diff --git a/client/rest-high-level/src/test/java/org/elasticsearch/client/ClusterClientIT.java b/client/rest-high-level/src/test/java/org/elasticsearch/client/ClusterClientIT.java
index 2ae6f9dc186..2a870ec65ee 100644
--- a/client/rest-high-level/src/test/java/org/elasticsearch/client/ClusterClientIT.java
+++ b/client/rest-high-level/src/test/java/org/elasticsearch/client/ClusterClientIT.java
@@ -129,7 +129,6 @@ public class ClusterClientIT extends ESRestHighLevelClientTestCase {
         createIndex("index2", Settings.EMPTY);
         ClusterHealthRequest request = new ClusterHealthRequest();
         request.timeout("5s");
-        request.level(ClusterHealthRequest.Level.CLUSTER);
         ClusterHealthResponse response = execute(request, highLevelClient().cluster()::health, highLevelClient().cluster()::healthAsync);
 
         assertYellowShards(response);
@@ -170,6 +169,7 @@ public class ClusterClientIT extends ESRestHighLevelClientTestCase {
         createIndex("index", Settings.EMPTY);
         createIndex("index2", Settings.EMPTY);
         ClusterHealthRequest request = new ClusterHealthRequest("index");
+        request.level(ClusterHealthRequest.Level.SHARDS);
         request.timeout("5s");
         ClusterHealthResponse response = execute(request, highLevelClient().cluster()::health, highLevelClient().cluster()::healthAsync);
 
diff --git a/client/rest-high-level/src/test/java/org/elasticsearch/client/RequestConvertersTests.java b/client/rest-high-level/src/test/java/org/elasticsearch/client/RequestConvertersTests.java
index 5bc9bac96dc..aa8221f3099 100644
--- a/client/rest-high-level/src/test/java/org/elasticsearch/client/RequestConvertersTests.java
+++ b/client/rest-high-level/src/test/java/org/elasticsearch/client/RequestConvertersTests.java
@@ -1568,7 +1568,7 @@ public class RequestConvertersTests extends ESTestCase {
             healthRequest.level(level);
             expectedParams.put("level", level.name().toLowerCase(Locale.ROOT));
         } else {
-            expectedParams.put("level", "shards");
+            expectedParams.put("level", "cluster");
         }
         if (randomBoolean()) {
             Priority priority = randomFrom(Priority.values());
diff --git a/docs/java-rest/high-level/cluster/health.asciidoc b/docs/java-rest/high-level/cluster/health.asciidoc
index 6c0f926f15f..192880849e2 100644
--- a/docs/java-rest/high-level/cluster/health.asciidoc
+++ b/docs/java-rest/high-level/cluster/health.asciidoc
@@ -67,6 +67,7 @@ include-tagged::{doc-tests}/ClusterClientDocumentationIT.java[health-request-wai
 include-tagged::{doc-tests}/ClusterClientDocumentationIT.java[health-request-level]
 --------------------------------------------------
 <1> The level of detail of the returned health information. Accepts a `ClusterHealthRequest.Level` value.
+Default value is `cluster`.
 
 ["source","java",subs="attributes,callouts,macros"]
 --------------------------------------------------
diff --git a/docs/reference/migration/migrate_7_0/restclient.asciidoc b/docs/reference/migration/migrate_7_0/restclient.asciidoc
index 146b0d73386..470996cfeff 100644
--- a/docs/reference/migration/migrate_7_0/restclient.asciidoc
+++ b/docs/reference/migration/migrate_7_0/restclient.asciidoc
@@ -10,4 +10,11 @@ header, e.g. `client.index(indexRequest)` becomes
 `client.index(indexRequest, RequestOptions.DEFAULT)`.
 In case you are specifying headers
 e.g. `client.index(indexRequest, new Header("name" "value"))` becomes
-`client.index(indexRequest, RequestOptions.DEFAULT.toBuilder().addHeader("name", "value").build());`
\ No newline at end of file
+`client.index(indexRequest, RequestOptions.DEFAULT.toBuilder().addHeader("name", "value").build());`
+
+==== Cluster Health API default to `cluster` level
+
+The Cluster Health API used to default to `shards` level to ease migration
+from transport client that doesn't support the `level` parameter and always
+returns information including indices and shards details. The level default
+value has been aligned with the Elasticsearch default level: `cluster`.
\ No newline at end of file
diff --git a/server/src/main/java/org/elasticsearch/action/admin/cluster/health/ClusterHealthRequest.java b/server/src/main/java/org/elasticsearch/action/admin/cluster/health/ClusterHealthRequest.java
index 59a291888d0..0b9bcbf11b9 100644
--- a/server/src/main/java/org/elasticsearch/action/admin/cluster/health/ClusterHealthRequest.java
+++ b/server/src/main/java/org/elasticsearch/action/admin/cluster/health/ClusterHealthRequest.java
@@ -48,9 +48,9 @@ public class ClusterHealthRequest extends MasterNodeReadRequest<ClusterHealthReq
     private Priority waitForEvents = null;
     /**
      * Only used by the high-level REST Client. Controls the details level of the health information returned.
-     * The default value is 'shards' so it is backward compatible with the transport client behaviour.
+     * The default value is 'cluster'.
      */
-    private Level level = Level.SHARDS;
+    private Level level = Level.CLUSTER;
 
     public ClusterHealthRequest() {
     }
@@ -250,8 +250,7 @@ public class ClusterHealthRequest extends MasterNodeReadRequest<ClusterHealthReq
 
     /**
      * Set the level of detail for the health information to be returned.
-     * Only used by the high-level REST Client
-     * The default value is 'shards' so it is backward compatible with the transport client behaviour.
+     * Only used by the high-level REST Client.
      */
     public void level(Level level) {
         this.level = Objects.requireNonNull(level, "level must not be null");
@@ -260,7 +259,6 @@ public class ClusterHealthRequest extends MasterNodeReadRequest<ClusterHealthReq
     /**
      * Get the level of detail for the health information to be returned.
      * Only used by the high-level REST Client.
-     * The default value is 'shards' so it is backward compatible with the transport client behaviour.
      */
     public Level level() {
         return level;
diff --git a/server/src/main/java/org/elasticsearch/cluster/metadata/MetaDataUpdateSettingsService.java b/server/src/main/java/org/elasticsearch/cluster/metadata/MetaDataUpdateSettingsService.java
index ce5ad12a53d..38766c08e08 100644
--- a/server/src/main/java/org/elasticsearch/cluster/metadata/MetaDataUpdateSettingsService.java
+++ b/server/src/main/java/org/elasticsearch/cluster/metadata/MetaDataUpdateSettingsService.java
@@ -82,8 +82,10 @@ public class MetaDataUpdateSettingsService extends AbstractComponent {
         Settings.Builder settingsForOpenIndices = Settings.builder();
         final Set<String> skippedSettings = new HashSet<>();
 
-        indexScopedSettings.validate(normalizedSettings.filter(s -> Regex.isSimpleMatchPattern(s) == false  /* don't validate wildcards */),
-            false); //don't validate dependencies here we check it below never allow to change the number of shards
+        indexScopedSettings.validate(
+                normalizedSettings.filter(s -> Regex.isSimpleMatchPattern(s) == false), // don't validate wildcards
+                false, // don't validate dependencies here we check it below never allow to change the number of shards
+                true); // validate internal index settings
         for (String key : normalizedSettings.keySet()) {
             Setting setting = indexScopedSettings.get(key);
             boolean isWildcard = setting == null && Regex.isSimpleMatchPattern(key);
diff --git a/server/src/main/java/org/elasticsearch/common/settings/AbstractScopedSettings.java b/server/src/main/java/org/elasticsearch/common/settings/AbstractScopedSettings.java
index e8bb946c8a7..eb4e2946424 100644
--- a/server/src/main/java/org/elasticsearch/common/settings/AbstractScopedSettings.java
+++ b/server/src/main/java/org/elasticsearch/common/settings/AbstractScopedSettings.java
@@ -282,6 +282,18 @@ public abstract class AbstractScopedSettings extends AbstractComponent {
         validate(settings, validateDependencies, false, false);
     }
 
