Add ?storage arg to mount API

docs/reference/searchable-snapshots/apis/mount-snapshot.asciidoc

@@ -49,6 +49,16 @@ include::{es-repo-dir}/rest-api/common-parms.asciidoc[tag=master-timeout]
 (Optional, Boolean) If `true`, the request blocks until the operation is complete.
 Defaults to `false`.
 
+`storage`::
++
+experimental::[]
++
+(Optional, string) Selects the kind of local storage used to accelerate
+searches of the mounted index. If `full_copy`, each node holding a shard of the
+searchable snapshot index makes a full copy of the shard to its local storage.
+If `shared_cache`, the shard uses the
+<<searchable-snapshots-shared-cache,shared cache>>. Defaults to `full_copy`.
+
 [[searchable-snapshots-api-mount-request-body]]
 ==== {api-request-body-title}
 

docs/reference/searchable-snapshots/index.asciidoc

@@ -120,3 +120,13 @@ A snapshot of a {search-snap} index contains only a small amount of metadata
 which identifies its original index snapshot. It does not contain any data from
 the original index. The restore of a backup will fail to restore any
 {search-snap} indices whose original index snapshot is unavailable.
+
+[discrete]
+[[searchable-snapshots-shared-cache]]
+=== Shared snapshot cache
+
+experimental::[]
+
+By default a {search-snap} copies the whole snapshot into the local cluster as
+described above. Nodes can also be configured to create a shared snapshot cache
+which is used to hold a copy of just the frequently-accessed parts of shards.

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ilm/MountSnapshotStep.java

@@ -90,7 +90,9 @@ void performDuringNoSnapshot(IndexMetadata indexMetadata, ClusterState currentCl
             new String[]{LifecycleSettings.LIFECYCLE_NAME},
             // we'll not wait for the snapshot to complete in this step as the async steps are executed from threads that shouldn't
             // perform expensive operations (ie. clusterStateProcessed)
-            false);
+            false,
+            // restoring into the cold tier, so use a full local copy
+            MountSearchableSnapshotRequest.Storage.FULL_COPY);
         getClient().execute(MountSearchableSnapshotAction.INSTANCE, mountSearchableSnapshotRequest,
             ActionListener.wrap(response -> {
                 if (response.status() != RestStatus.OK && response.status() != RestStatus.ACCEPTED) {

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/searchablesnapshots/MountSearchableSnapshotRequest.java

@@ -14,14 +14,17 @@
 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.settings.Settings;
 import org.elasticsearch.common.xcontent.ConstructingObjectParser;
 import org.elasticsearch.common.xcontent.ObjectParser;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.rest.RestRequest;
+import org.elasticsearch.xpack.searchablesnapshots.SearchableSnapshotsConstants;
 
 import java.io.IOException;
 import java.util.Arrays;
+import java.util.Locale;
 import java.util.Objects;
 import java.util.stream.Collectors;
 
@@ -37,12 +40,13 @@ public class MountSearchableSnapshotRequest extends MasterNodeRequest<MountSearc
         "mount_searchable_snapshot", true,
         (a, request) -> new MountSearchableSnapshotRequest(
             Objects.requireNonNullElse((String)a[1], (String)a[0]),
-            request.param("repository"),
-            request.param("snapshot"),
+            Objects.requireNonNull(request.param("repository")),
+            Objects.requireNonNull(request.param("snapshot")),
             (String)a[0],
             Objects.requireNonNullElse((Settings)a[2], Settings.EMPTY),
             Objects.requireNonNullElse((String[])a[3], Strings.EMPTY_ARRAY),
-            request.paramAsBoolean("wait_for_completion", false)));
+            request.paramAsBoolean("wait_for_completion", false),
+            Storage.valueOf(request.param("storage", Storage.FULL_COPY.toString()).toUpperCase(Locale.ROOT))));
 
     private static final ParseField INDEX_FIELD = new ParseField("index");
     private static final ParseField RENAMED_INDEX_FIELD = new ParseField("renamed_index");
@@ -65,19 +69,28 @@ public class MountSearchableSnapshotRequest extends MasterNodeRequest<MountSearc
     private final Settings indexSettings;
     private final String[] ignoredIndexSettings;
     private final boolean waitForCompletion;
+    private final Storage storage;
 
