ccs_minimize_roundtrips should default to true for async search for CPS (elastic#135614)

MRT defaults to `true` for `_search` and `false` for `_async_search`.
However, we'd want both to default to `true` for CPS.
An error is returned should the user try to set the value manually.

Fulfils CPS requirement S2D18.

Author: pawankartik-elastic

modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/RestSearchTemplateAction.java

@@ -23,6 +23,7 @@
 
 import java.io.IOException;
 import java.util.List;
+import java.util.Optional;
 import java.util.Set;
 import java.util.function.Predicate;
 
@@ -38,10 +39,12 @@ public class RestSearchTemplateAction extends BaseRestHandler {
 
     private final Predicate<NodeFeature> clusterSupportsFeature;
     private final Settings settings;
+    private final boolean inCpsContext;
 
     public RestSearchTemplateAction(Predicate<NodeFeature> clusterSupportsFeature, Settings settings) {
         this.clusterSupportsFeature = clusterSupportsFeature;
         this.settings = settings;
+        this.inCpsContext = settings != null && settings.getAsBoolean("serverless.cross_project.enabled", false);
     }
 
     @Override
@@ -61,7 +64,7 @@ public String getName() {
 
     @Override
     public RestChannelConsumer prepareRequest(RestRequest request, NodeClient client) throws IOException {
-        if (settings != null && settings.getAsBoolean("serverless.cross_project.enabled", false)) {
+        if (inCpsContext) {
             // accept but drop project_routing param until fully supported
             request.param("project_routing");
         }
@@ -73,7 +76,9 @@ public RestChannelConsumer prepareRequest(RestRequest request, NodeClient client
             request,
             null,
             clusterSupportsFeature,
-            size -> searchRequest.source().size(size)
+            size -> searchRequest.source().size(size),
+            // This endpoint is CPS-enabled so propagate the right value.
+            Optional.of(inCpsContext)
         );
 
         // Creates the search template request

modules/reindex/src/main/java/org/elasticsearch/reindex/AbstractBulkByQueryRestHandler.java

@@ -26,6 +26,7 @@
 
 import java.io.IOException;
 import java.util.Map;
+import java.util.Optional;
 import java.util.function.Consumer;
 import java.util.function.Predicate;
 
@@ -52,7 +53,14 @@ protected void parseInternalRequest(
         SearchRequest searchRequest = internal.getSearchRequest();
 
         try (XContentParser parser = extractRequestSpecificFields(restRequest, bodyConsumers)) {
-            RestSearchAction.parseSearchRequest(searchRequest, restRequest, parser, clusterSupportsFeature, size -> failOnSizeSpecified());
+            RestSearchAction.parseSearchRequest(
+                searchRequest,
+                restRequest,
+                parser,
+                clusterSupportsFeature,
+                size -> failOnSizeSpecified(),
+                Optional.empty()
+            );
         }
 
         searchRequest.source().size(restRequest.paramAsInt("scroll_size", searchRequest.source().size()));

server/src/main/java/org/elasticsearch/rest/action/search/RestSearchAction.java

@@ -43,6 +43,7 @@
 import java.util.Arrays;
 import java.util.List;
 import java.util.Locale;
+import java.util.Optional;
 import java.util.Set;
 import java.util.function.IntConsumer;
 import java.util.function.Predicate;
@@ -68,6 +69,7 @@ public class RestSearchAction extends BaseRestHandler {
     private final SearchUsageHolder searchUsageHolder;
     private final Predicate<NodeFeature> clusterSupportsFeature;
     private final Settings settings;
+    private final boolean inCpsContext;
 
     public RestSearchAction(SearchUsageHolder searchUsageHolder, Predicate<NodeFeature> clusterSupportsFeature) {
         this(searchUsageHolder, clusterSupportsFeature, null);
@@ -77,6 +79,7 @@ public RestSearchAction(SearchUsageHolder searchUsageHolder, Predicate<NodeFeatu
         this.searchUsageHolder = searchUsageHolder;
         this.clusterSupportsFeature = clusterSupportsFeature;
         this.settings = settings;
+        this.inCpsContext = settings != null && settings.getAsBoolean("serverless.cross_project.enabled", false);
     }
 
     @Override
@@ -109,7 +112,7 @@ public RestChannelConsumer prepareRequest(final RestRequest request, final NodeC
         // this might be set by old clients
         request.param("min_compatible_shard_node");
 
