[7.x] Deprecation of transient cluster settings (#78794) (#79288)

This PR changes uses of transient cluster settings to
persistent cluster settings.

The PR also deprecates the transient settings usage.

Relates to #49540

client/rest-high-level/src/test/java/org/elasticsearch/client/ClusterClientIT.java

@@ -75,9 +75,10 @@ public class ClusterClientIT extends ESRestHighLevelClientTestCase {
         ClusterUpdateSettingsRequest setRequest = new ClusterUpdateSettingsRequest();
         setRequest.transientSettings(transientSettings);
         setRequest.persistentSettings(map);
+        RequestOptions options = RequestOptions.DEFAULT.toBuilder().setWarningsHandler(WarningsHandler.PERMISSIVE).build();
 
         ClusterUpdateSettingsResponse setResponse = execute(setRequest, highLevelClient().cluster()::putSettings,
-            highLevelClient().cluster()::putSettingsAsync);
+            highLevelClient().cluster()::putSettingsAsync, options);
 
         assertAcked(setResponse);
         assertThat(setResponse.getTransientSettings().get(transientSettingKey), notNullValue());
@@ -99,7 +100,7 @@ public class ClusterClientIT extends ESRestHighLevelClientTestCase {
         resetRequest.persistentSettings("{\"" + persistentSettingKey + "\": null }", XContentType.JSON);
 
         ClusterUpdateSettingsResponse resetResponse = execute(resetRequest, highLevelClient().cluster()::putSettings,
-            highLevelClient().cluster()::putSettingsAsync);
+            highLevelClient().cluster()::putSettingsAsync, options);
 
         assertThat(resetResponse.getTransientSettings().get(transientSettingKey), equalTo(null));
         assertThat(resetResponse.getPersistentSettings().get(persistentSettingKey), equalTo(null));

client/rest-high-level/src/test/java/org/elasticsearch/client/ESRestHighLevelClientTestCase.java

@@ -221,8 +221,9 @@ public abstract class ESRestHighLevelClientTestCase extends ESRestTestCase {
         ClusterUpdateSettingsRequest request = new ClusterUpdateSettingsRequest();
         request.persistentSettings(persistentSettings);
         request.transientSettings(transientSettings);
+        RequestOptions options = RequestOptions.DEFAULT.toBuilder().setWarningsHandler(WarningsHandler.PERMISSIVE).build();
         assertTrue(execute(
-            request, highLevelClient().cluster()::putSettings, highLevelClient().cluster()::putSettingsAsync).isAcknowledged());
+            request, highLevelClient().cluster()::putSettings, highLevelClient().cluster()::putSettingsAsync, options).isAcknowledged());
     }
 
     protected void putConflictPipeline() throws IOException {
@@ -298,8 +299,9 @@ public abstract class ESRestHighLevelClientTestCase extends ESRestTestCase {
 
         ClusterUpdateSettingsRequest updateSettingsRequest = new ClusterUpdateSettingsRequest();
         updateSettingsRequest.persistentSettings(singletonMap("cluster.remote." + remoteClusterName + ".seeds", transportAddress));
+        RequestOptions options = RequestOptions.DEFAULT.toBuilder().setWarningsHandler(WarningsHandler.PERMISSIVE).build();
         ClusterUpdateSettingsResponse updateSettingsResponse =
-                restHighLevelClient.cluster().putSettings(updateSettingsRequest, RequestOptions.DEFAULT);
+                restHighLevelClient.cluster().putSettings(updateSettingsRequest, options);
         assertThat(updateSettingsResponse.isAcknowledged(), is(true));
 
         assertBusy(() -> {

client/rest-high-level/src/test/java/org/elasticsearch/client/documentation/ClusterClientDocumentationIT.java

@@ -21,6 +21,7 @@ import org.elasticsearch.action.support.master.AcknowledgedResponse;
 import org.elasticsearch.client.ESRestHighLevelClientTestCase;
 import org.elasticsearch.client.RequestOptions;
 import org.elasticsearch.client.RestHighLevelClient;
+import org.elasticsearch.client.WarningsHandler;
 import org.elasticsearch.client.cluster.RemoteConnectionInfo;
 import org.elasticsearch.client.cluster.RemoteInfoRequest;
 import org.elasticsearch.client.cluster.RemoteInfoResponse;
@@ -127,8 +128,9 @@ public class ClusterClientDocumentationIT extends ESRestHighLevelClientTestCase
         request.masterNodeTimeout("1m"); // <2>
         // end::put-settings-request-masterTimeout
 