     /**
      * Constructs a new mount searchable snapshot request, restoring an index with the settings needed to make it a searchable snapshot.
      */
-    public MountSearchableSnapshotRequest(String mountedIndexName, String repositoryName, String snapshotName, String snapshotIndexName,
-                                          Settings indexSettings, String[] ignoredIndexSettings, boolean waitForCompletion) {
+    public MountSearchableSnapshotRequest(
+            String mountedIndexName,
+            String repositoryName,
+            String snapshotName,
+            String snapshotIndexName,
+            Settings indexSettings,
+            String[] ignoredIndexSettings,
+            boolean waitForCompletion,
+            Storage storage) {
         this.mountedIndexName = Objects.requireNonNull(mountedIndexName);
         this.repositoryName = Objects.requireNonNull(repositoryName);
         this.snapshotName = Objects.requireNonNull(snapshotName);
         this.snapshotIndexName = Objects.requireNonNull(snapshotIndexName);
         this.indexSettings = Objects.requireNonNull(indexSettings);
         this.ignoredIndexSettings = Objects.requireNonNull(ignoredIndexSettings);
         this.waitForCompletion = waitForCompletion;
+        this.storage = storage;
     }
 
     public MountSearchableSnapshotRequest(StreamInput in) throws IOException {
@@ -89,6 +102,11 @@ public MountSearchableSnapshotRequest(StreamInput in) throws IOException {
         this.indexSettings = readSettingsFromStream(in);
         this.ignoredIndexSettings = in.readStringArray();
         this.waitForCompletion = in.readBoolean();
+        if (in.getVersion().onOrAfter(SearchableSnapshotsConstants.SHARED_CACHE_VERSION)) {
+            this.storage = Storage.readFromStream(in);
+        } else {
+            this.storage = Storage.FULL_COPY;
+        }
     }
 
     @Override
@@ -101,6 +119,12 @@ public void writeTo(StreamOutput out) throws IOException {
         writeSettingsToStream(indexSettings, out);
         out.writeStringArray(ignoredIndexSettings);
         out.writeBoolean(waitForCompletion);
+        if (out.getVersion().onOrAfter(SearchableSnapshotsConstants.SHARED_CACHE_VERSION)) {
+            storage.writeTo(out);
+        } else if (storage != Storage.FULL_COPY) {
+            throw new UnsupportedOperationException(
+                    "storage type [" + storage + "] is not supported on version [" + out.getVersion() + "]");
+        }
     }
 
     @Override
@@ -162,6 +186,13 @@ public String[] ignoreIndexSettings() {
         return ignoredIndexSettings;
     }
 
+    /**
+     * @return how nodes will use their local storage to accelerate searches of this snapshot
+     */
+    public Storage storage() {
+        return storage;
+    }
+
     @Override
     public String getDescription() {
         return "mount snapshot [" + repositoryName + ":" + snapshotName + ":" + snapshotIndexName + "] as [" + mountedIndexName + "]";
@@ -173,6 +204,7 @@ public boolean equals(Object o) {
         if (o == null || getClass() != o.getClass()) return false;
         MountSearchableSnapshotRequest that = (MountSearchableSnapshotRequest) o;
         return waitForCompletion == that.waitForCompletion &&
+            storage == that.storage &&
             Objects.equals(mountedIndexName, that.mountedIndexName) &&
             Objects.equals(repositoryName, that.repositoryName) &&
             Objects.equals(snapshotName, that.snapshotName) &&
@@ -185,7 +217,7 @@ public boolean equals(Object o) {
     @Override
     public int hashCode() {
         int result = Objects.hash(mountedIndexName, repositoryName, snapshotName, snapshotIndexName, indexSettings, waitForCompletion,
-            masterNodeTimeout);
+            masterNodeTimeout, storage);
         result = 31 * result + Arrays.hashCode(ignoredIndexSettings);
         return result;
     }
@@ -194,4 +226,21 @@ public int hashCode() {
     public String toString() {
         return getDescription();
     }
+
+    /**
+     * Enumerates the different ways that nodes can use their local storage to accelerate searches of a snapshot.
+     */
+    public enum Storage implements Writeable {
+        FULL_COPY,
+        SHARED_CACHE;
+
+        public static Storage readFromStream(StreamInput in) throws IOException {
+            return in.readEnum(Storage.class);
+        }
+
+        @Override
+        public void writeTo(StreamOutput out) throws IOException {
+            out.writeEnum(this);
+        }
+    }
 }

