seed, createTempDir(), supportsDedicatedMasters, getAutoMinMasterNodes(),
+        return new InternalTestCluster(seed, createTempDir(), supportsDedicatedMasters, getAutoManageMasterNodes(),
             minNumDataNodes, maxNumDataNodes,
             InternalTestCluster.clusterName(scope.name(), seed) + "-cluster", nodeConfigurationSource, getNumClientNodes(),
             nodePrefix, mockPlugins, getClientWrapper(), forbidPrivateIndexSettings());

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

@@ -227,7 +227,7 @@ public final class InternalTestCluster extends TestCluster {
 
     private final ExecutorService executor;
 
-    private final boolean autoManageMinMasterNodes;
+    private final boolean autoManageMasterNodes;
 
     private final Collection<Class<? extends Plugin>> mockPlugins;
 
@@ -250,7 +250,7 @@ public final class InternalTestCluster extends TestCluster {
             final long clusterSeed,
             final Path baseDir,
             final boolean randomlyAddDedicatedMasters,
-            final boolean autoManageMinMasterNodes,
+            final boolean autoManageMasterNodes,
             final int minNumDataNodes,
             final int maxNumDataNodes,
             final String clusterName,
@@ -263,7 +263,7 @@ public final class InternalTestCluster extends TestCluster {
                 clusterSeed,
                 baseDir,
                 randomlyAddDedicatedMasters,
-                autoManageMinMasterNodes,
+                autoManageMasterNodes,
                 minNumDataNodes,
                 maxNumDataNodes,
                 clusterName,
@@ -279,7 +279,7 @@ public final class InternalTestCluster extends TestCluster {
             final long clusterSeed,
             final Path baseDir,
             final boolean randomlyAddDedicatedMasters,
-            final boolean autoManageMinMasterNodes,
+            final boolean autoManageMasterNodes,
             final int minNumDataNodes,
             final int maxNumDataNodes,
             final String clusterName,
@@ -290,7 +290,7 @@ public final class InternalTestCluster extends TestCluster {
             final Function<Client, Client> clientWrapper,
             final boolean forbidPrivateIndexSettings) {
         super(clusterSeed);
-        this.autoManageMinMasterNodes = autoManageMinMasterNodes;
+        this.autoManageMasterNodes = autoManageMasterNodes;
         this.clientWrapper = clientWrapper;
         this.forbidPrivateIndexSettings = forbidPrivateIndexSettings;
         this.baseDir = baseDir;
@@ -305,7 +305,7 @@ public final class InternalTestCluster extends TestCluster {
 
         Random random = new Random(clusterSeed);
 
-        boolean useDedicatedMasterNodes = randomlyAddDedicatedMasters ? random.nextBoolean() : false;
+        boolean useDedicatedMasterNodes = randomlyAddDedicatedMasters && random.nextBoolean();
 
         this.numSharedDataNodes = RandomNumbers.randomIntBetween(random, minNumDataNodes, maxNumDataNodes);
         assert this.numSharedDataNodes >= 0;
@@ -345,10 +345,10 @@ public final class InternalTestCluster extends TestCluster {
         }
 
         logger.info("Setup InternalTestCluster [{}] with seed [{}] using [{}] dedicated masters, " +
-                "[{}] (data) nodes and [{}] coord only nodes (min_master_nodes are [{}])",
+                "[{}] (data) nodes and [{}] coord only nodes (master nodes are [{}])",
             clusterName, SeedUtils.formatSeed(clusterSeed),
             numSharedDedicatedMasterNodes, numSharedDataNodes, numSharedCoordOnlyNodes,
-            autoManageMinMasterNodes ? "auto-managed" : "manual");
+            autoManageMasterNodes ? "auto-managed" : "manual");
         this.nodeConfigurationSource = nodeConfigurationSource;
         numDataPaths = random.nextInt(5) == 0 ? 2 + random.nextInt(3) : 1;
         Builder builder = Settings.builder();
@@ -394,12 +394,11 @@ public final class InternalTestCluster extends TestCluster {
     /**
      * Sets {@link #bootstrapMasterNodeIndex} to the given value, see {@link #bootstrapMasterNodeWithSpecifiedIndex(List)}
      * for the description of how this field is used.
-     * It's only possible to change {@link #bootstrapMasterNodeIndex} value if autoManageMinMasterNodes is false.
+     * It's only possible to change {@link #bootstrapMasterNodeIndex} value if autoManageMasterNodes is false.
      */
     public void setBootstrapMasterNodeIndex(int bootstrapMasterNodeIndex) {
-        if (autoManageMinMasterNodes && bootstrapMasterNodeIndex != -1) {
-            throw new AssertionError("bootstrapMasterNodeIndex should be -1 if autoManageMinMasterNodes is true");
-        }
+        assert autoManageMasterNodes == false || bootstrapMasterNodeIndex == -1
+            : "bootstrapMasterNodeIndex should be -1 if autoManageMasterNodes is true, but was " + bootstrapMasterNodeIndex;
         this.bootstrapMasterNodeIndex = bootstrapMasterNodeIndex;
     }
 