+        RequestOptions options = RequestOptions.DEFAULT.toBuilder().setWarningsHandler(WarningsHandler.PERMISSIVE).build();
         // tag::put-settings-execute
-        ClusterUpdateSettingsResponse response = client.cluster().putSettings(request, RequestOptions.DEFAULT);
+        ClusterUpdateSettingsResponse response = client.cluster().putSettings(request, options);
         // end::put-settings-execute
 
         // tag::put-settings-response
@@ -144,7 +146,7 @@ public class ClusterClientDocumentationIT extends ESRestHighLevelClientTestCase
         request.transientSettings(Settings.builder().putNull(transientSettingKey).build()); // <1>
         // tag::put-settings-request-reset-transient
         request.persistentSettings(Settings.builder().putNull(persistentSettingKey));
-        ClusterUpdateSettingsResponse resetResponse = client.cluster().putSettings(request, RequestOptions.DEFAULT);
+        ClusterUpdateSettingsResponse resetResponse = client.cluster().putSettings(request, options);
 
         assertTrue(resetResponse.isAcknowledged());
     }

docs/reference/cluster/update-settings.asciidoc

@@ -45,6 +45,8 @@ the setting is the same on all nodes. If, on the other hand, you define differen
 settings on different nodes by accident using the configuration file, it is very
 difficult to notice these discrepancies.
 
+NOTE: Transient settings are deprecated and will be removed in a future release.
+Prefer using persistent cluster settings instead.
 
 [[cluster-update-settings-api-query-params]]
 ==== {api-query-parms-title}
@@ -85,7 +87,7 @@ PUT /_cluster/settings?flat_settings=true
   }
 }
 --------------------------------------------------
-
+// TEST[warning:[transient settings removal] Updating cluster settings through transientSettings is deprecated. Use persistent settings instead.]
 
 The response to an update returns the changed setting, as in this response to
 the transient example:
@@ -114,6 +116,7 @@ PUT /_cluster/settings
   }
 }
 --------------------------------------------------
+// TEST[warning:[transient settings removal] Updating cluster settings through transientSettings is deprecated. Use persistent settings instead.]
 
 
 The response does not include settings that have been reset:
@@ -141,3 +144,4 @@ PUT /_cluster/settings
   }
 }
 --------------------------------------------------
+// TEST[warning:[transient settings removal] Updating cluster settings through transientSettings is deprecated. Use persistent settings instead.]

docs/reference/data-streams/change-mappings-and-settings.asciidoc

@@ -521,7 +521,7 @@ lowers the `indices.lifecycle.poll_interval` setting to `1m` (one minute).
 ----
 PUT /_cluster/settings
 {
-  "transient": {
+  "persistent": {
     "indices.lifecycle.poll_interval": "1m"
   }
 }
@@ -657,7 +657,7 @@ The following update cluster settings API request resets the
 ----
 PUT /_cluster/settings
 {
-  "transient": {
+  "persistent": {
     "indices.lifecycle.poll_interval": null
   }
 }

docs/reference/how-to/fix-common-cluster-issues.asciidoc

@@ -49,7 +49,7 @@ watermarks and remove the write block.
 ----
 PUT _cluster/settings
 {
-  "transient": {
+  "persistent": {
     "cluster.routing.allocation.disk.watermark.low": "90%",
     "cluster.routing.allocation.disk.watermark.high": "95%",
     "cluster.routing.allocation.disk.watermark.flood_stage": "97%"
@@ -80,7 +80,7 @@ When a long-term solution is in place, reset or reconfigure the disk watermarks.
 ----
 PUT _cluster/settings
 {
-  "transient": {
+  "persistent": {
     "cluster.routing.allocation.disk.watermark.low": null,
     "cluster.routing.allocation.disk.watermark.high": null,
     "cluster.routing.allocation.disk.watermark.flood_stage": null