+    /**
+     * Validates that all settings are registered and valid.
+     *
+     * @param settings              the settings to validate
+     * @param validateDependencies  true if dependent settings should be validated
+     * @param validateInternalIndex true if internal index settings should be validated
+     * @see Setting#getSettingsDependencies(String)
+     */
+    public final void validate(final Settings settings, final boolean validateDependencies, final boolean validateInternalIndex) {
+        validate(settings, validateDependencies, false, false, validateInternalIndex);
+    }
+
     /**
      * Validates that all settings are registered and valid.
      *
@@ -296,6 +308,25 @@ public abstract class AbstractScopedSettings extends AbstractComponent {
             final boolean validateDependencies,
             final boolean ignorePrivateSettings,
             final boolean ignoreArchivedSettings) {
+        validate(settings, validateDependencies, ignorePrivateSettings, ignoreArchivedSettings, false);
+    }
+
+    /**
+     * Validates that all settings are registered and valid.
+     *
+     * @param settings               the settings
+     * @param validateDependencies   true if dependent settings should be validated
+     * @param ignorePrivateSettings  true if private settings should be ignored during validation
+     * @param ignoreArchivedSettings true if archived settings should be ignored during validation
+     * @param validateInternalIndex  true if index internal settings should be validated
+     * @see Setting#getSettingsDependencies(String)
+     */
+    public final void validate(
+            final Settings settings,
+            final boolean validateDependencies,
+            final boolean ignorePrivateSettings,
+            final boolean ignoreArchivedSettings,
+            final boolean validateInternalIndex) {
         final List<RuntimeException> exceptions = new ArrayList<>();
         for (final String key : settings.keySet()) { // settings iterate in deterministic fashion
             if (isPrivateSetting(key) && ignorePrivateSettings) {
@@ -305,7 +336,7 @@ public abstract class AbstractScopedSettings extends AbstractComponent {
                 continue;
             }
             try {
-                validate(key, settings, validateDependencies);
+                validate(key, settings, validateDependencies, validateInternalIndex);
             } catch (final RuntimeException ex) {
                 exceptions.add(ex);
             }
@@ -314,9 +345,27 @@ public abstract class AbstractScopedSettings extends AbstractComponent {
     }
 
     /**
-     * Validates that the setting is valid
+     * Validates that the settings is valid.
+     *
+     * @param key the key of the setting to validate
+     * @param settings the settings
+     * @param validateDependencies true if dependent settings should be validated
+     * @throws IllegalArgumentException if the setting is invalid
      */
-    void validate(String key, Settings settings, boolean validateDependencies) {
+    void validate(final String key, final Settings settings, final boolean validateDependencies) {
+        validate(key, settings, validateDependencies, false);
+    }
+
+    /**
+     * Validates that the settings is valid.
+     *
+     * @param key the key of the setting to validate
+     * @param settings the settings
+     * @param validateDependencies true if dependent settings should be validated
+     * @param validateInternalIndex true if internal index settings should be validated
+     * @throws IllegalArgumentException if the setting is invalid
+     */
+    void validate(final String key, final Settings settings, final boolean validateDependencies, final boolean validateInternalIndex) {
         Setting setting = getRaw(key);
         if (setting == null) {
             LevensteinDistance ld = new LevensteinDistance();
@@ -356,6 +405,11 @@ public abstract class AbstractScopedSettings extends AbstractComponent {
                     }
                 }
             }
+            // the only time that validateInternalIndex should be true is if this call is coming via the update settings API
+            if (validateInternalIndex && setting.getProperties().contains(Setting.Property.InternalIndex)) {
+                throw new IllegalArgumentException(
+                        "can not update internal setting [" + setting.getKey() + "]; this setting is managed via a dedicated API");
+            }
         }
         setting.get(settings);
     }
diff --git a/server/src/main/java/org/elasticsearch/common/settings/Setting.java b/server/src/main/java/org/elasticsearch/common/settings/Setting.java
index f45f4bda9c9..7f3906ff5a2 100644
--- a/server/src/main/java/org/elasticsearch/common/settings/Setting.java
+++ b/server/src/main/java/org/elasticsearch/common/settings/Setting.java
@@ -120,7 +120,13 @@ public class Setting<T> implements ToXContentObject {
          * Mark this setting as not copyable during an index resize (shrink or split). This property can only be applied to settings that
          * also have {@link Property#IndexScope}.
          */
-        NotCopyableOnResize
+        NotCopyableOnResize,
+
+        /**
+         * Indicates an index-level setting that is managed internally. Such a setting can only be added to an index on index creation but
+         * can not be updated via the update API.
+         */
+        InternalIndex
     }
 
     private final Key key;
@@ -152,14 +158,18 @@ public class Setting<T> implements ToXContentObject {
             if (propertiesAsSet.contains(Property.Dynamic) && propertiesAsSet.contains(Property.Final)) {
                 throw new IllegalArgumentException("final setting [" + key + "] cannot be dynamic");
             }
-            if (propertiesAsSet.contains(Property.NotCopyableOnResize) && propertiesAsSet.contains(Property.IndexScope) == false) {
-                throw new IllegalArgumentException(
-                        "non-index-scoped setting [" + key + "] can not have property [" + Property.NotCopyableOnResize + "]");
-            }
+            checkPropertyRequiresIndexScope(propertiesAsSet, Property.NotCopyableOnResize);
+            checkPropertyRequiresIndexScope(propertiesAsSet, Property.InternalIndex);
             this.properties = propertiesAsSet;
         }
     }
 
+    private void checkPropertyRequiresIndexScope(final EnumSet<Property> properties, final Property property) {
+        if (properties.contains(property) && properties.contains(Property.IndexScope) == false) {
+            throw new IllegalArgumentException("non-index-scoped setting [" + key + "] can not have property [" + property + "]");
+        }
+    }
+
     /**
      * Creates a new Setting instance
      * @param key the settings key for this setting.
diff --git a/server/src/test/java/org/elasticsearch/common/settings/ScopedSettingsTests.java b/server/src/test/java/org/elasticsearch/common/settings/ScopedSettingsTests.java
index f00768651f9..2376d566340 100644
--- a/server/src/test/java/org/elasticsearch/common/settings/ScopedSettingsTests.java
+++ b/server/src/test/java/org/elasticsearch/common/settings/ScopedSettingsTests.java
@@ -876,4 +876,28 @@ public class ScopedSettingsTests extends ESTestCase {
                 Settings.builder().put(currentSettings), Settings.builder(), "node"));
         assertThat(exc.getMessage(), containsString("final node setting [some.final.group.foo]"));
     }
+
+    public void testInternalIndexSettingsFailsValidation() {
+        final Setting<String> indexInternalSetting = Setting.simpleString("index.internal", Property.InternalIndex, Property.IndexScope);
+        final IndexScopedSettings indexScopedSettings =
+                new IndexScopedSettings(Settings.EMPTY, Collections.singleton(indexInternalSetting));
+        final IllegalArgumentException e = expectThrows(
+                IllegalArgumentException.class,
+                () -> {
+                    final Settings settings = Settings.builder().put("index.internal", "internal").build();
+                    indexScopedSettings.validate(settings, false, /* validateInternalIndex */ true);
+                });
+        final String message = "can not update internal setting [index.internal]; this setting is managed via a dedicated API";
+        assertThat(e, hasToString(containsString(message)));
+    }
+
+    public void testInternalIndexSettingsSkipValidation() {
+        final Setting<String> internalIndexSetting = Setting.simpleString("index.internal", Property.InternalIndex, Property.IndexScope);
+        final IndexScopedSettings indexScopedSettings = 
+                new IndexScopedSettings(Settings.EMPTY, Collections.singleton(internalIndexSetting));
+        // nothing should happen, validation should not throw an exception
+        final Settings settings = Settings.builder().put("index.internal", "internal").build();
+        indexScopedSettings.validate(settings, false, /* validateInternalIndex */ false);
+    }
+
 }
diff --git a/server/src/test/java/org/elasticsearch/common/settings/SettingTests.java b/server/src/test/java/org/elasticsearch/common/settings/SettingTests.java
index 1ab92526e31..c32037f4452 100644
--- a/server/src/test/java/org/elasticsearch/common/settings/SettingTests.java
+++ b/server/src/test/java/org/elasticsearch/common/settings/SettingTests.java
@@ -735,6 +735,13 @@ public class SettingTests extends ESTestCase {
         assertThat(e, hasToString(containsString("non-index-scoped setting [foo.bar] can not have property [NotCopyableOnResize]")));
     }
 
+    public void testRejectNonIndexScopedIndexInternalSetting() {
+        final IllegalArgumentException e = expectThrows(
+                IllegalArgumentException.class,
+                () -> Setting.simpleString("foo.bar", Property.InternalIndex));
+        assertThat(e, hasToString(containsString("non-index-scoped setting [foo.bar] can not have property [InternalIndex]")));
+    }
+
     public void testTimeValue() {
         final TimeValue random = TimeValue.parseTimeValue(randomTimeValue(), "test");
 
diff --git a/server/src/test/java/org/elasticsearch/indices/settings/UpdateSettingsIT.java b/server/src/test/java/org/elasticsearch/indices/settings/UpdateSettingsIT.java
index 51c073c607e..8093e7d38a1 100644
--- a/server/src/test/java/org/elasticsearch/indices/settings/UpdateSettingsIT.java
+++ b/server/src/test/java/org/elasticsearch/indices/settings/UpdateSettingsIT.java
@@ -19,19 +19,40 @@
 
 package org.elasticsearch.indices.settings;
 
