Remove transport version from main endpoint response (#97754)

This is a partial backport of #97675.

The transport version is a low level detail of how a node behaves in a
cluster. It was recently added to the main endpoint response, but is too
low level and should be moved to another endpoint TBD. This commit
removes it from the main response, though keeps it as part of the wire
format for the MainResponse to avoid any need for a bwc change to the
format.

docs/reference/setup/install/check-running.asciidoc

@@ -41,8 +41,7 @@ GET /
     "build_snapshot" : false,
     "lucene_version" : "{lucene_version}",
     "minimum_wire_compatibility_version" : "1.2.3",
-    "minimum_index_compatibility_version" : "1.2.3",
-    "transport_version" : "123456"
+    "minimum_index_compatibility_version" : "1.2.3"
   },
   "tagline" : "You Know, for Search"
 }
@@ -55,5 +54,4 @@ GET /
 // TESTRESPONSE[s/"build_snapshot" : false,/"build_snapshot" : $body.version.build_snapshot,/]
 // TESTRESPONSE[s/"minimum_wire_compatibility_version" : "1.2.3"/"minimum_wire_compatibility_version" : $body.version.minimum_wire_compatibility_version/]
 // TESTRESPONSE[s/"minimum_index_compatibility_version" : "1.2.3"/"minimum_index_compatibility_version" : $body.version.minimum_index_compatibility_version/]
-// TESTRESPONSE[s/"transport_version" : "123456"/"transport_version" : $body.version.transport_version/]
 // So much s/// but at least we test that the layout is close to matching....

modules/rest-root/src/main/java/org/elasticsearch/rest/root/MainResponse.java

@@ -28,7 +28,6 @@ public class MainResponse extends ActionResponse implements ToXContentObject {
 
     private String nodeName;
     private Version version;
-    private TransportVersion transportVersion;
     private ClusterName clusterName;
     private String clusterUuid;
     private Build build;
@@ -39,23 +38,18 @@ public class MainResponse extends ActionResponse implements ToXContentObject {
         super(in);
         nodeName = in.readString();
         version = Version.readVersion(in);
-        transportVersion = in.getTransportVersion().onOrAfter(TransportVersion.V_8_500_014) ? TransportVersion.readVersion(in) : null;
+        // ignoring transport version that was temporarily part of the response
+        if (in.getTransportVersion().onOrAfter(TransportVersion.V_8_500_014)) {
+            TransportVersion.readVersion(in);
+        }
         clusterName = new ClusterName(in);
         clusterUuid = in.readString();
         build = Build.readBuild(in);
     }
 
-    public MainResponse(
-        String nodeName,
-        Version version,
-        TransportVersion transportVersion,
-        ClusterName clusterName,
-        String clusterUuid,
-        Build build
-    ) {
+    public MainResponse(String nodeName, Version version, ClusterName clusterName, String clusterUuid, Build build) {
         this.nodeName = nodeName;
         this.version = version;
-        this.transportVersion = transportVersion;
         this.clusterName = clusterName;
         this.clusterUuid = clusterUuid;
         this.build = build;
@@ -69,10 +63,6 @@ public Version getVersion() {
         return version;
     }
 
-    public TransportVersion getTransportVersion() {
-        return transportVersion;
-    }
-
     public ClusterName getClusterName() {
         return clusterName;
     }
@@ -90,7 +80,7 @@ public void writeTo(StreamOutput out) throws IOException {
         out.writeString(nodeName);
         Version.writeVersion(version, out);
         if (out.getTransportVersion().onOrAfter(TransportVersion.V_8_500_019)) {
-            TransportVersion.writeVersion(transportVersion, out);
+            TransportVersion.writeVersion(TransportVersion.current(), out);
         }
         clusterName.writeTo(out);
         out.writeString(clusterUuid);
@@ -113,7 +103,6 @@ public XContentBuilder toXContent(XContentBuilder builder, Params params) throws
             .field("lucene_version", version.luceneVersion().toString())
             .field("minimum_wire_compatibility_version", version.minimumCompatibilityVersion().toString())
             .field("minimum_index_compatibility_version", version.minimumIndexCompatibilityVersion().toString())
-            .field("transport_version", transportVersion.toString())
             .endObject();
         builder.field("tagline", "You Know, for Search");
         builder.endObject();
@@ -147,7 +136,6 @@ public XContentBuilder toXContent(XContentBuilder builder, Params params) throws
             response.version = Version.fromString(
                 ((String) value.get("number")).replace("-SNAPSHOT", "").replaceFirst("-(alpha\\d+|beta\\d+|rc\\d+)", "")
             );
-            response.transportVersion = TransportVersion.fromString(((String) value.get("transport_version")));
         }, (parser, context) -> parser.map(), new ParseField("version"));
     }
 