docs/reference/how-to/size-your-shards.asciidoc

@@ -329,7 +329,7 @@ cluster settings API>> and retry the action.
 ----
 PUT _cluster/settings
 {
-  "transient" : {
+  "persistent" : {
     "cluster.max_shards_per_node": 1200
   }
 }
@@ -353,7 +353,7 @@ When a long-term solution is in place, we recommend you reset the
 ----
 PUT _cluster/settings
 {
-  "transient" : {
+  "persistent" : {
     "cluster.max_shards_per_node": null
   }
 }

docs/reference/ilm/ilm-with-existing-indices.asciidoc

@@ -75,7 +75,7 @@ By default, {ilm-init} checks to see what actions need to be taken every 10 minu
 -----------------------
 PUT _cluster/settings
 {
-  "transient": {
+  "persistent": {
     "indices.lifecycle.poll_interval": "1m" <1>
   }
 }
@@ -186,7 +186,7 @@ prevent unnecessary load on the master node:
 -----------------------
 PUT _cluster/settings
 {
-  "transient": {
+  "persistent": {
     "indices.lifecycle.poll_interval": null
   }
 }

docs/reference/ingest/processors/grok.asciidoc

@@ -331,7 +331,7 @@ server log.
 --------------------------------------------------
 PUT _cluster/settings
 {
-  "transient": {
+  "persistent": {
     "logger.org.elasticsearch.ingest.common.GrokProcessor": "debug"
   }
 }

docs/reference/migration/migrate_7_0/search.asciidoc

@@ -74,6 +74,7 @@ PUT /_cluster/settings
   }
 }
 --------------------------------------------------
+// TEST[warning:[transient settings removal] Updating cluster settings through transientSettings is deprecated. Use persistent settings instead.]
 
 
 [discrete]

docs/reference/migration/migrate_7_13.asciidoc

@@ -188,6 +188,7 @@ PUT _cluster/settings
   }
 }
 --------------------------------------------------
+// TEST[warning:[transient settings removal] Updating cluster settings through transientSettings is deprecated. Use persistent settings instead.]
 +
 You can use the {ref}/cat-allocation.html[cat allocation API] to track progress
 of this data migration. If some shards do not migrate then the
@@ -212,6 +213,7 @@ PUT _cluster/settings
   }
 }
 --------------------------------------------------
+// TEST[warning:[transient settings removal] Updating cluster settings through transientSettings is deprecated. Use persistent settings instead.]
 
 6. Discard the data held by the stopped node by deleting the contents of its
 data paths.

docs/reference/modules/cluster/allocation_filtering.asciidoc

@@ -22,7 +22,7 @@ it down, you could create a filter that excludes the node by its IP address:
 --------------------------------------------------
 PUT _cluster/settings
 {
-  "transient" : {
+  "persistent" : {
     "cluster.routing.allocation.exclude._ip" : "10.0.0.1"
   }
 }
@@ -70,7 +70,7 @@ You can use wildcards when specifying attribute values, for example:
 ------------------------
 PUT _cluster/settings
 {
-  "transient": {
+  "persistent": {
     "cluster.routing.allocation.exclude._ip": "192.168.2.*"
   }
 }

docs/reference/modules/cluster/disk_allocator.asciidoc

@@ -157,7 +157,7 @@ gigabytes free, and updating the information about the cluster every minute:
 --------------------------------------------------
 PUT _cluster/settings
 {
-  "transient": {
+  "persistent": {
     "cluster.routing.allocation.disk.watermark.low": "100gb",
     "cluster.routing.allocation.disk.watermark.high": "50gb",
     "cluster.routing.allocation.disk.watermark.flood_stage": "10gb",

docs/reference/modules/cluster/misc.asciidoc

@@ -159,7 +159,7 @@ The settings which control logging can be updated <<dynamic-cluster-setting,dyna
 -------------------------------
 PUT /_cluster/settings
 {
-  "transient": {
+  "persistent": {
     "logger.org.elasticsearch.indices.recovery": "DEBUG"
   }
 }