+import org.elasticsearch.action.Action;
+import org.elasticsearch.action.ActionListener;
+import org.elasticsearch.action.ActionRequest;
+import org.elasticsearch.action.ActionRequestValidationException;
+import org.elasticsearch.action.ActionResponse;
 import org.elasticsearch.action.admin.cluster.health.ClusterHealthResponse;
 import org.elasticsearch.action.admin.indices.settings.get.GetSettingsResponse;
+import org.elasticsearch.action.support.ActionFilters;
+import org.elasticsearch.action.support.master.MasterNodeRequest;
+import org.elasticsearch.action.support.master.TransportMasterNodeAction;
+import org.elasticsearch.cluster.ClusterState;
+import org.elasticsearch.cluster.ClusterStateUpdateTask;
+import org.elasticsearch.cluster.block.ClusterBlockException;
 import org.elasticsearch.cluster.metadata.IndexMetaData;
+import org.elasticsearch.cluster.metadata.IndexNameExpressionResolver;
+import org.elasticsearch.cluster.metadata.MetaData;
+import org.elasticsearch.cluster.service.ClusterService;
 import org.elasticsearch.common.Priority;
+import org.elasticsearch.common.inject.Inject;
+import org.elasticsearch.common.io.stream.StreamInput;
+import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.settings.Setting;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.index.IndexModule;
 import org.elasticsearch.index.IndexService;
 import org.elasticsearch.index.engine.VersionConflictEngineException;
 import org.elasticsearch.indices.IndicesService;
+import org.elasticsearch.plugins.ActionPlugin;
 import org.elasticsearch.plugins.Plugin;
 import org.elasticsearch.test.ESIntegTestCase;
+import org.elasticsearch.threadpool.ThreadPool;
+import org.elasticsearch.transport.TransportService;
 
+import java.io.IOException;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
@@ -46,6 +67,7 @@ import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertBloc
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertThrows;
 import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.hasToString;
 import static org.hamcrest.Matchers.nullValue;
 
 public class UpdateSettingsIT extends ESIntegTestCase {
@@ -79,7 +101,12 @@ public class UpdateSettingsIT extends ESIntegTestCase {
 
     @Override
     protected Collection<Class<? extends Plugin>> nodePlugins() {
-        return Arrays.asList(DummySettingPlugin.class, FinalSettingPlugin.class);
+        return Arrays.asList(DummySettingPlugin.class, FinalSettingPlugin.class, InternalIndexSettingsPlugin.class);
+    }
+
+    @Override
+    protected Collection<Class<? extends Plugin>> transportClientPlugins() {
+        return Collections.singletonList(InternalIndexSettingsPlugin.class);
     }
 
     public static class DummySettingPlugin extends Plugin {
@@ -124,6 +151,151 @@ public class UpdateSettingsIT extends ESIntegTestCase {
         }
     }
 
+    public static class InternalIndexSettingsPlugin extends Plugin implements ActionPlugin {
+
+        public static final Setting<String> INDEX_INTERNAL_SETTING =
+                Setting.simpleString("index.internal", Setting.Property.IndexScope, Setting.Property.InternalIndex);
+
+        @Override
+        public List<Setting<?>> getSettings() {
+            return Collections.singletonList(INDEX_INTERNAL_SETTING);
+        }
+
+        public static class UpdateInternalIndexAction
+                extends Action<UpdateInternalIndexAction.Request, UpdateInternalIndexAction.Response> {
+
+            private static final UpdateInternalIndexAction INSTANCE = new UpdateInternalIndexAction();
+            private static final String NAME = "indices:admin/settings/update-internal-index";
+
+            public UpdateInternalIndexAction() {
+                super(NAME);
+            }
+
+            static class Request extends MasterNodeRequest<Request> {
+
+                private String index;
+                private String value;
+
+                Request() {
+
+                }
+
+                Request(final String index, final String value) {
+                    this.index = index;
+                    this.value = value;
+                }
+
+                @Override
+                public ActionRequestValidationException validate() {
+                    return null;
+                }
+
+                @Override
+                public void readFrom(final StreamInput in) throws IOException {
+                    super.readFrom(in);
+                    index = in.readString();
+                    value = in.readString();
+                }
+
+                @Override
+                public void writeTo(final StreamOutput out) throws IOException {
+                    super.writeTo(out);
+                    out.writeString(index);
+                    out.writeString(value);
+                }
+
+            }
+
+            static class Response extends ActionResponse {
+
+            }
+
+            @Override
+            public Response newResponse() {
+                return new Response();
+            }
+
+        }
+
+        public static class TransportUpdateInternalIndexAction
+                extends TransportMasterNodeAction<UpdateInternalIndexAction.Request, UpdateInternalIndexAction.Response> {
+
+            @Inject
+            public TransportUpdateInternalIndexAction(
+                    final Settings settings,
+                    final TransportService transportService,
+                    final ClusterService clusterService,
+                    final ThreadPool threadPool,
+                    final ActionFilters actionFilters,
+                    final IndexNameExpressionResolver indexNameExpressionResolver) {
+                super(
+                        settings,
+                        UpdateInternalIndexAction.NAME,
+                        transportService,
+                        clusterService,
+                        threadPool,
+                        actionFilters,
+                        indexNameExpressionResolver,
+                        UpdateInternalIndexAction.Request::new);
+            }
+
+            @Override
+            protected String executor() {
+                return ThreadPool.Names.SAME;
+            }
+
+            @Override
+            protected UpdateInternalIndexAction.Response newResponse() {
+                return new UpdateInternalIndexAction.Response();
+            }
+
+            @Override
+            protected void masterOperation(
+                    final UpdateInternalIndexAction.Request request,
+                    final ClusterState state,
+                    final ActionListener<UpdateInternalIndexAction.Response> listener) throws Exception {
+                clusterService.submitStateUpdateTask("update-index-internal", new ClusterStateUpdateTask() {
+                    @Override
+                    public ClusterState execute(final ClusterState currentState) throws Exception {
+                        final MetaData.Builder builder = MetaData.builder(currentState.metaData());
+                        final IndexMetaData.Builder imdBuilder = IndexMetaData.builder(currentState.metaData().index(request.index));
+                        final Settings.Builder settingsBuilder =
+                                Settings.builder()
+                                        .put(currentState.metaData().index(request.index).getSettings())
+                                        .put("index.internal", request.value);
+                        imdBuilder.settings(settingsBuilder);
+                        builder.put(imdBuilder.build(), true);
+                        return ClusterState.builder(currentState).metaData(builder).build();
+                    }
+
+                    @Override
+                    public void clusterStateProcessed(final String source, final ClusterState oldState, final ClusterState newState) {
+                        listener.onResponse(new UpdateInternalIndexAction.Response());
+                    }
+
+                    @Override
+                    public void onFailure(final String source, final Exception e) {
+                        listener.onFailure(e);
+                    }
+
+                });
+            }
+
+            @Override
+            protected ClusterBlockException checkBlock(UpdateInternalIndexAction.Request request, ClusterState state) {
+                return null;
+            }
+
+        }
+
+        @Override
+        public List<ActionHandler<? extends ActionRequest, ? extends ActionResponse>> getActions() {
+            return Collections.singletonList(
+                    new ActionHandler<>(UpdateInternalIndexAction.INSTANCE, TransportUpdateInternalIndexAction.class));
+        }
+
+    }
+
     public void testUpdateDependentClusterSettings() {
         IllegalArgumentException iae = expectThrows(IllegalArgumentException.class, () ->
             client().admin().cluster().prepareUpdateSettings().setPersistentSettings(Settings.builder()
@@ -474,4 +646,35 @@ public class UpdateSettingsIT extends ESIntegTestCase {
         }
     }
 