@@ -531,7 +530,7 @@ public final class InternalTestCluster extends TestCluster {
         final Runnable onTransportServiceStarted = () -> {}; // do not create unicast host file for this one node.
 
         final int nodeId = nextNodeId.getAndIncrement();
-        final Settings settings = getNodeSettings(nodeId, random.nextLong(), Settings.EMPTY, 1);
+        final Settings settings = getNodeSettings(nodeId, random.nextLong(), Settings.EMPTY);
         final Settings nodeSettings = Settings.builder()
                 .putList(INITIAL_MASTER_NODES_SETTING.getKey(), Node.NODE_NAME_SETTING.get(settings))
                 .put(settings)
@@ -605,7 +604,7 @@ public final class InternalTestCluster extends TestCluster {
         }
     }
 
-    private Settings getNodeSettings(final int nodeId, final long seed, final Settings extraSettings, final int defaultMinMasterNodes) {
+    private Settings getNodeSettings(final int nodeId, final long seed, final Settings extraSettings) {
         final Settings settings = getSettings(nodeId, seed, extraSettings);
 
         final String name = buildNodeName(nodeId, settings);
@@ -629,8 +628,8 @@ public final class InternalTestCluster extends TestCluster {
         updatedSettings.put("node.name", name);
         updatedSettings.put(NodeEnvironment.NODE_ID_SEED_SETTING.getKey(), seed);
 
-        if (autoManageMinMasterNodes) {
-            assertThat("automatically managing min master nodes require nodes to complete a join cycle when starting",
+        if (autoManageMasterNodes) {
+            assertThat("if master nodes are automatically managed then nodes must complete a join cycle when starting",
                 updatedSettings.get(INITIAL_STATE_TIMEOUT_SETTING.getKey()), nullValue());
         }
 
@@ -810,8 +809,6 @@ public final class InternalTestCluster extends TestCluster {
         }
     }
 
-    private static final int REMOVED_MINIMUM_MASTER_NODES = Integer.MAX_VALUE;
-
     private final class NodeAndClient implements Closeable {
         private MockNode node;
         private final Settings originalNodeSettings;
@@ -889,18 +886,16 @@ public final class InternalTestCluster extends TestCluster {
         /**
          * closes the node and prepares it to be restarted
          */
-        Settings closeForRestart(RestartCallback callback, int minMasterNodes) throws Exception {
+        Settings closeForRestart(RestartCallback callback) throws Exception {
             assert callback != null;
             close();
             Settings callbackSettings = callback.onNodeStopped(name);
             assert callbackSettings != null;
             Settings.Builder newSettings = Settings.builder();
-            newSettings.put(callbackSettings);
-            if (minMasterNodes >= 0) {
-                if (INITIAL_MASTER_NODES_SETTING.exists(callbackSettings) == false) {
-                    newSettings.putList(INITIAL_MASTER_NODES_SETTING.getKey());
-                }
+            if (autoManageMasterNodes) {
+                newSettings.putList(INITIAL_MASTER_NODES_SETTING.getKey());
             }
+            newSettings.put(callbackSettings);
             // delete data folders now, before we start other nodes that may claim it
             clearDataIfNeeded(callback);
             return newSettings.build();
@@ -1026,9 +1021,7 @@ public final class InternalTestCluster extends TestCluster {
 