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/searchablesnapshots/SearchableSnapshotsConstants.java

@@ -6,6 +6,7 @@
  */
 package org.elasticsearch.xpack.searchablesnapshots;
 
+import org.elasticsearch.Version;
 import org.elasticsearch.common.settings.Settings;
 
 import static org.elasticsearch.index.IndexModule.INDEX_STORE_TYPE_SETTING;
@@ -27,4 +28,6 @@ public static boolean isSearchableSnapshotStore(Settings indexSettings) {
 
     public static final String SNAPSHOT_BLOB_CACHE_INDEX = ".snapshot-blob-cache";
 
+    public static final Version SHARED_CACHE_VERSION = Version.V_8_0_0;
+
 }

x-pack/plugin/searchable-snapshots/src/internalClusterTest/java/org/elasticsearch/xpack/searchablesnapshots/BaseSearchableSnapshotsIntegTestCase.java

@@ -126,7 +126,8 @@ protected void mountSnapshot(
                 .put(restoredIndexSettings)
                 .build(),
             Strings.EMPTY_ARRAY,
-            true
+            true,
+            MountSearchableSnapshotRequest.Storage.FULL_COPY
         );
 
         final RestoreSnapshotResponse restoreResponse = client().execute(MountSearchableSnapshotAction.INSTANCE, mountRequest).get();

x-pack/plugin/searchable-snapshots/src/internalClusterTest/java/org/elasticsearch/xpack/searchablesnapshots/ClusterStateApplierOrderingTests.java

@@ -73,7 +73,8 @@ public void testRepositoriesServiceClusterStateApplierIsCalledBeforeIndicesClust
             indexName,
             indexSettingsBuilder.build(),
             Strings.EMPTY_ARRAY,
-            true
+            true,
+            MountSearchableSnapshotRequest.Storage.FULL_COPY
         );
 
         final RestoreSnapshotResponse restoreSnapshotResponse = client().execute(MountSearchableSnapshotAction.INSTANCE, req).get();

x-pack/plugin/searchable-snapshots/src/internalClusterTest/java/org/elasticsearch/xpack/searchablesnapshots/SearchableSnapshotsCanMatchOnCoordinatorIntegTests.java

@@ -133,7 +133,8 @@ public void testSearchableSnapshotShardsAreSkippedWithoutQueryingAnyNodeWhenThey
             indexOutsideSearchRange,
             restoredIndexSettings,
             Strings.EMPTY_ARRAY,
-            false
+            false,
+            MountSearchableSnapshotRequest.Storage.FULL_COPY
         );
         client().execute(MountSearchableSnapshotAction.INSTANCE, mountRequest).actionGet();
 
@@ -267,7 +268,8 @@ public void testQueryPhaseIsExecutedInAnAvailableNodeWhenAllShardsCanBeSkipped()
             indexOutsideSearchRange,
             restoredIndexSettings,
             Strings.EMPTY_ARRAY,
-            false
+            false,
+            MountSearchableSnapshotRequest.Storage.FULL_COPY
         );
         client().execute(MountSearchableSnapshotAction.INSTANCE, mountRequest).actionGet();
         final int searchableSnapshotShardCount = indexOutsideSearchRangeShardCount;
@@ -375,7 +377,8 @@ public void testSearchableSnapshotShardsThatHaveMatchingDataAreNotSkippedOnTheCo
             indexWithinSearchRange,
             restoredIndexSettings,
             Strings.EMPTY_ARRAY,
-            false
+            false,
+            MountSearchableSnapshotRequest.Storage.FULL_COPY
         );
         client().execute(MountSearchableSnapshotAction.INSTANCE, mountRequest).actionGet();
 

x-pack/plugin/searchable-snapshots/src/internalClusterTest/java/org/elasticsearch/xpack/searchablesnapshots/SearchableSnapshotsIntegTests.java