+    public void testUpdateInternalIndexSettingViaSettingsAPI() {
+        final Settings settings = Settings.builder().put("index.internal", "internal").build();
+        createIndex("test", settings);
+        final GetSettingsResponse response = client().admin().indices().prepareGetSettings("test").get();
+        assertThat(response.getSetting("test", "index.internal"), equalTo("internal"));
+        // we can not update the setting via the update settings API
+        final IllegalArgumentException e = expectThrows(IllegalArgumentException.class,
+                () -> client().admin()
+                        .indices()
+                        .prepareUpdateSettings("test")
+                        .setSettings(Settings.builder().put("index.internal", "internal-update"))
+                        .get());
+        final String message = "can not update internal setting [index.internal]; this setting is managed via a dedicated API";
+        assertThat(e, hasToString(containsString(message)));
+        final GetSettingsResponse responseAfterAttemptedUpdate = client().admin().indices().prepareGetSettings("test").get();
+        assertThat(responseAfterAttemptedUpdate.getSetting("test", "index.internal"), equalTo("internal"));
+    }
+
+    public void testUpdateInternalIndexSettingViaDedicatedAPI() {
+        final Settings settings = Settings.builder().put("index.internal", "internal").build();
+        createIndex("test", settings);
+        final GetSettingsResponse response = client().admin().indices().prepareGetSettings("test").get();
+        assertThat(response.getSetting("test", "index.internal"), equalTo("internal"));
+        client().execute(
+                InternalIndexSettingsPlugin.UpdateInternalIndexAction.INSTANCE,
+                new InternalIndexSettingsPlugin.UpdateInternalIndexAction.Request("test", "internal-update"))
+                .actionGet();
+        final GetSettingsResponse responseAfterUpdate = client().admin().indices().prepareGetSettings("test").get();
+        assertThat(responseAfterUpdate.getSetting("test", "index.internal"), equalTo("internal-update"));
+    }
+
 }
diff --git a/test/framework/src/main/java/org/elasticsearch/test/rest/yaml/Features.java b/test/framework/src/main/java/org/elasticsearch/test/rest/yaml/Features.java
index bb885d3f181..757fc2218d5 100644
--- a/test/framework/src/main/java/org/elasticsearch/test/rest/yaml/Features.java
+++ b/test/framework/src/main/java/org/elasticsearch/test/rest/yaml/Features.java
@@ -19,8 +19,6 @@
 
 package org.elasticsearch.test.rest.yaml;
 
-import org.elasticsearch.test.ESIntegTestCase;
-
 import java.util.Arrays;
 import java.util.List;
 
@@ -56,9 +54,6 @@ public final class Features {
      */
     public static boolean areAllSupported(List<String> features) {
         for (String feature : features) {
-            if ("requires_replica".equals(feature) && ESIntegTestCase.cluster().numDataNodes() >= 2) {
-                continue;
-            }
             if (!SUPPORTED.contains(feature)) {
                 return false;
             }
diff --git a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/rollup/job/MetricConfig.java b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/rollup/job/MetricConfig.java
index f26c67935ed..67b83646c42 100644
--- a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/rollup/job/MetricConfig.java
+++ b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/rollup/job/MetricConfig.java
@@ -12,7 +12,7 @@ import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
-import org.elasticsearch.common.xcontent.ConstructingObjectParser;
+import org.elasticsearch.common.xcontent.ObjectParser;
 import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.index.mapper.NumberFieldMapper;
@@ -75,12 +75,11 @@ public class MetricConfig implements Writeable, ToXContentFragment {
         MAPPER_TYPES = types;
     }
 
-    public static final ConstructingObjectParser<MetricConfig, Void> PARSER = new ConstructingObjectParser<>(
-            NAME, a -> new MetricConfig((String)a[0], (List<String>) a[1]));
+    public static final ObjectParser<MetricConfig.Builder, Void> PARSER = new ObjectParser<>(NAME, MetricConfig.Builder::new);
 
     static {
-        PARSER.declareString(ConstructingObjectParser.constructorArg(), FIELD);
-        PARSER.declareStringArray(ConstructingObjectParser.constructorArg(), METRICS);
+        PARSER.declareString(MetricConfig.Builder::setField, FIELD);
+        PARSER.declareStringArray(MetricConfig.Builder::setMetrics, METRICS);
     }
 
     MetricConfig(String name, List<String> metrics) {
@@ -257,4 +256,4 @@ public class MetricConfig implements Writeable, ToXContentFragment {
             return new MetricConfig(field, metrics);
         }
     }
-}
\ No newline at end of file
+}
diff --git a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/rollup/job/RollupJobConfig.java b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/rollup/job/RollupJobConfig.java
index 3818ebcf447..422ecdd5fd9 100644
--- a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/rollup/job/RollupJobConfig.java
+++ b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/rollup/job/RollupJobConfig.java
@@ -63,7 +63,7 @@ public class RollupJobConfig implements NamedWriteable, ToXContentObject {
     static {
         PARSER.declareString(RollupJobConfig.Builder::setId, RollupField.ID);
         PARSER.declareObject(RollupJobConfig.Builder::setGroupConfig, (p, c) -> GroupConfig.PARSER.apply(p,c).build(), GROUPS);
-        PARSER.declareObjectArray(RollupJobConfig.Builder::setMetricsConfig, MetricConfig.PARSER, METRICS);
+        PARSER.declareObjectArray(RollupJobConfig.Builder::setMetricsConfig, (p, c) -> MetricConfig.PARSER.apply(p, c).build(), METRICS);
         PARSER.declareString((params, val) ->
                 params.setTimeout(TimeValue.parseTimeValue(val, TIMEOUT.getPreferredName())), TIMEOUT);
         PARSER.declareString(RollupJobConfig.Builder::setIndexPattern, INDEX_PATTERN);
diff --git a/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ml/datafeed/DatafeedConfigTests.java b/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ml/datafeed/DatafeedConfigTests.java
index 6aa987fc0e9..d59ef16dfdf 100644
--- a/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ml/datafeed/DatafeedConfigTests.java
+++ b/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ml/datafeed/DatafeedConfigTests.java
@@ -40,7 +40,6 @@ import org.joda.time.DateTimeZone;
 
 import java.io.IOException;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 import java.util.TimeZone;
@@ -193,11 +192,11 @@ public class DatafeedConfigTests extends AbstractSerializingTestCase<DatafeedCon
 
     public void testDefaultQueryDelay() {
         DatafeedConfig.Builder feedBuilder1 = new DatafeedConfig.Builder("datafeed1", "job1");
-        feedBuilder1.setIndices(Arrays.asList("foo"));
+        feedBuilder1.setIndices(Collections.singletonList("foo"));
         DatafeedConfig.Builder feedBuilder2 = new DatafeedConfig.Builder("datafeed2", "job1");
-        feedBuilder2.setIndices(Arrays.asList("foo"));
+        feedBuilder2.setIndices(Collections.singletonList("foo"));
         DatafeedConfig.Builder feedBuilder3 = new DatafeedConfig.Builder("datafeed3", "job2");
-        feedBuilder3.setIndices(Arrays.asList("foo"));
+        feedBuilder3.setIndices(Collections.singletonList("foo"));
         DatafeedConfig feed1 = feedBuilder1.build();
         DatafeedConfig feed2 = feedBuilder2.build();
         DatafeedConfig feed3 = feedBuilder3.build();
@@ -208,19 +207,19 @@ public class DatafeedConfigTests extends AbstractSerializingTestCase<DatafeedCon
         assertThat(feed1.getQueryDelay(), not(equalTo(feed3.getQueryDelay())));
     }
 
-    public void testCheckValid_GivenNullIndices() throws IOException {
+    public void testCheckValid_GivenNullIndices() {
         DatafeedConfig.Builder conf = new DatafeedConfig.Builder("datafeed1", "job1");
         expectThrows(IllegalArgumentException.class, () -> conf.setIndices(null));
     }
 
-    public void testCheckValid_GivenEmptyIndices() throws IOException {
+    public void testCheckValid_GivenEmptyIndices() {
         DatafeedConfig.Builder conf = new DatafeedConfig.Builder("datafeed1", "job1");
         conf.setIndices(Collections.emptyList());
         ElasticsearchException e = ESTestCase.expectThrows(ElasticsearchException.class, conf::build);
         assertEquals(Messages.getMessage(Messages.DATAFEED_CONFIG_INVALID_OPTION_VALUE, "indices", "[]"), e.getMessage());
     }
 
-    public void testCheckValid_GivenIndicesContainsOnlyNulls() throws IOException {
+    public void testCheckValid_GivenIndicesContainsOnlyNulls() {
         List<String> indices = new ArrayList<>();
         indices.add(null);
         indices.add(null);
@@ -230,7 +229,7 @@ public class DatafeedConfigTests extends AbstractSerializingTestCase<DatafeedCon
         assertEquals(Messages.getMessage(Messages.DATAFEED_CONFIG_INVALID_OPTION_VALUE, "indices", "[null, null]"), e.getMessage());
     }
 
-    public void testCheckValid_GivenIndicesContainsOnlyEmptyStrings() throws IOException {
+    public void testCheckValid_GivenIndicesContainsOnlyEmptyStrings() {
         List<String> indices = new ArrayList<>();
         indices.add("");
         indices.add("");
@@ -240,27 +239,27 @@ public class DatafeedConfigTests extends AbstractSerializingTestCase<DatafeedCon
         assertEquals(Messages.getMessage(Messages.DATAFEED_CONFIG_INVALID_OPTION_VALUE, "indices", "[, ]"), e.getMessage());
     }
 