@@ -166,15 +154,14 @@ public boolean equals(Object o) {
         MainResponse other = (MainResponse) o;
         return Objects.equals(nodeName, other.nodeName)
             && Objects.equals(version, other.version)
-            && Objects.equals(transportVersion, other.transportVersion)
             && Objects.equals(clusterUuid, other.clusterUuid)
             && Objects.equals(build, other.build)
             && Objects.equals(clusterName, other.clusterName);
     }
 
     @Override
     public int hashCode() {
-        return Objects.hash(nodeName, version, transportVersion, clusterUuid, build, clusterName);
+        return Objects.hash(nodeName, version, clusterUuid, build, clusterName);
     }
 
     @Override
@@ -185,8 +172,6 @@ public String toString() {
             + '\''
             + ", version="
             + version
-            + ", transportVersion="
-            + transportVersion
             + ", clusterName="
             + clusterName
             + ", clusterUuid='"

modules/rest-root/src/main/java/org/elasticsearch/rest/root/TransportMainAction.java

@@ -9,7 +9,6 @@
 package org.elasticsearch.rest.root;
 
 import org.elasticsearch.Build;
-import org.elasticsearch.TransportVersion;
 import org.elasticsearch.Version;
 import org.elasticsearch.action.ActionListener;
 import org.elasticsearch.action.support.ActionFilters;
@@ -43,14 +42,7 @@ public TransportMainAction(
     protected void doExecute(Task task, MainRequest request, ActionListener<MainResponse> listener) {
         ClusterState clusterState = clusterService.state();
         listener.onResponse(
-            new MainResponse(
-                nodeName,
-                Version.CURRENT,
-                TransportVersion.current(),
-                clusterState.getClusterName(),
-                clusterState.metadata().clusterUUID(),
-                Build.CURRENT
-            )
+            new MainResponse(nodeName, Version.CURRENT, clusterState.getClusterName(), clusterState.metadata().clusterUUID(), Build.CURRENT)
         );
     }
 }

modules/rest-root/src/test/java/org/elasticsearch/rest/root/MainResponseTests.java

@@ -9,14 +9,12 @@
 package org.elasticsearch.rest.root;
 
 import org.elasticsearch.Build;
-import org.elasticsearch.TransportVersion;
 import org.elasticsearch.Version;
 import org.elasticsearch.cluster.ClusterName;
 import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.xcontent.XContentHelper;
 import org.elasticsearch.test.AbstractXContentSerializingTestCase;
-import org.elasticsearch.test.TransportVersionUtils;
 import org.elasticsearch.test.VersionUtils;
 import org.elasticsearch.xcontent.ToXContent;
 import org.elasticsearch.xcontent.XContentBuilder;
@@ -35,9 +33,8 @@ protected MainResponse createTestInstance() {
         String nodeName = randomAlphaOfLength(10);
         final String date = new Date(randomNonNegativeLong()).toString();
         Version version = VersionUtils.randomIndexCompatibleVersion(random());
-        TransportVersion transportVersion = TransportVersionUtils.randomVersion();
         Build build = new Build(Build.Type.UNKNOWN, randomAlphaOfLength(8), date, randomBoolean(), version.toString());
-        return new MainResponse(nodeName, version, transportVersion, clusterName, clusterUuid, build);
+        return new MainResponse(nodeName, version, clusterName, clusterUuid, build);
     }
 
