Implementing pagination for _cat/indices API (opensearch-project#14718)

* Implementing pagination for _cat/indices

Signed-off-by: Harsh Garg <gkharsh@amazon.com>

CHANGELOG.md

@@ -13,6 +13,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Add successfulSearchShardIndices in searchRequestContext ([#15967](https://github.com/opensearch-project/OpenSearch/pull/15967))
 - Remove identity-related feature flagged code from the RestController ([#15430](https://github.com/opensearch-project/OpenSearch/pull/15430))
 - Add support for msearch API to pass search pipeline name - ([#15923](https://github.com/opensearch-project/OpenSearch/pull/15923))
+- Add _list/indices API as paginated alternate to _cat/indices ([#14718](https://github.com/opensearch-project/OpenSearch/pull/14718))
 
 ### Dependencies
 - Bump `com.azure:azure-identity` from 1.13.0 to 1.13.2 ([#15578](https://github.com/opensearch-project/OpenSearch/pull/15578))

server/src/main/java/org/opensearch/action/ActionModule.java

@@ -461,6 +461,9 @@
 import org.opensearch.rest.action.ingest.RestGetPipelineAction;
 import org.opensearch.rest.action.ingest.RestPutPipelineAction;
 import org.opensearch.rest.action.ingest.RestSimulatePipelineAction;
+import org.opensearch.rest.action.list.AbstractListAction;
+import org.opensearch.rest.action.list.RestIndicesListAction;
+import org.opensearch.rest.action.list.RestListAction;
 import org.opensearch.rest.action.search.RestClearScrollAction;
 import org.opensearch.rest.action.search.RestCountAction;
 import org.opensearch.rest.action.search.RestCreatePitAction;
@@ -802,9 +805,14 @@ private ActionFilters setupActionFilters(List<ActionPlugin> actionPlugins) {
 
     public void initRestHandlers(Supplier<DiscoveryNodes> nodesInCluster) {
         List<AbstractCatAction> catActions = new ArrayList<>();
+        List<AbstractListAction> listActions = new ArrayList<>();
         Consumer<RestHandler> registerHandler = handler -> {
             if (handler instanceof AbstractCatAction) {
-                catActions.add((AbstractCatAction) handler);
+                if (handler instanceof AbstractListAction && ((AbstractListAction) handler).isActionPaginated()) {
+                    listActions.add((AbstractListAction) handler);
+                } else {
+                    catActions.add((AbstractCatAction) handler);
+                }
             }
             restController.registerHandler(handler);
         };
@@ -980,6 +988,9 @@ public void initRestHandlers(Supplier<DiscoveryNodes> nodesInCluster) {
         }
         registerHandler.accept(new RestTemplatesAction());
 
+        // LIST API
+        registerHandler.accept(new RestIndicesListAction());
+
         // Point in time API
         registerHandler.accept(new RestCreatePitAction());
         registerHandler.accept(new RestDeletePitAction());
@@ -1011,6 +1022,7 @@ public void initRestHandlers(Supplier<DiscoveryNodes> nodesInCluster) {
             }
         }
         registerHandler.accept(new RestCatAction(catActions));
+        registerHandler.accept(new RestListAction(listActions));
         registerHandler.accept(new RestDecommissionAction());
         registerHandler.accept(new RestGetDecommissionStateAction());
         registerHandler.accept(new RestRemoteStoreStatsAction());

server/src/main/java/org/opensearch/common/Table.java

@@ -34,6 +34,7 @@
 
 import org.opensearch.common.time.DateFormatter;
 import org.opensearch.core.common.Strings;
+import org.opensearch.rest.pagination.PageToken;
 
 import java.time.Instant;
 import java.time.ZoneOffset;
@@ -59,9 +60,19 @@ public class Table {
     private List<Cell> currentCells;
     private boolean inHeaders = false;
     private boolean withTime = false;
+    /**
+     * paginatedQueryResponse if null will imply the Table response is not paginated.
+     */
+    private PageToken pageToken;
     public static final String EPOCH = "epoch";
     public static final String TIMESTAMP = "timestamp";
 
+    public Table() {}
+
+    public Table(@Nullable PageToken pageToken) {
+        this.pageToken = pageToken;
+    }
+
     public Table startHeaders() {
         inHeaders = true;
         currentCells = new ArrayList<>();
@@ -230,6 +241,10 @@ public Map<String, String> getAliasMap() {
         return headerAliasMap;
     }
 
+    public PageToken getPageToken() {
+        return pageToken;
+    }
+
     /**
      * Cell in a table
      *

server/src/main/java/org/opensearch/rest/RestHandler.java

@@ -125,6 +125,13 @@ default boolean allowSystemIndexAccessByDefault() {
         return false;
     }
 
+    /**
+     * Denotes whether the RestHandler will output paginated responses or not.
+     */
+    default boolean isActionPaginated() {
+        return false;
+    }
+
     static RestHandler wrapper(RestHandler delegate) {
         return new Wrapper(delegate);
     }

server/src/main/java/org/opensearch/rest/RestRequest.java

@@ -51,6 +51,7 @@
 import org.opensearch.core.xcontent.XContentParser;
 import org.opensearch.http.HttpChannel;
 import org.opensearch.http.HttpRequest;
+import org.opensearch.rest.pagination.PageParams;
 
 import java.io.IOException;
 import java.io.InputStream;
@@ -67,6 +68,9 @@
 
 import static org.opensearch.common.unit.TimeValue.parseTimeValue;
 import static org.opensearch.core.common.unit.ByteSizeValue.parseBytesSizeValue;
+import static org.opensearch.rest.pagination.PageParams.PARAM_NEXT_TOKEN;
+import static org.opensearch.rest.pagination.PageParams.PARAM_SIZE;
+import static org.opensearch.rest.pagination.PageParams.PARAM_SORT;
 
 /**
  * REST Request
@@ -591,6 +595,10 @@ public static MediaType parseContentType(List<String> header) {
         throw new IllegalArgumentException("empty Content-Type header");
     }
 
+    public PageParams parsePaginatedQueryParams(String defaultSortOrder, int defaultPageSize) {
+        return new PageParams(param(PARAM_NEXT_TOKEN), param(PARAM_SORT, defaultSortOrder), paramAsInt(PARAM_SIZE, defaultPageSize));
+    }
+
     /**
      * Thrown if there is an error in the content type header.
      *