Allow query pragmas in release builds (elastic#111953) (elastic#112168)

I have investigated an issue with QA clusters that run release builds. I 
wish I could enable query pragmas to confirm the problem instead of
setting up new clusters and replicating data before testing the theory.
This change allows users to enable query pragmas in release builds.
However, due to the risks associated with using pragmas, the
accept_pragma_risks parameter must be explicitly set to true to proceed.

Author: dnhatn

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/action/EsqlQueryRequest.java

@@ -50,6 +50,7 @@ public class EsqlQueryRequest extends org.elasticsearch.xpack.core.esql.action.E
     private TimeValue keepAlive = DEFAULT_KEEP_ALIVE;
     private boolean keepOnCompletion;
     private boolean onSnapshotBuild = Build.current().isSnapshot();
+    private boolean acceptedPragmaRisks = false;
 
     /**
      * "Tables" provided in the request for use with things like {@code LOOKUP}.
@@ -78,8 +79,9 @@ public ActionRequestValidationException validate() {
         if (Strings.hasText(query) == false) {
             validationException = addValidationError("[" + RequestXContent.QUERY_FIELD + "] is required", validationException);
         }
+
         if (onSnapshotBuild == false) {
-            if (pragmas.isEmpty() == false) {
+            if (pragmas.isEmpty() == false && acceptedPragmaRisks == false) {
                 validationException = addValidationError(
                     "[" + RequestXContent.PRAGMA_FIELD + "] only allowed in snapshot builds",
                     validationException
@@ -230,4 +232,8 @@ public Task createTask(long id, String type, String action, TaskId parentTaskId,
     void onSnapshotBuild(boolean onSnapshotBuild) {
         this.onSnapshotBuild = onSnapshotBuild;
     }
+
+    void acceptedPragmaRisks(boolean accepted) {
+        this.acceptedPragmaRisks = accepted;
+    }
 }

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/action/RequestXContent.java

@@ -69,6 +69,7 @@ String fields() {
     private static final ParseField PARAMS_FIELD = new ParseField("params");
     private static final ParseField LOCALE_FIELD = new ParseField("locale");
     private static final ParseField PROFILE_FIELD = new ParseField("profile");
+    private static final ParseField ACCEPT_PRAGMA_RISKS = new ParseField("accept_pragma_risks");
     static final ParseField TABLES_FIELD = new ParseField("tables");
 
     static final ParseField WAIT_FOR_COMPLETION_TIMEOUT = new ParseField("wait_for_completion_timeout");
@@ -92,6 +93,7 @@ private static void objectParserCommon(ObjectParser<EsqlQueryRequest, ?> parser)
         parser.declareString(EsqlQueryRequest::query, QUERY_FIELD);
         parser.declareBoolean(EsqlQueryRequest::columnar, COLUMNAR_FIELD);
         parser.declareObject(EsqlQueryRequest::filter, (p, c) -> AbstractQueryBuilder.parseTopLevelQuery(p), FILTER_FIELD);
+        parser.declareBoolean(EsqlQueryRequest::acceptedPragmaRisks, ACCEPT_PRAGMA_RISKS);
         parser.declareObject(
             EsqlQueryRequest::pragmas,
             (p, c) -> new QueryPragmas(Settings.builder().loadFromMap(p.map()).build()),

x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/action/EsqlQueryRequestTests.java

@@ -302,6 +302,9 @@ public void testPragmasOnlyValidOnSnapshot() throws IOException {
         request.onSnapshotBuild(false);
         assertNotNull(request.validate());
         assertThat(request.validate().getMessage(), containsString("[pragma] only allowed in snapshot builds"));
+
+        request.acceptedPragmaRisks(true);
+        assertNull(request.validate());
     }
 
     public void testTablesKeyword() throws IOException {