-    public void testCheckValid_GivenNegativeQueryDelay() throws IOException {
+    public void testCheckValid_GivenNegativeQueryDelay() {
         DatafeedConfig.Builder conf = new DatafeedConfig.Builder("datafeed1", "job1");
         IllegalArgumentException e = ESTestCase.expectThrows(IllegalArgumentException.class,
                 () -> conf.setQueryDelay(TimeValue.timeValueMillis(-10)));
         assertEquals("query_delay cannot be less than 0. Value = -10", e.getMessage());
     }
 
-    public void testCheckValid_GivenZeroFrequency() throws IOException {
+    public void testCheckValid_GivenZeroFrequency() {
         DatafeedConfig.Builder conf = new DatafeedConfig.Builder("datafeed1", "job1");
         IllegalArgumentException e = ESTestCase.expectThrows(IllegalArgumentException.class, () -> conf.setFrequency(TimeValue.ZERO));
         assertEquals("frequency cannot be less or equal than 0. Value = 0s", e.getMessage());
     }
 
-    public void testCheckValid_GivenNegativeFrequency() throws IOException {
+    public void testCheckValid_GivenNegativeFrequency() {
         DatafeedConfig.Builder conf = new DatafeedConfig.Builder("datafeed1", "job1");
         IllegalArgumentException e = ESTestCase.expectThrows(IllegalArgumentException.class,
                 () -> conf.setFrequency(TimeValue.timeValueMinutes(-1)));
         assertEquals("frequency cannot be less or equal than 0. Value = -1", e.getMessage());
     }
 
-    public void testCheckValid_GivenNegativeScrollSize() throws IOException {
+    public void testCheckValid_GivenNegativeScrollSize() {
         DatafeedConfig.Builder conf = new DatafeedConfig.Builder("datafeed1", "job1");
         ElasticsearchException e = ESTestCase.expectThrows(ElasticsearchException.class, () -> conf.setScrollSize(-1000));
         assertEquals(Messages.getMessage(Messages.DATAFEED_CONFIG_INVALID_OPTION_VALUE, "scroll_size", -1000L), e.getMessage());
@@ -414,7 +413,7 @@ public class DatafeedConfigTests extends AbstractSerializingTestCase<DatafeedCon
 
     public void testDefaultFrequency_GivenNoAggregations() {
         DatafeedConfig.Builder datafeedBuilder = new DatafeedConfig.Builder("feed", "job");
-        datafeedBuilder.setIndices(Arrays.asList("my_index"));
+        datafeedBuilder.setIndices(Collections.singletonList("my_index"));
         DatafeedConfig datafeed = datafeedBuilder.build();
 
         assertEquals(TimeValue.timeValueMinutes(1), datafeed.defaultFrequency(TimeValue.timeValueSeconds(1)));
diff --git a/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/rollup/job/MetricsConfigSerializingTests.java b/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/rollup/job/MetricsConfigSerializingTests.java
index 92a0976f532..9b330e71650 100644
--- a/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/rollup/job/MetricsConfigSerializingTests.java
+++ b/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/rollup/job/MetricsConfigSerializingTests.java
@@ -24,7 +24,7 @@ import static org.mockito.Mockito.when;
 public class MetricsConfigSerializingTests extends AbstractSerializingTestCase<MetricConfig> {
     @Override
     protected MetricConfig doParseInstance(XContentParser parser) throws IOException {
-        return MetricConfig.PARSER.apply(parser, null);
+        return MetricConfig.PARSER.apply(parser, null).build();
     }
 
     @Override
@@ -36,7 +36,7 @@ public class MetricsConfigSerializingTests extends AbstractSerializingTestCase<M
     protected MetricConfig createTestInstance() {
         return ConfigTestHelpers.getMetricConfig().build();
     }
-    
+
     public void testValidateNoMapping() throws IOException {
         ActionRequestValidationException e = new ActionRequestValidationException();
         Map<String, Map<String, FieldCapabilities>> responseMap = new HashMap<>();
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/action/TransportStartDatafeedAction.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/action/TransportStartDatafeedAction.java
index bed83ed82c1..3d261864ab4 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/action/TransportStartDatafeedAction.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/action/TransportStartDatafeedAction.java
@@ -43,10 +43,12 @@ import org.elasticsearch.persistent.PersistentTasksCustomMetaData;
 import org.elasticsearch.persistent.PersistentTasksExecutor;
 import org.elasticsearch.persistent.PersistentTasksService;
 import org.elasticsearch.xpack.ml.MachineLearning;
+import org.elasticsearch.xpack.ml.datafeed.MlRemoteLicenseChecker;
 import org.elasticsearch.xpack.ml.datafeed.DatafeedManager;
 import org.elasticsearch.xpack.ml.datafeed.DatafeedNodeSelector;
 import org.elasticsearch.xpack.ml.datafeed.extractor.DataExtractorFactory;
 
+import java.util.List;
 import java.util.Map;
 import java.util.function.Predicate;
 
@@ -111,23 +113,25 @@ public class TransportStartDatafeedAction extends TransportMasterNodeAction<Star
                                    ActionListener<StartDatafeedAction.Response> listener) {
         StartDatafeedAction.DatafeedParams params = request.getParams();
         if (licenseState.isMachineLearningAllowed()) {
-            ActionListener<PersistentTasksCustomMetaData.PersistentTask<StartDatafeedAction.DatafeedParams>> finalListener =
-                    new ActionListener<PersistentTasksCustomMetaData.PersistentTask<StartDatafeedAction.DatafeedParams>>() {
-                @Override
-                public void onResponse(PersistentTasksCustomMetaData.PersistentTask<StartDatafeedAction.DatafeedParams> persistentTask) {
-                    waitForDatafeedStarted(persistentTask.getId(), params, listener);
-                }
 
-                @Override
-                public void onFailure(Exception e) {
-                    if (e instanceof ResourceAlreadyExistsException) {
-                        logger.debug("datafeed already started", e);
-                        e = new ElasticsearchStatusException("cannot start datafeed [" + params.getDatafeedId() +
-                                "] because it has already been started", RestStatus.CONFLICT);
-                    }
-                    listener.onFailure(e);
-                }
-            };
+            ActionListener<PersistentTasksCustomMetaData.PersistentTask<StartDatafeedAction.DatafeedParams>> waitForTaskListener =
+                    new ActionListener<PersistentTasksCustomMetaData.PersistentTask<StartDatafeedAction.DatafeedParams>>() {
+                        @Override
+                        public void onResponse(PersistentTasksCustomMetaData.PersistentTask<StartDatafeedAction.DatafeedParams>
+                                                       persistentTask) {
+                            waitForDatafeedStarted(persistentTask.getId(), params, listener);
+                        }
+
+                        @Override
+                        public void onFailure(Exception e) {
+                            if (e instanceof ResourceAlreadyExistsException) {
+                                logger.debug("datafeed already started", e);
+                                e = new ElasticsearchStatusException("cannot start datafeed [" + params.getDatafeedId() +
+                                        "] because it has already been started", RestStatus.CONFLICT);
+                            }
+                            listener.onFailure(e);
+                        }
+                    };
 
             // Verify data extractor factory can be created, then start persistent task
             MlMetadata mlMetadata = MlMetadata.getMlMetadata(state);
@@ -135,16 +139,39 @@ public class TransportStartDatafeedAction extends TransportMasterNodeAction<Star
             validate(params.getDatafeedId(), mlMetadata, tasks);
             DatafeedConfig datafeed = mlMetadata.getDatafeed(params.getDatafeedId());
             Job job = mlMetadata.getJobs().get(datafeed.getJobId());
-            DataExtractorFactory.create(client, datafeed, job, ActionListener.wrap(
-                    dataExtractorFactory ->
-                            persistentTasksService.sendStartRequest(MLMetadataField.datafeedTaskId(params.getDatafeedId()),
-                            StartDatafeedAction.TASK_NAME, params, finalListener)
-                    , listener::onFailure));
+
+            if (MlRemoteLicenseChecker.containsRemoteIndex(datafeed.getIndices())) {
+                MlRemoteLicenseChecker remoteLicenseChecker = new MlRemoteLicenseChecker(client);
+                remoteLicenseChecker.checkRemoteClusterLicenses(MlRemoteLicenseChecker.remoteClusterNames(datafeed.getIndices()),
+                        ActionListener.wrap(
+                                response -> {
+                                    if (response.isViolated()) {
+                                        listener.onFailure(createUnlicensedError(datafeed.getId(), response));
+                                    } else {
+                                        createDataExtractor(job, datafeed, params, waitForTaskListener);
+                                    }
+                                },
+                                e -> listener.onFailure(createUnknownLicenseError(datafeed.getId(),
+                                        MlRemoteLicenseChecker.remoteIndices(datafeed.getIndices()), e))
+                        ));
+            } else {
+                createDataExtractor(job, datafeed, params, waitForTaskListener);
+            }
         } else {
             listener.onFailure(LicenseUtils.newComplianceException(XPackField.MACHINE_LEARNING));
         }
     }
 