@@ -216,7 +216,8 @@ public void testCreateAndRestoreSearchableSnapshot() throws Exception {
             indexName,
             indexSettingsBuilder.build(),
             Strings.EMPTY_ARRAY,
-            true
+            true,
+            MountSearchableSnapshotRequest.Storage.FULL_COPY
         );
 
         final RestoreSnapshotResponse restoreSnapshotResponse = client().execute(MountSearchableSnapshotAction.INSTANCE, req).get();
@@ -446,7 +447,7 @@ public void testCreateAndRestorePartialSearchableSnapshot() throws Exception {
             assertAcked(client().admin().indices().prepareClose(indexName));
         }
 
-        logger.info("--> restoring partial index [{}] with cache enabled");
+        logger.info("--> restoring partial index [{}] with cache enabled", restoredIndexName);
 
         Settings.Builder indexSettingsBuilder = Settings.builder()
             .put(SearchableSnapshots.SNAPSHOT_CACHE_ENABLED_SETTING.getKey(), true)
@@ -478,7 +479,6 @@ public void testCreateAndRestorePartialSearchableSnapshot() throws Exception {
         } else {
             expectedDataTiersPreference = DATA_TIERS_PREFERENCE;
         }
-        indexSettingsBuilder.put(SearchableSnapshots.SNAPSHOT_PARTIAL_SETTING.getKey(), true);
 
         final MountSearchableSnapshotRequest req = new MountSearchableSnapshotRequest(
             restoredIndexName,
@@ -487,7 +487,8 @@ public void testCreateAndRestorePartialSearchableSnapshot() throws Exception {
             indexName,
             indexSettingsBuilder.build(),
             Strings.EMPTY_ARRAY,
-            true
+            true,
+            MountSearchableSnapshotRequest.Storage.SHARED_CACHE
         );
 
         final RestoreSnapshotResponse restoreSnapshotResponse = client().execute(MountSearchableSnapshotAction.INSTANCE, req).get();
@@ -728,7 +729,8 @@ public void testCanMountSnapshotTakenWhileConcurrentlyIndexing() throws Exceptio
             indexName,
             indexSettingsBuilder.build(),
             Strings.EMPTY_ARRAY,
-            true
+            true,
+            MountSearchableSnapshotRequest.Storage.FULL_COPY
         );
 
         final RestoreSnapshotResponse restoreSnapshotResponse = client().execute(MountSearchableSnapshotAction.INSTANCE, req).get();
@@ -783,7 +785,8 @@ public void testMaxRestoreBytesPerSecIsUsed() throws Exception {
             indexName,
             Settings.builder().put(IndexSettings.INDEX_CHECK_ON_STARTUP.getKey(), Boolean.FALSE.toString()).build(),
             Strings.EMPTY_ARRAY,
-            true
+            true,
+            MountSearchableSnapshotRequest.Storage.FULL_COPY
         );
 
         final RestoreSnapshotResponse restore = client().execute(MountSearchableSnapshotAction.INSTANCE, mount).get();
@@ -862,7 +865,8 @@ public void testMountedSnapshotHasNoReplicasByDefault() throws Exception {
                 indexName,
                 indexSettingsBuilder.build(),
                 Strings.EMPTY_ARRAY,
-                true
+                true,
+                MountSearchableSnapshotRequest.Storage.FULL_COPY
             );
 
             final RestoreSnapshotResponse restoreSnapshotResponse = client().execute(MountSearchableSnapshotAction.INSTANCE, req).get();
@@ -896,7 +900,8 @@ public void testMountedSnapshotHasNoReplicasByDefault() throws Exception {
                 indexName,
                 indexSettingsBuilder.build(),
                 Strings.EMPTY_ARRAY,
-                true
+                true,
+                MountSearchableSnapshotRequest.Storage.FULL_COPY
             );
 