         // start any missing node
         assert newSize == numSharedDedicatedMasterNodes + numSharedDataNodes + numSharedCoordOnlyNodes;
-        final int numberOfMasterNodes = numSharedDedicatedMasterNodes > 0 ? numSharedDedicatedMasterNodes : numSharedDataNodes;
-        final int defaultMinMasterNodes = (numberOfMasterNodes / 2) + 1;
-        final List<NodeAndClient> toStartAndPublish = new ArrayList<>(); // we want to start nodes in one go due to min master nodes
+        final List<NodeAndClient> toStartAndPublish = new ArrayList<>(); // we want to start nodes in one go
         final Runnable onTransportServiceStarted = () -> rebuildUnicastHostFiles(toStartAndPublish);
 
         final List<Settings> settings = new ArrayList<>();
@@ -1037,7 +1030,7 @@ public final class InternalTestCluster extends TestCluster {
             final Settings.Builder extraSettings = Settings.builder();
             extraSettings.put(Node.NODE_MASTER_SETTING.getKey(), true);
             extraSettings.put(Node.NODE_DATA_SETTING.getKey(), false);
-            settings.add(getNodeSettings(i, sharedNodesSeeds[i], extraSettings.build(), defaultMinMasterNodes));
+            settings.add(getNodeSettings(i, sharedNodesSeeds[i], extraSettings.build()));
         }
         for (int i = numSharedDedicatedMasterNodes; i < numSharedDedicatedMasterNodes + numSharedDataNodes; i++) {
             final Settings.Builder extraSettings = Settings.builder();
@@ -1046,13 +1039,13 @@ public final class InternalTestCluster extends TestCluster {
                 extraSettings.put(Node.NODE_MASTER_SETTING.getKey(), false).build();
                 extraSettings.put(Node.NODE_DATA_SETTING.getKey(), true).build();
             }
-            settings.add(getNodeSettings(i, sharedNodesSeeds[i], extraSettings.build(), defaultMinMasterNodes));
+            settings.add(getNodeSettings(i, sharedNodesSeeds[i], extraSettings.build()));
         }
         for (int i = numSharedDedicatedMasterNodes + numSharedDataNodes;
              i < numSharedDedicatedMasterNodes + numSharedDataNodes + numSharedCoordOnlyNodes; i++) {
             final Builder extraSettings = Settings.builder().put(Node.NODE_MASTER_SETTING.getKey(), false)
                 .put(Node.NODE_DATA_SETTING.getKey(), false).put(Node.NODE_INGEST_SETTING.getKey(), false);
-            settings.add(getNodeSettings(i, sharedNodesSeeds[i], extraSettings.build(), defaultMinMasterNodes));
+            settings.add(getNodeSettings(i, sharedNodesSeeds[i], extraSettings.build()));
         }
 
         int autoBootstrapMasterNodeIndex = -1;
@@ -1061,7 +1054,7 @@ public final class InternalTestCluster extends TestCluster {
                 .map(Node.NODE_NAME_SETTING::get)
                 .collect(Collectors.toList());
 
-        if (prevNodeCount == 0 && autoManageMinMasterNodes) {
+        if (prevNodeCount == 0 && autoManageMasterNodes) {
             if (numSharedDedicatedMasterNodes > 0) {
                 autoBootstrapMasterNodeIndex = RandomNumbers.randomIntBetween(random, 0, numSharedDedicatedMasterNodes - 1);
             } else if (numSharedDataNodes > 0) {
@@ -1084,7 +1077,7 @@ public final class InternalTestCluster extends TestCluster {
 
         nextNodeId.set(newSize);
         assert size() == newSize;
-        if (autoManageMinMasterNodes && newSize > 0) {
+        if (autoManageMasterNodes && newSize > 0) {
             validateClusterFormed();
         }
         logger.debug("Cluster is consistent again - nodes: [{}] nextNodeId: [{}] numSharedNodes: [{}]",
@@ -1469,7 +1462,7 @@ public final class InternalTestCluster extends TestCluster {
         for (HttpServerTransport httpServerTransport : getInstances(HttpServerTransport.class)) {
             addresses.add(httpServerTransport.boundAddress().publishAddress().address());
         }
-        return addresses.toArray(new InetSocketAddress[addresses.size()]);
+        return addresses.toArray(new InetSocketAddress[0]);
     }
 