+    private void createDataExtractor(Job job, DatafeedConfig datafeed, StartDatafeedAction.DatafeedParams params,
+                                     ActionListener<PersistentTasksCustomMetaData.PersistentTask<StartDatafeedAction.DatafeedParams>>
+                                             listener) {
+        DataExtractorFactory.create(client, datafeed, job, ActionListener.wrap(
+                dataExtractorFactory ->
+                        persistentTasksService.sendStartRequest(MLMetadataField.datafeedTaskId(params.getDatafeedId()),
+                                StartDatafeedAction.TASK_NAME, params, listener)
+                , listener::onFailure));
+    }
+
     @Override
     protected ClusterBlockException checkBlock(StartDatafeedAction.Request request, ClusterState state) {
         // We only delegate here to PersistentTasksService, but if there is a metadata writeblock,
@@ -158,28 +185,29 @@ public class TransportStartDatafeedAction extends TransportMasterNodeAction<Star
         DatafeedPredicate predicate = new DatafeedPredicate();
         persistentTasksService.waitForPersistentTaskCondition(taskId, predicate, params.getTimeout(),
                 new PersistentTasksService.WaitForPersistentTaskListener<StartDatafeedAction.DatafeedParams>() {
-            @Override
-            public void onResponse(PersistentTasksCustomMetaData.PersistentTask<StartDatafeedAction.DatafeedParams> persistentTask) {
-                if (predicate.exception != null) {
-                    // We want to return to the caller without leaving an unassigned persistent task, to match
-                    // what would have happened if the error had been detected in the "fast fail" validation
-                    cancelDatafeedStart(persistentTask, predicate.exception, listener);
-                } else {
-                    listener.onResponse(new StartDatafeedAction.Response(true));
-                }
-            }
+                    @Override
+                    public void onResponse(PersistentTasksCustomMetaData.PersistentTask<StartDatafeedAction.DatafeedParams>
+                                                   persistentTask) {
+                        if (predicate.exception != null) {
+                            // We want to return to the caller without leaving an unassigned persistent task, to match
+                            // what would have happened if the error had been detected in the "fast fail" validation
+                            cancelDatafeedStart(persistentTask, predicate.exception, listener);
+                        } else {
+                            listener.onResponse(new StartDatafeedAction.Response(true));
+                        }
+                    }
 
-            @Override
-            public void onFailure(Exception e) {
-                listener.onFailure(e);
-            }
+                    @Override
+                    public void onFailure(Exception e) {
+                        listener.onFailure(e);
+                    }
 
-            @Override
-            public void onTimeout(TimeValue timeout) {
-                listener.onFailure(new ElasticsearchException("Starting datafeed ["
-                        + params.getDatafeedId() + "] timed out after [" + timeout + "]"));
-            }
-        });
+                    @Override
+                    public void onTimeout(TimeValue timeout) {
+                        listener.onFailure(new ElasticsearchException("Starting datafeed ["
+                                + params.getDatafeedId() + "] timed out after [" + timeout + "]"));
+                    }
+                });
     }
 
     private void cancelDatafeedStart(PersistentTasksCustomMetaData.PersistentTask<StartDatafeedAction.DatafeedParams> persistentTask,
@@ -203,6 +231,25 @@ public class TransportStartDatafeedAction extends TransportMasterNodeAction<Star
         );
     }
 
+    private ElasticsearchStatusException createUnlicensedError(String datafeedId,
+                                                               MlRemoteLicenseChecker.LicenseViolation licenseViolation) {
+        String message = "Cannot start datafeed [" + datafeedId + "] as it is configured to use "
+                + "indices on a remote cluster [" + licenseViolation.get().getClusterName()
+                + "] that is not licensed for Machine Learning. "
+                + MlRemoteLicenseChecker.buildErrorMessage(licenseViolation.get());
+
+        return new ElasticsearchStatusException(message, RestStatus.BAD_REQUEST);
+    }
+
+    private ElasticsearchStatusException createUnknownLicenseError(String datafeedId, List<String> remoteIndices,
+                                                                   Exception cause) {
+        String message = "Cannot start datafeed [" + datafeedId + "] as it is configured to use"
+                + " indices on a remote cluster " + remoteIndices
+                + " but the license type could not be verified";
+
+        return new ElasticsearchStatusException(message, RestStatus.BAD_REQUEST, new Exception(cause.getMessage()));
+    }
+
     public static class StartDatafeedPersistentTasksExecutor extends PersistentTasksExecutor<StartDatafeedAction.DatafeedParams> {
         private final DatafeedManager datafeedManager;
         private final IndexNameExpressionResolver resolver;
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/datafeed/DatafeedNodeSelector.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/datafeed/DatafeedNodeSelector.java
index 37f9715d094..0eb57ab79be 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/datafeed/DatafeedNodeSelector.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/datafeed/DatafeedNodeSelector.java
@@ -91,7 +91,7 @@ public class DatafeedNodeSelector {
         List<String> indices = datafeed.getIndices();
         for (String index : indices) {
 
-            if (isRemoteIndex(index)) {
+            if (MlRemoteLicenseChecker.isRemoteIndex(index)) {
                 // We cannot verify remote indices
                 continue;
             }
@@ -122,10 +122,6 @@ public class DatafeedNodeSelector {
         return null;
     }
 