             final RestoreSnapshotResponse restoreSnapshotResponse = client().execute(MountSearchableSnapshotAction.INSTANCE, req).get();
@@ -929,7 +934,8 @@ public void testMountedSnapshotHasNoReplicasByDefault() throws Exception {
                 indexName,
                 indexSettingsBuilder.build(),
                 Strings.EMPTY_ARRAY,
-                true
+                true,
+                MountSearchableSnapshotRequest.Storage.FULL_COPY
             );
 
             final RestoreSnapshotResponse restoreSnapshotResponse = client().execute(MountSearchableSnapshotAction.INSTANCE, req).get();

x-pack/plugin/searchable-snapshots/src/internalClusterTest/java/org/elasticsearch/xpack/searchablesnapshots/SearchableSnapshotsLicenseIntegTests.java

@@ -77,7 +77,8 @@ public void createAndMountSearchableSnapshot() throws Exception {
             indexName,
             indexSettingsBuilder.build(),
             Strings.EMPTY_ARRAY,
-            true
+            true,
+            randomFrom(MountSearchableSnapshotRequest.Storage.values())
         );
 
         final RestoreSnapshotResponse restoreSnapshotResponse = client().execute(MountSearchableSnapshotAction.INSTANCE, req).get();
@@ -96,7 +97,8 @@ public void testMountRequiresLicense() {
             indexName,
             Settings.EMPTY,
             Strings.EMPTY_ARRAY,
-            randomBoolean()
+            randomBoolean(),
+            randomFrom(MountSearchableSnapshotRequest.Storage.values())
         );
 
         final ActionFuture<RestoreSnapshotResponse> future = client().execute(MountSearchableSnapshotAction.INSTANCE, req);

x-pack/plugin/searchable-snapshots/src/internalClusterTest/java/org/elasticsearch/xpack/searchablesnapshots/SearchableSnapshotsPrewarmingIntegTests.java

@@ -224,7 +224,8 @@ public void testConcurrentPrewarming() throws Exception {
                             indexName,
                             restoredIndexSettings,
                             Strings.EMPTY_ARRAY,
-                            true
+                            true,
+                            MountSearchableSnapshotRequest.Storage.FULL_COPY
                         )
                     ).get();
 

x-pack/plugin/searchable-snapshots/src/internalClusterTest/java/org/elasticsearch/xpack/searchablesnapshots/SearchableSnapshotsSettingValidationIntegTests.java

@@ -44,7 +44,8 @@ public void createAndMountSearchableSnapshot() throws Exception {
             indexName,
             indexSettingsBuilder.build(),
             Strings.EMPTY_ARRAY,
-            true
+            true,
+            randomFrom(MountSearchableSnapshotRequest.Storage.values())
         );
 
         final RestoreSnapshotResponse restoreSnapshotResponse = client().execute(MountSearchableSnapshotAction.INSTANCE, req).get();

x-pack/plugin/searchable-snapshots/src/internalClusterTest/java/org/elasticsearch/xpack/searchablesnapshots/SearchableSnapshotsSystemIndicesIntegTests.java

@@ -72,7 +72,8 @@ private void executeTest(final String indexName, final Client client) throws Exc
             indexName,
             Settings.builder().put(IndexMetadata.SETTING_INDEX_HIDDEN, randomBoolean()).build(),
             Strings.EMPTY_ARRAY,
-            true
+            true,
+            randomFrom(MountSearchableSnapshotRequest.Storage.values())
         );
 
         final ElasticsearchException exception = expectThrows(

x-pack/plugin/searchable-snapshots/src/internalClusterTest/java/org/elasticsearch/xpack/searchablesnapshots/SearchableSnapshotsUuidValidationIntegTests.java

@@ -101,7 +101,8 @@ public void testMountFailsIfSnapshotChanged() throws Exception {
             indexName,
             Settings.EMPTY,
             Strings.EMPTY_ARRAY,
-            true
+            true,
+            randomFrom(MountSearchableSnapshotRequest.Storage.values())
         );
 
         final ActionFuture<RestoreSnapshotResponse> responseFuture = client().execute(MountSearchableSnapshotAction.INSTANCE, req);