-        if (settings != null && settings.getAsBoolean("serverless.cross_project.enabled", false)) {
+        if (inCpsContext) {
             // accept but drop project_routing param until fully supported
             request.param("project_routing");
         }
@@ -128,7 +131,16 @@ public RestChannelConsumer prepareRequest(final RestRequest request, final NodeC
          */
         IntConsumer setSize = size -> searchRequest.source().size(size);
         request.withContentOrSourceParamParserOrNull(
-            parser -> parseSearchRequest(searchRequest, request, parser, clusterSupportsFeature, setSize, searchUsageHolder)
+            parser -> parseSearchRequest(
+                searchRequest,
+                request,
+                parser,
+                clusterSupportsFeature,
+                setSize,
+                searchUsageHolder,
+                // This endpoint is CPS-enabled so propagate the right value.
+                Optional.of(inCpsContext)
+            )
         );
 
         return channel -> {
@@ -146,15 +158,23 @@ public RestChannelConsumer prepareRequest(final RestRequest request, final NodeC
      *        parameter
      * @param clusterSupportsFeature used to check if certain features are available in this cluster
      * @param setSize how the size url parameter is handled. {@code udpate_by_query} and regular search differ here.
+     * @param inCpsContext specifies if we're in CPS context.
+     *                     <br>
+     *                     true - the endpoint that's invoking this method is CPS-enabled and in a CPS/Serverless context.
+     *                     <br>
+     *                     false - the endpoint that's invoking this method is CPS-enabled but not in a CPS/Serverless context.
+     *                     <br>
+     *                     Optional.empty - the endpoint is not CPS-enabled irrespective of the environment.
      */
     public static void parseSearchRequest(
         SearchRequest searchRequest,
         RestRequest request,
         XContentParser requestContentParser,
         Predicate<NodeFeature> clusterSupportsFeature,
-        IntConsumer setSize
+        IntConsumer setSize,
+        Optional<Boolean> inCpsContext
     ) throws IOException {
-        parseSearchRequest(searchRequest, request, requestContentParser, clusterSupportsFeature, setSize, null);
+        parseSearchRequest(searchRequest, request, requestContentParser, clusterSupportsFeature, setSize, null, inCpsContext);
     }
 
     /**
@@ -167,14 +187,22 @@ public static void parseSearchRequest(
      * @param clusterSupportsFeature used to check if certain features are available in this cluster
      * @param setSize how the size url parameter is handled. {@code udpate_by_query} and regular search differ here.
      * @param searchUsageHolder the holder of search usage stats
+     * @param inCpsContext specifies if we're in CPS context.
+     *                     <br>
+     *                     true - the endpoint that's invoking this method is CPS-enabled and in a CPS/Serverless context.
+     *                     <br>
+     *                     false - the endpoint that's invoking this method is CPS-enabled but not in a CPS/Serverless context.
+     *                     <br>
+     *                     Optional.empty - the endpoint is not CPS-enabled irrespective of the environment.
      */
     public static void parseSearchRequest(
         SearchRequest searchRequest,
         RestRequest request,
         @Nullable XContentParser requestContentParser,
         Predicate<NodeFeature> clusterSupportsFeature,
         IntConsumer setSize,
-        @Nullable SearchUsageHolder searchUsageHolder
+        @Nullable SearchUsageHolder searchUsageHolder,
+        Optional<Boolean> inCpsContext
     ) throws IOException {
         if (searchRequest.source() == null) {
             searchRequest.source(new SearchSourceBuilder());
@@ -229,9 +257,17 @@ public static void parseSearchRequest(
         if (searchRequest.pointInTimeBuilder() != null) {
             preparePointInTime(searchRequest, request);
         } else {
-            searchRequest.setCcsMinimizeRoundtrips(
-                request.paramAsBoolean("ccs_minimize_roundtrips", searchRequest.isCcsMinimizeRoundtrips())
-            );
+            if (inCpsContext.orElse(false)) {
+                // We're in CPS environment. MRT should not be settable by the user.
+                if (request.hasParam("ccs_minimize_roundtrips")) {
+                    throw new IllegalArgumentException("Setting ccs_minimize_roundtrips is not supported in cross-project search context");
+                }
+            } else {
+                // Either we're in non-CPS environment or the endpoint isn't CPS enabled, so parse what's in the request.
+                searchRequest.setCcsMinimizeRoundtrips(
+                    request.paramAsBoolean("ccs_minimize_roundtrips", searchRequest.isCcsMinimizeRoundtrips())
+                );
+            }
         }
         if (request.paramAsBoolean("force_synthetic_source", false)) {
             searchRequest.setForceSyntheticSource(true);

x-pack/plugin/async-search/src/main/java/org/elasticsearch/xpack/search/RestSubmitAsyncSearchAction.java