-    private boolean isRemoteIndex(String index) {
-        return index.indexOf(':') != -1;
-    }
-
     private static class AssignmentFailure {
         private final String reason;
         private final boolean isCriticalForTaskCreation;
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/datafeed/MlRemoteLicenseChecker.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/datafeed/MlRemoteLicenseChecker.java
new file mode 100644
index 00000000000..b55713f6d0a
--- /dev/null
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/datafeed/MlRemoteLicenseChecker.java
@@ -0,0 +1,192 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+
+package org.elasticsearch.xpack.ml.datafeed;
+
+import org.elasticsearch.ElasticsearchException;
+import org.elasticsearch.action.ActionListener;
+import org.elasticsearch.client.Client;
+import org.elasticsearch.common.Nullable;
+import org.elasticsearch.common.Strings;
+import org.elasticsearch.common.util.concurrent.ThreadContext;
+import org.elasticsearch.license.License;
+import org.elasticsearch.license.XPackInfoResponse;
+import org.elasticsearch.transport.ActionNotFoundTransportException;
+import org.elasticsearch.transport.RemoteClusterAware;
+import org.elasticsearch.xpack.core.action.XPackInfoAction;
+import org.elasticsearch.xpack.core.action.XPackInfoRequest;
+
+import java.util.EnumSet;
+import java.util.Iterator;
+import java.util.List;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.stream.Collectors;
+
+/**
+ * ML datafeeds can use cross cluster search to access data in a remote cluster.
+ * The remote cluster should be licenced for ML this class performs that check
+ * using the _xpack (info) endpoint.
+ */
+public class MlRemoteLicenseChecker {
+
+    private final Client client;
+
+    public static class RemoteClusterLicenseInfo {
+        private final String clusterName;
+        private final XPackInfoResponse.LicenseInfo licenseInfo;
+
+        RemoteClusterLicenseInfo(String clusterName, XPackInfoResponse.LicenseInfo licenseInfo) {
+            this.clusterName = clusterName;
+            this.licenseInfo = licenseInfo;
+        }
+
+        public String getClusterName() {
+            return clusterName;
+        }
+
+        public XPackInfoResponse.LicenseInfo getLicenseInfo() {
+            return licenseInfo;
+        }
+    }
+
+    public class LicenseViolation {
+        private final RemoteClusterLicenseInfo licenseInfo;
+
+        private LicenseViolation(@Nullable RemoteClusterLicenseInfo licenseInfo) {
+            this.licenseInfo = licenseInfo;
+        }
+
+        public boolean isViolated() {
+            return licenseInfo != null;
+        }
+
+        public RemoteClusterLicenseInfo get() {
+            return licenseInfo;
+        }
+    }
+
+    public MlRemoteLicenseChecker(Client client) {
+        this.client = client;
+    }
+
+    /**
+     * Check each cluster is licensed for ML.
+     * This function evaluates lazily and will terminate when the first cluster
+     * that is not licensed is found or an error occurs.
+     *
+     * @param clusterNames List of remote cluster names
+     * @param listener Response listener
+     */
+    public void checkRemoteClusterLicenses(List<String> clusterNames, ActionListener<LicenseViolation> listener) {
+        final Iterator<String> itr = clusterNames.iterator();
+        if (itr.hasNext() == false) {
+            listener.onResponse(new LicenseViolation(null));
+            return;
+        }
+
+        final AtomicReference<String> clusterName = new AtomicReference<>(itr.next());
+
+        ActionListener<XPackInfoResponse> infoListener = new ActionListener<XPackInfoResponse>() {
+            @Override
+            public void onResponse(XPackInfoResponse xPackInfoResponse) {
+                if (licenseSupportsML(xPackInfoResponse.getLicenseInfo()) == false) {
+                    listener.onResponse(new LicenseViolation(
+                            new RemoteClusterLicenseInfo(clusterName.get(), xPackInfoResponse.getLicenseInfo())));
+                    return;
+                }
+
+                if (itr.hasNext()) {
+                    clusterName.set(itr.next());
+                    remoteClusterLicense(clusterName.get(), this);
+                } else {
+                    listener.onResponse(new LicenseViolation(null));
+                }
+            }
+
+            @Override
+            public void onFailure(Exception e) {
+                String message = "Could not determine the X-Pack licence type for cluster [" + clusterName.get() + "]";
+                if (e instanceof ActionNotFoundTransportException) {
+                    // This is likely to be because x-pack is not installed in the target cluster
+                    message += ". Is X-Pack installed on the target cluster?";
+                }
+                listener.onFailure(new ElasticsearchException(message, e));
+            }
+        };
+
+        remoteClusterLicense(clusterName.get(), infoListener);
+    }
+
+    private void remoteClusterLicense(String clusterName, ActionListener<XPackInfoResponse> listener) {
+        Client remoteClusterClient = client.getRemoteClusterClient(clusterName);
+        ThreadContext threadContext = remoteClusterClient.threadPool().getThreadContext();
+        try (ThreadContext.StoredContext ignore = threadContext.stashContext()) {
+            // we stash any context here since this is an internal execution and should not leak any
+            // existing context information.
+            threadContext.markAsSystemContext();
+
+            XPackInfoRequest request = new XPackInfoRequest();
+            request.setCategories(EnumSet.of(XPackInfoRequest.Category.LICENSE));
+            remoteClusterClient.execute(XPackInfoAction.INSTANCE, request, listener);
+        }
+    }
+
+    static boolean licenseSupportsML(XPackInfoResponse.LicenseInfo licenseInfo) {
+        License.OperationMode mode = License.OperationMode.resolve(licenseInfo.getMode());
+        return licenseInfo.getStatus() == License.Status.ACTIVE &&
+                (mode == License.OperationMode.PLATINUM || mode == License.OperationMode.TRIAL);
+    }
+
+    public static boolean isRemoteIndex(String index) {
+        return index.indexOf(RemoteClusterAware.REMOTE_CLUSTER_INDEX_SEPARATOR) != -1;
+    }
+
+    public static boolean containsRemoteIndex(List<String> indices) {
+        return indices.stream().anyMatch(MlRemoteLicenseChecker::isRemoteIndex);
+    }
+
+    /**
+     * Get any remote indices used in cross cluster search.
+     * Remote indices are of the form {@code cluster_name:index_name}
+     * @return List of remote cluster indices
+     */
+    public static List<String> remoteIndices(List<String> indices) {
+        return indices.stream().filter(MlRemoteLicenseChecker::isRemoteIndex).collect(Collectors.toList());
+    }
+
+    /**
+     * Extract the list of remote cluster names from the list of indices.
+     * @param indices List of indices. Remote cluster indices are prefixed
+     *                with {@code cluster-name:}
+     * @return Every cluster name found in {@code indices}
+     */
+    public static List<String> remoteClusterNames(List<String> indices) {
+        return indices.stream()
+                .filter(MlRemoteLicenseChecker::isRemoteIndex)
+                .map(index -> index.substring(0, index.indexOf(RemoteClusterAware.REMOTE_CLUSTER_INDEX_SEPARATOR)))
+                .distinct()
+                .collect(Collectors.toList());
+    }
+
+    public static String buildErrorMessage(RemoteClusterLicenseInfo clusterLicenseInfo) {
+        StringBuilder error = new StringBuilder();
+        if (clusterLicenseInfo.licenseInfo.getStatus() != License.Status.ACTIVE) {
+            error.append("The license on cluster [").append(clusterLicenseInfo.clusterName)
+                    .append("] is not active. ");
+        } else {
+            License.OperationMode mode = License.OperationMode.resolve(clusterLicenseInfo.licenseInfo.getMode());
+            if (mode != License.OperationMode.PLATINUM && mode != License.OperationMode.TRIAL) {
+                error.append("The license mode [").append(mode)
+                        .append("] on cluster [")
+                        .append(clusterLicenseInfo.clusterName)
+                        .append("] does not enable Machine Learning. ");
+            }
+        }
+
+        error.append(Strings.toString(clusterLicenseInfo.licenseInfo));
+        return error.toString();
+    }
+}
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/process/autodetect/AutodetectProcess.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/process/autodetect/AutodetectProcess.java
index 049880b1ac2..21be815d561 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/process/autodetect/AutodetectProcess.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/process/autodetect/AutodetectProcess.java
@@ -117,7 +117,7 @@ public interface AutodetectProcess extends Closeable {
 
     /**
      * Ask the job to start persisting model state in the background
-     * @throws IOException
+     * @throws IOException If writing the request fails
      */
     void persistJob() throws IOException;
 
