Propogate version in reindex from remote search (#42958)

This is related to #31908. In order to use the external version in a
reindex from remote request, the search request must be configured to
request the version (as it is not returned by default). This commit
modifies the search request to request the version. Additionally, it
modifies our current reindex from remote tests to randomly use the
external version_type.

modules/reindex/build.gradle

@@ -77,7 +77,7 @@ forbiddenPatterns {
     exclude '**/*.p12'
 }
 
-// Support for testing reindex-from-remote against old Elaticsearch versions
+// Support for testing reindex-from-remote against old Elasticsearch versions
 configurations {
   oldesFixture
   es2

modules/reindex/src/main/java/org/elasticsearch/index/reindex/remote/RemoteRequestBuilders.java

@@ -84,14 +84,13 @@ final class RemoteRequestBuilders {
             request.addParameter("scroll", keepAlive.getStringRep());
         }
         request.addParameter("size", Integer.toString(searchRequest.source().size()));
-        if (searchRequest.source().version() == null || searchRequest.source().version() == true) {
-            /*
-             * Passing `null` here just add the `version` request parameter
-             * without any value. This way of requesting the version works
-             * for all supported versions of Elasticsearch.
-             */
-            request.addParameter("version", null);
+
+        if (searchRequest.source().version() == null || searchRequest.source().version() == false) {
+            request.addParameter("version", Boolean.FALSE.toString());
+        } else {
+            request.addParameter("version", Boolean.TRUE.toString());
         }
+
         if (searchRequest.source().sorts() != null) {
             boolean useScan = false;
             // Detect if we should use search_type=scan rather than a sort

modules/reindex/src/test/java/org/elasticsearch/index/reindex/ManyDocumentsIT.java

@@ -73,6 +73,7 @@ public class ManyDocumentsIT extends ESRestTestCase {
         Map<?, ?> http = (Map<?, ?>) nodeInfo.get("http");
         String remote = "http://"+ http.get("publish_address");
         Request request = new Request("POST", "/_reindex");
+        if (randomBoolean()) {
             request.setJsonEntity(
                 "{\n" +
                     "  \"source\":{\n" +
@@ -85,6 +86,22 @@ public class ManyDocumentsIT extends ESRestTestCase {
                     "    \"index\":\"des\"\n" +
                     "  }\n" +
                     "}");
+        } else {
+            // Test with external version_type
+            request.setJsonEntity(
+                "{\n" +
+                    "  \"source\":{\n" +
+                    "    \"index\":\"test\",\n" +
+                    "    \"remote\":{\n" +
+                    "      \"host\":\"" + remote + "\"\n" +
+                    "    }\n" +
+                    "  }\n," +
+                    "  \"dest\":{\n" +
+                    "    \"index\":\"des\",\n" +
+                    "    \"version_type\": \"external\"\n" +
+                    "  }\n" +
+                    "}");
+        }
         Map<String, Object> response = entityAsMap(client().performRequest(request));
         assertThat(response, hasEntry("total", count));
         assertThat(response, hasEntry("created", count));

modules/reindex/src/test/java/org/elasticsearch/index/reindex/remote/ReindexFromOldRemoteIT.java

@@ -56,6 +56,24 @@ public class ReindexFromOldRemoteIT extends ESRestTestCase {
                 }
 
                 Request reindex = new Request("POST", "/_reindex");
+                if (randomBoolean()) {
+                    // Reindex using the external version_type
+                    reindex.setJsonEntity(
+                        "{\n"
+                            + "  \"source\":{\n"
+                            + "    \"index\": \"test\",\n"
+                            + "    \"size\": 1,\n"
+                            + "    \"remote\": {\n"
+                            + "      \"host\": \"http://127.0.0.1:" + oldEsPort + "\"\n"
+                            + "    }\n"
+                            + "  },\n"
+                            + "  \"dest\": {\n"
+                            + "    \"index\": \"test\",\n"
+                            + "    \"version_type\": \"external\"\n"
+                            + "  }\n"
+                            + "}");
+                } else {
+                    // Reindex using the default internal version_type
                     reindex.setJsonEntity(
                         "{\n"
                             + "  \"source\":{\n"
@@ -69,6 +87,7 @@ public class ReindexFromOldRemoteIT extends ESRestTestCase {
                             + "    \"index\": \"test\"\n"
                             + "  }\n"
                             + "}");
+                }
                 reindex.addParameter("refresh", "true");
                 reindex.addParameter("pretty", "true");
                 if (requestsPerSecond != null) {

modules/reindex/src/test/java/org/elasticsearch/index/reindex/remote/RemoteRequestBuildersTests.java

@@ -198,7 +198,12 @@ public class RemoteRequestBuildersTests extends ESTestCase {
             assertScroll(remoteVersion, params, scroll);
         }
         assertThat(params, hasEntry("size", Integer.toString(size)));
-        assertThat(params, fetchVersion == null || fetchVersion == true ? hasEntry("version", null) : not(hasEntry("version", null)));
+        if (fetchVersion != null) {
+            assertThat(params, fetchVersion ? hasEntry("version", Boolean.TRUE.toString()) :
+                hasEntry("version", Boolean.FALSE.toString()));
+        } else {
+            assertThat(params, hasEntry("version", Boolean.FALSE.toString()));
+        }
     }
 
     private void assertScroll(Version remoteVersion, Map<String, String> params, TimeValue requested) {