     /**
@@ -1543,8 +1536,7 @@ public final class InternalTestCluster extends TestCluster {
             }
             nodeAndClients.forEach(this::publishNode);
 
-            if (autoManageMinMasterNodes && currentMasters > 0 && newMasters > 0 &&
-                getMinMasterNodes(currentMasters + newMasters) > currentMasters) {
+            if (autoManageMasterNodes && newMasters > 0) {
                 // update once masters have joined
                 validateClusterFormed();
             }
@@ -1652,11 +1644,8 @@ public final class InternalTestCluster extends TestCluster {
             activeDisruptionScheme.removeFromNode(nodeAndClient.name, this);
         }
 
-        Set<String> excludedNodeIds = excludeMasters(Collections.singleton(nodeAndClient));
-
-        final Settings newSettings = nodeAndClient.closeForRestart(callback,
-                autoManageMinMasterNodes ? getMinMasterNodes(getMasterNodesCount()) : -1);
-
+        final Set<String> excludedNodeIds = excludeMasters(Collections.singleton(nodeAndClient));
+        final Settings newSettings = nodeAndClient.closeForRestart(callback);
         removeExclusions(excludedNodeIds);
 
         boolean success = false;
@@ -1675,10 +1664,8 @@ public final class InternalTestCluster extends TestCluster {
         }
 
         if (callback.validateClusterForming() || excludedNodeIds.isEmpty() == false) {
-            // we have to validate cluster size if updateMinMaster == true, because we need the
-            // second node to join in order to increment min_master_nodes back to 2.
-            // we also have to do via the node that was just restarted as it may be that the master didn't yet process
-            // the fact it left
+            // we have to validate cluster size to ensure that the restarted node has rejoined the cluster if it was master-eligible;
+            // we have to do this via the node that was just restarted as it may be that the master didn't yet process the fact that it left
             validateClusterFormed(nodeAndClient.name);
         }
     }
@@ -1694,7 +1681,7 @@ public final class InternalTestCluster extends TestCluster {
     private Set<String> excludeMasters(Collection<NodeAndClient> nodeAndClients) {
         assert Thread.holdsLock(this);
         final Set<String> excludedNodeIds = new HashSet<>();
-        if (autoManageMinMasterNodes && nodeAndClients.size() > 0) {
+        if (autoManageMasterNodes && nodeAndClients.size() > 0) {
 
             final long currentMasters = nodes.values().stream().filter(NodeAndClient::isMasterEligible).count();
             final long stoppingMasters = nodeAndClients.stream().filter(NodeAndClient::isMasterEligible).count();
@@ -1741,7 +1728,6 @@ public final class InternalTestCluster extends TestCluster {
         final Settings[] newNodeSettings = new Settings[nextNodeId.get()];
         Map<Set<Role>, List<NodeAndClient>> nodesByRoles = new HashMap<>();
         Set[] rolesOrderedByOriginalStartupOrder = new Set[nextNodeId.get()];
-        final int minMasterNodes = autoManageMinMasterNodes ? getMinMasterNodes(getMasterNodesCount()) : -1;
         for (NodeAndClient nodeAndClient : nodes.values()) {
             callback.doAfterNodes(numNodesRestarted++, nodeAndClient.nodeClient());
             logger.info("Stopping and resetting node [{}] ", nodeAndClient.name);
@@ -1749,7 +1735,7 @@ public final class InternalTestCluster extends TestCluster {
                 activeDisruptionScheme.removeFromNode(nodeAndClient.name, this);
             }
             DiscoveryNode discoveryNode = getInstanceFromNode(ClusterService.class, nodeAndClient.node()).localNode();
-            final Settings newSettings = nodeAndClient.closeForRestart(callback, minMasterNodes);
+            final Settings newSettings = nodeAndClient.closeForRestart(callback);
             newNodeSettings[nodeAndClient.nodeAndClientId()] = newSettings;
             rolesOrderedByOriginalStartupOrder[nodeAndClient.nodeAndClientId()] = discoveryNode.getRoles();
             nodesByRoles.computeIfAbsent(discoveryNode.getRoles(), k -> new ArrayList<>()).add(nodeAndClient);
@@ -1934,25 +1920,18 @@ public final class InternalTestCluster extends TestCluster {
      */
     public synchronized List<String> startNodes(Settings... extraSettings) {
         final int newMasterCount = Math.toIntExact(Stream.of(extraSettings).filter(Node.NODE_MASTER_SETTING::get).count());
-        final int defaultMinMasterNodes;
-        if (autoManageMinMasterNodes) {
-            defaultMinMasterNodes = getMinMasterNodes(getMasterNodesCount() + newMasterCount);
-        } else {
-            defaultMinMasterNodes = -1;
-        }
         final List<NodeAndClient> nodes = new ArrayList<>();
         final int prevMasterCount = getMasterNodesCount();
-        int autoBootstrapMasterNodeIndex =
-                prevMasterCount == 0 && autoManageMinMasterNodes && newMasterCount > 0 && Arrays.stream(extraSettings)
-            .allMatch(s -> Node.NODE_MASTER_SETTING.get(s) == false
-                || ZEN2_DISCOVERY_TYPE.equals(DISCOVERY_TYPE_SETTING.get(s)))
+        int autoBootstrapMasterNodeIndex = autoManageMasterNodes && prevMasterCount == 0 && newMasterCount > 0
+            && Arrays.stream(extraSettings)
+                    .allMatch(s -> Node.NODE_MASTER_SETTING.get(s) == false || ZEN2_DISCOVERY_TYPE.equals(DISCOVERY_TYPE_SETTING.get(s)))
             ? RandomNumbers.randomIntBetween(random, 0, newMasterCount - 1) : -1;
 