diff --git a/x-pack/plugin/ml/src/test/java/org/elasticsearch/xpack/ml/datafeed/MlRemoteLicenseCheckerTests.java b/x-pack/plugin/ml/src/test/java/org/elasticsearch/xpack/ml/datafeed/MlRemoteLicenseCheckerTests.java
new file mode 100644
index 00000000000..47d4d30a7c6
--- /dev/null
+++ b/x-pack/plugin/ml/src/test/java/org/elasticsearch/xpack/ml/datafeed/MlRemoteLicenseCheckerTests.java
@@ -0,0 +1,200 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+
+package org.elasticsearch.xpack.ml.datafeed;
+
+import org.elasticsearch.action.ActionListener;
+import org.elasticsearch.client.Client;
+import org.elasticsearch.common.Strings;
+import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.common.util.concurrent.ThreadContext;
+import org.elasticsearch.license.License;
+import org.elasticsearch.license.XPackInfoResponse;
+import org.elasticsearch.test.ESTestCase;
+import org.elasticsearch.threadpool.ThreadPool;
+import org.elasticsearch.xpack.core.action.XPackInfoAction;
+import org.elasticsearch.xpack.core.ml.datafeed.DatafeedConfig;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicReference;
+
+import static org.hamcrest.Matchers.contains;
+import static org.hamcrest.Matchers.containsInAnyOrder;
+import static org.hamcrest.Matchers.empty;
+import static org.hamcrest.Matchers.is;
+import static org.mockito.Matchers.any;
+import static org.mockito.Matchers.anyString;
+import static org.mockito.Matchers.same;
+import static org.mockito.Mockito.doAnswer;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+public class MlRemoteLicenseCheckerTests extends ESTestCase {
+
+    public void testIsRemoteIndex() {
+        List<String> indices = Arrays.asList("local-index1", "local-index2");
+        assertFalse(MlRemoteLicenseChecker.containsRemoteIndex(indices));
+        indices = Arrays.asList("local-index1", "remote-cluster:remote-index2");
+        assertTrue(MlRemoteLicenseChecker.containsRemoteIndex(indices));
+    }
+
+    public void testRemoteIndices() {
+        List<String> indices = Collections.singletonList("local-index");
+        assertThat(MlRemoteLicenseChecker.remoteIndices(indices), is(empty()));
+        indices = Arrays.asList("local-index", "remote-cluster:index1", "local-index2", "remote-cluster2:index1");
+        assertThat(MlRemoteLicenseChecker.remoteIndices(indices), containsInAnyOrder("remote-cluster:index1", "remote-cluster2:index1"));
+    }
+
+    public void testRemoteClusterNames() {
+        List<String> indices = Arrays.asList("local-index1", "local-index2");
+        assertThat(MlRemoteLicenseChecker.remoteClusterNames(indices), empty());
+        indices = Arrays.asList("local-index1", "remote-cluster1:remote-index2");
+        assertThat(MlRemoteLicenseChecker.remoteClusterNames(indices), contains("remote-cluster1"));
+        indices = Arrays.asList("remote-cluster1:index2", "index1", "remote-cluster2:index1");
+        assertThat(MlRemoteLicenseChecker.remoteClusterNames(indices), contains("remote-cluster1", "remote-cluster2"));
+        indices = Arrays.asList("remote-cluster1:index2", "index1", "remote-cluster2:index1", "remote-cluster2:index2");
+        assertThat(MlRemoteLicenseChecker.remoteClusterNames(indices), contains("remote-cluster1", "remote-cluster2"));
+    }
+
+    public void testLicenseSupportsML() {
+        XPackInfoResponse.LicenseInfo licenseInfo = new XPackInfoResponse.LicenseInfo("uid", "trial", "trial",
+                License.Status.ACTIVE, randomNonNegativeLong());
+        assertTrue(MlRemoteLicenseChecker.licenseSupportsML(licenseInfo));
+
+        licenseInfo = new XPackInfoResponse.LicenseInfo("uid", "trial", "trial", License.Status.EXPIRED, randomNonNegativeLong());
+        assertFalse(MlRemoteLicenseChecker.licenseSupportsML(licenseInfo));
+
+        licenseInfo = new XPackInfoResponse.LicenseInfo("uid", "GOLD", "GOLD", License.Status.ACTIVE, randomNonNegativeLong());
+        assertFalse(MlRemoteLicenseChecker.licenseSupportsML(licenseInfo));
+
+        licenseInfo = new XPackInfoResponse.LicenseInfo("uid", "PLATINUM", "PLATINUM", License.Status.ACTIVE, randomNonNegativeLong());
+        assertTrue(MlRemoteLicenseChecker.licenseSupportsML(licenseInfo));
+    }
+
+    public void testCheckRemoteClusterLicenses_givenValidLicenses() {
+        final AtomicInteger index = new AtomicInteger(0);
+        final List<XPackInfoResponse> responses = new ArrayList<>();
+
+        Client client = createMockClient();
+        doAnswer(invocationMock -> {
+            @SuppressWarnings("raw_types")
+            ActionListener listener = (ActionListener) invocationMock.getArguments()[2];
+            listener.onResponse(responses.get(index.getAndIncrement()));
+            return null;
+        }).when(client).execute(same(XPackInfoAction.INSTANCE), any(), any());
+
+
+        List<String> remoteClusterNames = Arrays.asList("valid1", "valid2", "valid3");
+        responses.add(new XPackInfoResponse(null, createPlatinumLicenseResponse(), null));
+        responses.add(new XPackInfoResponse(null, createPlatinumLicenseResponse(), null));
+        responses.add(new XPackInfoResponse(null, createPlatinumLicenseResponse(), null));
+
+        MlRemoteLicenseChecker licenseChecker = new MlRemoteLicenseChecker(client);
+        AtomicReference<MlRemoteLicenseChecker.LicenseViolation> licCheckResponse = new AtomicReference<>();
+
+        licenseChecker.checkRemoteClusterLicenses(remoteClusterNames,
+                new ActionListener<MlRemoteLicenseChecker.LicenseViolation>() {
+            @Override
+            public void onResponse(MlRemoteLicenseChecker.LicenseViolation response) {
+                licCheckResponse.set(response);
+            }
+
+            @Override
+            public void onFailure(Exception e) {
+                fail(e.getMessage());
+            }
+        });
+
+        verify(client, times(3)).execute(same(XPackInfoAction.INSTANCE), any(), any());
+        assertNotNull(licCheckResponse.get());
+        assertFalse(licCheckResponse.get().isViolated());
+        assertNull(licCheckResponse.get().get());
+    }
+
+    public void testCheckRemoteClusterLicenses_givenInvalidLicense() {
+        final AtomicInteger index = new AtomicInteger(0);
+        List<String> remoteClusterNames = Arrays.asList("good", "cluster-with-basic-license", "good2");
+        final List<XPackInfoResponse> responses = new ArrayList<>();
+        responses.add(new XPackInfoResponse(null, createPlatinumLicenseResponse(), null));
+        responses.add(new XPackInfoResponse(null, createBasicLicenseResponse(), null));
+        responses.add(new XPackInfoResponse(null, createPlatinumLicenseResponse(), null));
+
+        Client client = createMockClient();
+        doAnswer(invocationMock -> {
+            @SuppressWarnings("raw_types")
+            ActionListener listener = (ActionListener) invocationMock.getArguments()[2];
+            listener.onResponse(responses.get(index.getAndIncrement()));
+            return null;
+        }).when(client).execute(same(XPackInfoAction.INSTANCE), any(), any());
+
+        MlRemoteLicenseChecker licenseChecker = new MlRemoteLicenseChecker(client);
+        AtomicReference<MlRemoteLicenseChecker.LicenseViolation> licCheckResponse = new AtomicReference<>();
+
+        licenseChecker.checkRemoteClusterLicenses(remoteClusterNames,
+                new ActionListener<MlRemoteLicenseChecker.LicenseViolation>() {
+            @Override
+            public void onResponse(MlRemoteLicenseChecker.LicenseViolation response) {
+                licCheckResponse.set(response);
+            }
+
+            @Override
+            public void onFailure(Exception e) {
+                fail(e.getMessage());
+            }
+        });
+
+        verify(client, times(2)).execute(same(XPackInfoAction.INSTANCE), any(), any());
+        assertNotNull(licCheckResponse.get());
+        assertTrue(licCheckResponse.get().isViolated());
+        assertEquals("cluster-with-basic-license", licCheckResponse.get().get().getClusterName());
+        assertEquals("BASIC", licCheckResponse.get().get().getLicenseInfo().getType());
+    }
+
+    public void testBuildErrorMessage() {
+        XPackInfoResponse.LicenseInfo platinumLicence = createPlatinumLicenseResponse();
+        MlRemoteLicenseChecker.RemoteClusterLicenseInfo info =
+                new MlRemoteLicenseChecker.RemoteClusterLicenseInfo("platinum-cluster", platinumLicence);
+        assertEquals(Strings.toString(platinumLicence), MlRemoteLicenseChecker.buildErrorMessage(info));
+
+        XPackInfoResponse.LicenseInfo basicLicense = createBasicLicenseResponse();
+        info = new MlRemoteLicenseChecker.RemoteClusterLicenseInfo("basic-cluster", basicLicense);
+        String expected = "The license mode [BASIC] on cluster [basic-cluster] does not enable Machine Learning. "
+                + Strings.toString(basicLicense);
+        assertEquals(expected, MlRemoteLicenseChecker.buildErrorMessage(info));
+
+        XPackInfoResponse.LicenseInfo expiredLicense = createExpiredLicenseResponse();
+        info = new MlRemoteLicenseChecker.RemoteClusterLicenseInfo("expired-cluster", expiredLicense);
+        expected = "The license on cluster [expired-cluster] is not active. " + Strings.toString(expiredLicense);
+        assertEquals(expected, MlRemoteLicenseChecker.buildErrorMessage(info));
+    }
+
+    private Client createMockClient() {
+        Client client = mock(Client.class);
+        ThreadPool threadPool = mock(ThreadPool.class);
+        when(client.threadPool()).thenReturn(threadPool);
+        when(threadPool.getThreadContext()).thenReturn(new ThreadContext(Settings.EMPTY));
+        when(client.getRemoteClusterClient(anyString())).thenReturn(client);
+        return client;
+    }
+
+    private XPackInfoResponse.LicenseInfo createPlatinumLicenseResponse() {
+        return new XPackInfoResponse.LicenseInfo("uid", "PLATINUM", "PLATINUM", License.Status.ACTIVE, randomNonNegativeLong());
+    }
+
+    private XPackInfoResponse.LicenseInfo createBasicLicenseResponse() {
+        return new XPackInfoResponse.LicenseInfo("uid", "BASIC", "BASIC", License.Status.ACTIVE, randomNonNegativeLong());
+    }
+
+    private XPackInfoResponse.LicenseInfo createExpiredLicenseResponse() {
+        return new XPackInfoResponse.LicenseInfo("uid", "PLATINUM", "PLATINUM", License.Status.EXPIRED, randomNonNegativeLong());
+    }
+}
diff --git a/x-pack/plugin/src/test/resources/rest-api-spec/test/rollup/put_job.yml b/x-pack/plugin/src/test/resources/rest-api-spec/test/rollup/put_job.yml
index 717be0d6b25..98ef9b32e3d 100644
--- a/x-pack/plugin/src/test/resources/rest-api-spec/test/rollup/put_job.yml
+++ b/x-pack/plugin/src/test/resources/rest-api-spec/test/rollup/put_job.yml
@@ -188,3 +188,33 @@ setup:
             ]
           }
 
+---
+"Unknown Metric":
+
+  - do:
+      catch: /Unsupported metric \[does_not_exist\]/
+      headers:
+        Authorization: "Basic eF9wYWNrX3Jlc3RfdXNlcjp4LXBhY2stdGVzdC1wYXNzd29yZA==" # run as x_pack_rest_user, i.e. the test setup superuser
+      xpack.rollup.put_job:
+        id: foo
+        body:  >
+          {
+            "index_pattern": "foo",
+            "rollup_index": "foo_rollup",
+            "cron": "*/30 * * * * ?",
+            "page_size" :10,
+            "groups" : {
+              "date_histogram": {
+                "field": "the_field",
+                "interval": "1h"
+              }
+            },
+            "metrics": [
+              {
+                "field": "value_field",
+                "metrics": ["min", "max", "sum", "does_not_exist"]
+              }
+            ]
+          }
+
+