docs/reference/modules/network/tracers.asciidoc

@@ -16,7 +16,7 @@ the `org.elasticsearch.http.HttpTracer` logger to `TRACE`:
 --------------------------------------------------
 PUT _cluster/settings
 {
-   "transient" : {
+   "persistent" : {
       "logger.org.elasticsearch.http.HttpTracer" : "TRACE"
    }
 }
@@ -29,7 +29,7 @@ exclude wildcard patterns. By default every request will be traced.
 --------------------------------------------------
 PUT _cluster/settings
 {
-   "transient" : {
+   "persistent" : {
       "http.tracer.include" : "*",
       "http.tracer.exclude" : ""
    }
@@ -47,7 +47,7 @@ requests and responses. Activate the tracer by setting the level of the
 --------------------------------------------------
 PUT _cluster/settings
 {
-   "transient" : {
+   "persistent" : {
       "logger.org.elasticsearch.transport.TransportService.tracer" : "TRACE"
    }
 }
@@ -61,7 +61,7 @@ fault detection pings:
 --------------------------------------------------
 PUT _cluster/settings
 {
-   "transient" : {
+   "persistent" : {
       "transport.tracer.include" : "*",
       "transport.tracer.exclude" : "internal:coordination/fault_detection/*"
    }

docs/reference/setup/configuration.asciidoc

@@ -140,6 +140,9 @@ settings API and use `elasticsearch.yml` only for local configurations. Using
 the cluster update settings API ensures the setting is the same on all nodes. If
 you accidentally configure different settings in `elasticsearch.yml` on
 different nodes, it can be difficult to notice discrepancies.
+
+NOTE: Transient settings are deprecated and will be removed in a future release.
+Prefer using persistent cluster settings instead.
 --
 
 [[static-cluster-setting]]

docs/reference/setup/logging-config.asciidoc

@@ -155,7 +155,7 @@ only intended for expert use.
 ----
 PUT /_cluster/settings
 {
-  "transient": {
+  "persistent": {
     "logger.org.elasticsearch.discovery": "DEBUG"
   }
 }

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

@@ -1,6 +1,13 @@
 ---
 "Test put and reset transient settings":
+  - skip:
+      version: " - 7.15.99"
+      reason:  "transient settings deprecation"
+      features: "warnings"
+
   - do:
+      warnings:
+        - "[transient settings removal] Updating cluster settings through transientSettings is deprecated. Use persistent settings instead."
       cluster.put_settings:
         body:
           transient:
@@ -16,6 +23,8 @@
   - match: {transient: {cluster.routing.allocation.enable: "none"}}
 
   - do:
+      warnings:
+        - "[transient settings removal] Updating cluster settings through transientSettings is deprecated. Use persistent settings instead."
       cluster.put_settings:
         body:
           transient:

server/src/main/java/org/elasticsearch/action/admin/cluster/settings/ClusterUpdateSettingsRequest.java

@@ -64,6 +64,11 @@ public class ClusterUpdateSettingsRequest extends AcknowledgedRequest<ClusterUpd
         return validationException;
     }
 
+    /**
+     * @deprecated Transient settings are in the process of being removed. Use
+     * persistent settings to update your cluster settings instead.
+     */
+    @Deprecated
     public Settings transientSettings() {
         return transientSettings;
     }
@@ -74,7 +79,11 @@ public class ClusterUpdateSettingsRequest extends AcknowledgedRequest<ClusterUpd
 
     /**
      * Sets the transient settings to be updated. They will not survive a full cluster restart
+     *
+     * @deprecated Transient settings are in the process of being removed. Use
+     * persistent settings to update your cluster settings instead.
      */
+    @Deprecated
     public ClusterUpdateSettingsRequest transientSettings(Settings settings) {
         this.transientSettings = settings;
         return this;
@@ -82,7 +91,11 @@ public class ClusterUpdateSettingsRequest extends AcknowledgedRequest<ClusterUpd
 
     /**
      * Sets the transient settings to be updated. They will not survive a full cluster restart
+     *
+     * @deprecated Transient settings are in the process of being removed. Use
+     * persistent settings to update your cluster settings instead.
      */
+    @Deprecated
     public ClusterUpdateSettingsRequest transientSettings(Settings.Builder settings) {
         this.transientSettings = settings.build();
         return this;
@@ -90,7 +103,11 @@ public class ClusterUpdateSettingsRequest extends AcknowledgedRequest<ClusterUpd
 