     @Override
@@ -55,8 +52,7 @@ public void testToXContent() throws IOException {
         final Build current = Build.CURRENT;
         Build build = new Build(current.type(), current.hash(), current.date(), current.isSnapshot(), current.qualifiedVersion());
         Version version = Version.CURRENT;
-        TransportVersion transportVersion = TransportVersion.current();
-        MainResponse response = new MainResponse("nodeName", version, transportVersion, new ClusterName("clusterName"), clusterUUID, build);
+        MainResponse response = new MainResponse("nodeName", version, new ClusterName("clusterName"), clusterUUID, build);
         XContentBuilder builder = XContentFactory.jsonBuilder();
         response.toXContent(builder, ToXContent.EMPTY_PARAMS);
         assertEquals(
@@ -76,8 +72,7 @@ public void testToXContent() throws IOException {
                                 "build_snapshot": %s,
                                 "lucene_version": "%s",
                                 "minimum_wire_compatibility_version": "%s",
-                                "minimum_index_compatibility_version": "%s",
-                                "transport_version": "%s"
+                                "minimum_index_compatibility_version": "%s"
                             },
                             "tagline": "You Know, for Search"
                         }
@@ -90,8 +85,7 @@ public void testToXContent() throws IOException {
                     current.isSnapshot(),
                     version.luceneVersion().toString(),
                     version.minimumCompatibilityVersion().toString(),
-                    version.minimumIndexCompatibilityVersion().toString(),
-                    transportVersion.toString()
+                    version.minimumIndexCompatibilityVersion().toString()
                 )
             ),
             Strings.toString(builder)
@@ -103,19 +97,17 @@ protected MainResponse mutateInstance(MainResponse mutateInstance) {
         String clusterUuid = mutateInstance.getClusterUuid();
         Build build = mutateInstance.getBuild();
         Version version = mutateInstance.getVersion();
-        TransportVersion transportVersion = mutateInstance.getTransportVersion();
         String nodeName = mutateInstance.getNodeName();
         ClusterName clusterName = mutateInstance.getClusterName();
-        switch (randomIntBetween(0, 5)) {
+        switch (randomIntBetween(0, 4)) {
             case 0 -> clusterUuid = clusterUuid + randomAlphaOfLength(5);
             case 1 -> nodeName = nodeName + randomAlphaOfLength(5);
             case 2 ->
                 // toggle the snapshot flag of the original Build parameter
                 build = new Build(Build.Type.UNKNOWN, build.hash(), build.date(), build.isSnapshot() == false, build.qualifiedVersion());
             case 3 -> version = randomValueOtherThan(version, () -> VersionUtils.randomVersion(random()));
             case 4 -> clusterName = new ClusterName(clusterName + randomAlphaOfLength(5));
-            case 5 -> transportVersion = randomValueOtherThan(transportVersion, () -> TransportVersionUtils.randomVersion(random()));
         }
-        return new MainResponse(nodeName, version, transportVersion, clusterName, clusterUuid, build);
+        return new MainResponse(nodeName, version, clusterName, clusterUuid, build);
     }
 }

modules/rest-root/src/test/java/org/elasticsearch/rest/root/RestMainActionTests.java

@@ -9,7 +9,6 @@
 package org.elasticsearch.rest.root;
 
 import org.elasticsearch.Build;
-import org.elasticsearch.TransportVersion;
 import org.elasticsearch.Version;
 import org.elasticsearch.cluster.ClusterName;
 import org.elasticsearch.common.bytes.BytesReference;
@@ -35,10 +34,9 @@ public void testHeadResponse() throws Exception {
         final ClusterName clusterName = new ClusterName("cluster1");
         final String clusterUUID = randomAlphaOfLengthBetween(10, 20);
         final Version version = Version.CURRENT;
-        final TransportVersion transportVersion = TransportVersion.current();
         final Build build = Build.CURRENT;
 
-        final MainResponse mainResponse = new MainResponse(nodeName, version, transportVersion, clusterName, clusterUUID, build);
+        final MainResponse mainResponse = new MainResponse(nodeName, version, clusterName, clusterUUID, build);
         XContentBuilder builder = JsonXContent.contentBuilder();
         RestRequest restRequest = new FakeRestRequest() {
             @Override
@@ -60,11 +58,10 @@ public void testGetResponse() throws Exception {
         final ClusterName clusterName = new ClusterName("cluster1");
         final String clusterUUID = randomAlphaOfLengthBetween(10, 20);
         final Version version = Version.CURRENT;
-        final TransportVersion transportVersion = TransportVersion.current();
         final Build build = Build.CURRENT;
         final boolean prettyPrint = randomBoolean();
 
-        final MainResponse mainResponse = new MainResponse(nodeName, version, transportVersion, clusterName, clusterUUID, build);
+        final MainResponse mainResponse = new MainResponse(nodeName, version, clusterName, clusterUUID, build);
         XContentBuilder builder = JsonXContent.contentBuilder();
 
         Map<String, String> params = new HashMap<>();

x-pack/plugin/sql/jdbc/src/test/java/org/elasticsearch/xpack/sql/jdbc/WebServerTestCase.java

@@ -8,7 +8,6 @@
 package org.elasticsearch.xpack.sql.jdbc;
 
 import org.elasticsearch.Build;
-import org.elasticsearch.TransportVersion;
 import org.elasticsearch.Version;
 import org.elasticsearch.cluster.ClusterName;
 import org.elasticsearch.rest.root.MainResponse;
@@ -50,8 +49,7 @@ MainResponse createMainResponse(Version version) {
         String nodeName = randomAlphaOfLength(10);
         final String date = new Date(randomNonNegativeLong()).toString();
         Build build = new Build(Build.Type.UNKNOWN, randomAlphaOfLength(8), date, randomBoolean(), version.toString());
-        TransportVersion transportVersion = TransportVersion.current();
-        return new MainResponse(nodeName, version, transportVersion, clusterName, clusterUuid, build);
+        return new MainResponse(nodeName, version, clusterName, clusterUuid, build);
     }
 
     String webServerAddress() {