@@ -24,6 +24,7 @@
 import java.io.IOException;
 import java.util.Collections;
 import java.util.List;
+import java.util.Optional;
 import java.util.Set;
 import java.util.function.IntConsumer;
 import java.util.function.Predicate;
@@ -39,6 +40,7 @@ public final class RestSubmitAsyncSearchAction extends BaseRestHandler {
     private final SearchUsageHolder searchUsageHolder;
     private final Predicate<NodeFeature> clusterSupportsFeature;
     private final Settings settings;
+    private final boolean inCpsContext;
 
     public RestSubmitAsyncSearchAction(SearchUsageHolder searchUsageHolder, Predicate<NodeFeature> clusterSupportsFeature) {
         this(searchUsageHolder, clusterSupportsFeature, null);
@@ -52,6 +54,7 @@ public RestSubmitAsyncSearchAction(
         this.searchUsageHolder = searchUsageHolder;
         this.clusterSupportsFeature = clusterSupportsFeature;
         this.settings = settings;
+        this.inCpsContext = settings != null && settings.getAsBoolean("serverless.cross_project.enabled", false);
     }
 
     @Override
@@ -71,9 +74,10 @@ protected RestChannelConsumer prepareRequest(RestRequest request, NodeClient cli
         }
         SubmitAsyncSearchRequest submit = new SubmitAsyncSearchRequest();
 
-        if (settings != null && settings.getAsBoolean("serverless.cross_project.enabled", false)) {
+        if (inCpsContext) {
             // accept but drop project_routing param until fully supported
             request.param("project_routing");
+            submit.getSearchRequest().setCcsMinimizeRoundtrips(true);
         }
 
         IntConsumer setSize = size -> submit.getSearchRequest().source().size(size);
@@ -82,7 +86,16 @@ protected RestChannelConsumer prepareRequest(RestRequest request, NodeClient cli
         // them as supported. We rely on SubmitAsyncSearchRequest#validate to fail in case they are set.
         // Note that ccs_minimize_roundtrips is also set this way, which is a supported option.
         request.withContentOrSourceParamParserOrNull(
-            parser -> parseSearchRequest(submit.getSearchRequest(), request, parser, clusterSupportsFeature, setSize, searchUsageHolder)
+            parser -> parseSearchRequest(
+                submit.getSearchRequest(),
+                request,
+                parser,
+                clusterSupportsFeature,
+                setSize,
+                searchUsageHolder,
+                // This endpoint is CPS-enabled so propagate the right value.
+                Optional.of(inCpsContext)
+            )
         );
 
         if (request.hasParam("wait_for_completion_timeout")) {

x-pack/plugin/fleet/src/main/java/org/elasticsearch/xpack/fleet/rest/RestFleetSearchAction.java

@@ -26,6 +26,7 @@
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
+import java.util.Optional;
 import java.util.Set;
 import java.util.function.IntConsumer;
 import java.util.function.Predicate;
@@ -70,7 +71,16 @@ protected RestChannelConsumer prepareRequest(RestRequest request, NodeClient cli
 
         IntConsumer setSize = size -> searchRequest.source().size(size);
         request.withContentOrSourceParamParserOrNull(parser -> {
-            RestSearchAction.parseSearchRequest(searchRequest, request, parser, clusterSupportsFeature, setSize, searchUsageHolder);
+            RestSearchAction.parseSearchRequest(
+                searchRequest,
+                request,
+                parser,
+                clusterSupportsFeature,
+                setSize,
+                searchUsageHolder,
+                // This endpoint is not CPS-enabled.
+                Optional.empty()
+            );
             String[] stringWaitForCheckpoints = request.paramAsStringArray("wait_for_checkpoints", Strings.EMPTY_ARRAY);
             final long[] waitForCheckpoints = new long[stringWaitForCheckpoints.length];
             for (int i = 0; i < stringWaitForCheckpoints.length; ++i) {

x-pack/plugin/rollup/src/main/java/org/elasticsearch/xpack/rollup/rest/RestRollupSearchAction.java

@@ -17,6 +17,7 @@
 
 import java.io.IOException;
 import java.util.List;
+import java.util.Optional;
 import java.util.Set;
 import java.util.function.Predicate;
 
@@ -52,7 +53,9 @@ protected RestChannelConsumer prepareRequest(RestRequest restRequest, NodeClient
                 restRequest,
                 parser,
                 clusterSupportsFeature,
-                size -> searchRequest.source().size(size)
+                size -> searchRequest.source().size(size),
+                // This endpoint is not CPS-enabled.
+                Optional.empty()
             )
         );
         RestSearchAction.validateSearchRequest(restRequest, searchRequest);