     /**
      * Sets the source containing the transient settings to be updated. They will not survive a full cluster restart
+     *
+     * @deprecated Transient settings are in the process of being removed. Use
+     * persistent settings to update your cluster settings instead.
      */
+    @Deprecated
     public ClusterUpdateSettingsRequest transientSettings(String source, XContentType xContentType) {
         this.transientSettings = Settings.builder().loadFromSource(source, xContentType).build();
         return this;
@@ -98,7 +115,11 @@ public class ClusterUpdateSettingsRequest extends AcknowledgedRequest<ClusterUpd
 
     /**
      * Sets the transient settings to be updated. They will not survive a full cluster restart
+     *
+     * @deprecated Transient settings are in the process of being removed. Use
+     * persistent settings to update your cluster settings instead.
      */
+    @Deprecated
     public ClusterUpdateSettingsRequest transientSettings(Map<String, ?> source) {
         this.transientSettings = Settings.builder().loadFromMap(source).build();
         return this;

server/src/main/java/org/elasticsearch/rest/action/admin/cluster/RestClusterUpdateSettingsAction.java

@@ -11,6 +11,8 @@ package org.elasticsearch.rest.action.admin.cluster;
 import org.elasticsearch.action.admin.cluster.settings.ClusterUpdateSettingsRequest;
 import org.elasticsearch.client.Requests;
 import org.elasticsearch.client.node.NodeClient;
+import org.elasticsearch.common.logging.DeprecationCategory;
+import org.elasticsearch.common.logging.DeprecationLogger;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.xcontent.XContentParser;
 import org.elasticsearch.rest.BaseRestHandler;
@@ -26,6 +28,9 @@ import static java.util.Collections.singletonList;
 import static org.elasticsearch.rest.RestRequest.Method.PUT;
 
 public class RestClusterUpdateSettingsAction extends BaseRestHandler {
+    private static final DeprecationLogger deprecationLogger = DeprecationLogger.getLogger(RestClusterUpdateSettingsAction.class);
+    static final String TRANSIENT_SETTINGS_DEPRECATION_MESSAGE = "[transient settings removal]" +
+        " Updating cluster settings through transientSettings is deprecated. Use persistent settings instead.";
 
     private static final String PERSISTENT = "persistent";
     private static final String TRANSIENT = "transient";
@@ -52,7 +57,15 @@ public class RestClusterUpdateSettingsAction extends BaseRestHandler {
             source = parser.map();
         }
         if (source.containsKey(TRANSIENT)) {
-            clusterUpdateSettingsRequest.transientSettings((Map<String, ?>) source.get(TRANSIENT));
+            Map<String, ?> transientSettings = (Map<String, ?>) source.get(TRANSIENT);
+
+            // We check for empty transient settings map because ClusterUpdateSettingsRequest initializes
+            // each of the settings to an empty collection. When the RestClient is used, we'll get an empty
+            // transient settings map, even if we never set any transient settings.
+            if (transientSettings.isEmpty() == false) {
+                deprecationLogger.warn(DeprecationCategory.SETTINGS, "transient_settings", TRANSIENT_SETTINGS_DEPRECATION_MESSAGE);
+            }
+            clusterUpdateSettingsRequest.transientSettings(transientSettings);
         }
         if (source.containsKey(PERSISTENT)) {
             clusterUpdateSettingsRequest.persistentSettings((Map<String, ?>) source.get(PERSISTENT));

server/src/test/java/org/elasticsearch/index/shard/ShardPathTests.java

@@ -189,8 +189,8 @@ public class ShardPathTests extends ESTestCase {
 
     public void testShardPathSelection() throws IOException {
         try (NodeEnvironment env = newNodeEnvironment(Settings.builder().build())) {
-            NodeEnvironment.NodePath path = env.nodePaths()[0];
+            NodeEnvironment.NodePath[] paths = env.nodePaths();
-            assertEquals(path, ShardPath.getPathWithMostFreeSpace(env));
+            assertThat(org.elasticsearch.core.List.of(paths), hasItem(ShardPath.getPathWithMostFreeSpace(env)));
             ShardId shardId = new ShardId("foo", "0xDEADBEEF", 0);
 