         final int numOfNodes = extraSettings.length;
         final int firstNodeId = nextNodeId.getAndIncrement();
         final List<Settings> settings = new ArrayList<>();
         for (int i = 0; i < numOfNodes; i++) {
-            settings.add(getNodeSettings(firstNodeId + i, random.nextLong(), extraSettings[i], defaultMinMasterNodes));
+            settings.add(getNodeSettings(firstNodeId + i, random.nextLong(), extraSettings[i]));
         }
         nextNodeId.set(firstNodeId + numOfNodes);
 
@@ -1978,7 +1957,7 @@ public final class InternalTestCluster extends TestCluster {
             nodes.add(nodeAndClient);
         }
         startAndPublishNodesAndClients(nodes);
-        if (autoManageMinMasterNodes) {
+        if (autoManageMasterNodes) {
             validateClusterFormed();
         }
         return nodes.stream().map(NodeAndClient::getName).collect(Collectors.toList());
@@ -2004,11 +1983,6 @@ public final class InternalTestCluster extends TestCluster {
                 .put(Node.NODE_DATA_SETTING.getKey(), true).build());
     }
 
-    /** calculates a min master nodes value based on the given number of master nodes */
-    private static int getMinMasterNodes(int eligibleMasterNodes) {
-        return eligibleMasterNodes / 2 + 1;
-    }
-
     private int getMasterNodesCount() {
         return (int) nodes.values().stream().filter(n -> Node.NODE_MASTER_SETTING.get(n.node().settings())).count();
     }
@@ -2143,7 +2117,7 @@ public final class InternalTestCluster extends TestCluster {
                         greaterThan(shard));
                 OperationRouting operationRouting = clusterService.operationRouting();
                 while (true) {
-                    String routing = RandomStrings.randomAsciiOfLength(random, 10);
+                    String routing = RandomStrings.randomAsciiLettersOfLength(random, 10);
                     final int targetShard = operationRouting
                             .indexShards(clusterService.state(), index.getName(), null, routing)
                             .shardId().getId();

test/framework/src/test/java/org/elasticsearch/test/disruption/NetworkDisruptionIT.java

@@ -37,7 +37,7 @@ import java.util.Set;
 
 import static org.hamcrest.Matchers.greaterThanOrEqualTo;
 
-@ESIntegTestCase.ClusterScope(scope = ESIntegTestCase.Scope.TEST, numDataNodes = 0, autoMinMasterNodes = false)
+@ESIntegTestCase.ClusterScope(scope = ESIntegTestCase.Scope.TEST, numDataNodes = 0, autoManageMasterNodes = false)
 public class NetworkDisruptionIT extends ESIntegTestCase {
     @Override
     protected Collection<Class<? extends Plugin>> nodePlugins() {