             Settings indexSettings = Settings.builder()
@@ -199,7 +199,13 @@ public class ShardPathTests extends ESTestCase {
 
             ShardPath shardPath = ShardPath.selectNewPathForShard(env, shardId, idxSettings, 1L, new HashMap<>());
             assertNotNull(shardPath.getDataPath());
-            assertEquals(path.indicesPath.resolve("0xDEADBEEF").resolve("0"), shardPath.getDataPath());
+
+            List<Path> indexPaths = new ArrayList<>();
+            for (NodeEnvironment.NodePath nodePath : paths) {
+                indexPaths.add(nodePath.indicesPath.resolve("0xDEADBEEF").resolve("0"));
+            }
+
+            assertThat(indexPaths, hasItem(shardPath.getDataPath()));
             assertEquals("0xDEADBEEF", shardPath.getShardId().getIndex().getUUID());
             assertEquals("foo", shardPath.getShardId().getIndexName());
             assertFalse(shardPath.isCustomDataPath());

test/framework/src/main/java/org/elasticsearch/test/rest/ESRestTestCase.java

@@ -920,6 +920,17 @@ public abstract class ESRestTestCase extends ESTestCase {
 
         if (mustClear) {
             Request request = new Request("PUT", "/_cluster/settings");
+
+            request.setOptions(RequestOptions.DEFAULT.toBuilder().setWarningsHandler(warnings -> {
+                if (warnings.isEmpty()) {
+                    return false;
+                } else if (warnings.size() > 1) {
+                    return true;
+                } else {
+                    return warnings.get(0).startsWith("[transient settings removal]") == false;
+                }
+            }));
+
             request.setJsonEntity(Strings.toString(clearCommand));
             adminClient().performRequest(request);
         }

x-pack/docs/en/security/troubleshooting.asciidoc

@@ -684,13 +684,13 @@ the `basic` `authProvider` in {kib}. The process is documented in the
 
 If the previous resolutions do not solve your issue, enable additional
 logging for the SAML realm to troubleshoot further. You can enable debug
-logging by configuring the following transient setting:
+logging by configuring the following persistent setting:
 
 [source, console]
 ----
 PUT /_cluster/settings
 {
-  "transient": {
+  "persistent": {
     "logger.org.elasticsearch.xpack.security.authc.saml": "debug"
   }
 }

x-pack/plugin/deprecation/qa/rest/src/javaRestTest/java/org/elasticsearch/xpack/deprecation/DeprecationHttpIT.java

@@ -361,7 +361,7 @@ public class DeprecationHttpIT extends ESRestTestCase {
             List<Map<String, Object>> documents = getIndexedDeprecations();
 
             logger.warn(documents);
-            assertThat(documents, hasSize(2));
+            assertThat(documents, hasSize(3));
 
             assertThat(
                 documents,
@@ -373,6 +373,14 @@ public class DeprecationHttpIT extends ESRestTestCase {
                     allOf(
                         hasEntry("event.code", "deprecated_settings"),
                         hasEntry("message", "[deprecated_settings] usage is deprecated. use [settings] instead")
+                    ),
+                    allOf(
+                        hasEntry("event.code", "transient_settings"),
+                        hasEntry(
+                            "message",
+                            "[transient settings removal] Updating cluster settings through transientSettings"
+                                + " is deprecated. Use persistent settings instead."
+                        )
                     )
                 )
             );

x-pack/plugin/deprecation/src/main/java/org/elasticsearch/xpack/deprecation/ClusterDeprecationChecks.java

@@ -413,4 +413,16 @@ public class ClusterDeprecationChecks {
         }
         return null;
     }
+
+    static DeprecationIssue checkTransientSettingsExistence(ClusterState state) {
+        if (state.metadata().transientSettings().isEmpty() == false) {
+            return new DeprecationIssue(DeprecationIssue.Level.WARNING,
+                "Transient cluster settings are in the process of being removed.",
+                "https://ela.st/es-deprecation-7-transient-cluster-settings",
+                "Use persistent settings to define your cluster settings instead.",
+                false,
+                null);
+        }
+        return null;
+    }
 }

x-pack/plugin/deprecation/src/main/java/org/elasticsearch/xpack/deprecation/DeprecationChecks.java

@@ -53,7 +53,8 @@ public class DeprecationChecks {
             ClusterDeprecationChecks::checkClusterRoutingAllocationIncludeRelocationsSetting,
             ClusterDeprecationChecks::checkGeoShapeTemplates,
             ClusterDeprecationChecks::checkSparseVectorTemplates,
-            ClusterDeprecationChecks::checkILMFreezeActions
+            ClusterDeprecationChecks::checkILMFreezeActions,
+            ClusterDeprecationChecks::checkTransientSettingsExistence
         ));
 
     static final List<NodeDeprecationCheck<Settings, PluginsAndModules, ClusterState, XPackLicenseState, DeprecationIssue>>

x-pack/plugin/deprecation/src/test/java/org/elasticsearch/xpack/deprecation/ClusterDeprecationChecksTests.java

@@ -48,6 +48,7 @@ import static org.elasticsearch.xpack.core.ilm.LifecycleSettings.LIFECYCLE_POLL_
 import static org.elasticsearch.xpack.deprecation.DeprecationChecks.CLUSTER_SETTINGS_CHECKS;
 import static org.elasticsearch.xpack.deprecation.IndexDeprecationChecksTests.addRandomFields;
 import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.hasItem;
 import static org.hamcrest.Matchers.hasSize;
 
 public class ClusterDeprecationChecksTests extends ESTestCase {
@@ -355,9 +356,17 @@ public class ClusterDeprecationChecksTests extends ESTestCase {
             null
         );
 
+        final DeprecationIssue otherExpectedIssue = new DeprecationIssue(DeprecationIssue.Level.WARNING,
+            "Transient cluster settings are in the process of being removed.",
+            "https://ela.st/es-deprecation-7-transient-cluster-settings",
+            "Use persistent settings to define your cluster settings instead.",
+            false, null);
+
         List<DeprecationIssue> issues = DeprecationChecks.filterChecks(CLUSTER_SETTINGS_CHECKS, c -> c.apply(clusterState));
-        assertThat(issues, hasSize(1));
+
-        assertThat(issues.get(0), equalTo(expectedIssue));
+        assertThat(issues, hasSize(2));
+        assertThat(issues, hasItem(expectedIssue));
+        assertThat(issues, hasItem(otherExpectedIssue));
 
         final String expectedWarning = String.format(Locale.ROOT,
             "[%s] setting was deprecated in Elasticsearch and will be removed in a future release! " +
@@ -553,4 +562,34 @@ public class ClusterDeprecationChecksTests extends ESTestCase {
                 "remove freeze action from the following ilm policies: [policy1,policy2]", false, null)
         ));
     }
+
+    public void testCheckTransientSettingsExistence() {
+        Settings transientSettings = Settings.builder()
+            .put("indices.recovery.max_bytes_per_sec", "20mb")
+            .build();
+        Metadata metadataWithTransientSettings = Metadata.builder()
+            .transientSettings(transientSettings)
+            .build();
+
+        ClusterState badState = ClusterState.builder(new ClusterName("test")).metadata(metadataWithTransientSettings).build();
+        DeprecationIssue issue = ClusterDeprecationChecks.checkTransientSettingsExistence(badState);
+        assertThat(issue, equalTo(
+            new DeprecationIssue(DeprecationIssue.Level.WARNING,
+                "Transient cluster settings are in the process of being removed.",
+                "https://ela.st/es-deprecation-7-transient-cluster-settings",
+                "Use persistent settings to define your cluster settings instead.",
+                false, null)
+        ));
+
+        Settings persistentSettings = Settings.builder()
+            .put("indices.recovery.max_bytes_per_sec", "20mb")
+            .build();
+        Metadata metadataWithoutTransientSettings = Metadata.builder()
+            .persistentSettings(persistentSettings)
+            .build();
+
+        ClusterState okState = ClusterState.builder(new ClusterName("test")).metadata(metadataWithoutTransientSettings).build();
+        issue = ClusterDeprecationChecks.checkTransientSettingsExistence(okState);
+        assertNull(issue);
+    }
 }