Test: Lookup node versions on rest test start (#34657)

This is a forward port of a change made to clean up backwards
compatibility for the rollup cleanups. It makes the version of each node
available very early on in test execution. The 6.x version of the change
used those versions to control the cleanup backwards compatibility but
that isn't needed in this branch. But having the versions around *is*
useful. So this makes them available.

Closes #34629

test/framework/src/main/java/org/elasticsearch/test/rest/ESRestTestCase.java

@@ -26,6 +26,7 @@ import org.apache.http.message.BasicHeader;
 import org.apache.http.nio.conn.ssl.SSLIOSessionStrategy;
 import org.apache.http.ssl.SSLContexts;
 import org.apache.http.util.EntityUtils;
+import org.elasticsearch.Version;
 import org.elasticsearch.action.admin.cluster.node.tasks.list.ListTasksAction;
 import org.elasticsearch.client.Request;
 import org.elasticsearch.client.Response;
@@ -73,6 +74,7 @@ import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.TreeSet;
 import java.util.concurrent.TimeUnit;
 import java.util.function.Predicate;
 
@@ -105,25 +107,13 @@ public abstract class ESRestTestCase extends ESTestCase {
     }
 
     /**
-     * Does the cluster being tested have xpack installed?
+     * Does any node in the cluster being tested have x-pack installed?
      */
     public static boolean hasXPack() throws IOException {
-        RestClient client = adminClient();
-        if (client == null) {
+        if (hasXPack == null) {
             throw new IllegalStateException("must be called inside of a rest test case test");
         }
-        Map<?, ?> response = entityAsMap(client.performRequest(new Request("GET", "_nodes/plugins")));
-        Map<?, ?> nodes = (Map<?, ?>) response.get("nodes");
-        for (Map.Entry<?, ?> node : nodes.entrySet()) {
-            Map<?, ?> nodeInfo = (Map<?, ?>) node.getValue();
-            for (Object module: (List<?>) nodeInfo.get("modules")) {
-                Map<?, ?> moduleInfo = (Map<?, ?>) module;
-                if (moduleInfo.get("name").toString().startsWith("x-pack-")) {
-                    return true;
-                }
-            }
-        }
-        return false;
+        return hasXPack;
     }
 
     private static List<HttpHost> clusterHosts;
@@ -136,12 +126,16 @@ public abstract class ESRestTestCase extends ESTestCase {
      * completes
      */
     private static RestClient adminClient;
+    private static Boolean hasXPack;
+    private static TreeSet<Version> nodeVersions;
 
     @Before
     public void initClient() throws IOException {
         if (client == null) {
             assert adminClient == null;
             assert clusterHosts == null;
+            assert hasXPack == null;
+            assert nodeVersions == null;
             String cluster = System.getProperty("tests.rest.cluster");
             if (cluster == null) {
                 throw new RuntimeException("Must specify [tests.rest.cluster] system property with a comma delimited list of [host:port] "
@@ -162,10 +156,27 @@ public abstract class ESRestTestCase extends ESTestCase {
             logger.info("initializing REST clients against {}", clusterHosts);
             client = buildClient(restClientSettings(), clusterHosts.toArray(new HttpHost[clusterHosts.size()]));
             adminClient = buildClient(restAdminSettings(), clusterHosts.toArray(new HttpHost[clusterHosts.size()]));
+
+            hasXPack = false;
+            nodeVersions = new TreeSet<>();
+            Map<?, ?> response = entityAsMap(adminClient.performRequest(new Request("GET", "_nodes/plugins")));
+            Map<?, ?> nodes = (Map<?, ?>) response.get("nodes");
+            for (Map.Entry<?, ?> node : nodes.entrySet()) {
+                Map<?, ?> nodeInfo = (Map<?, ?>) node.getValue();
+                nodeVersions.add(Version.fromString(nodeInfo.get("version").toString()));
+                for (Object module: (List<?>) nodeInfo.get("modules")) {
+                    Map<?, ?> moduleInfo = (Map<?, ?>) module;
+                    if (moduleInfo.get("name").toString().startsWith("x-pack-")) {
+                        hasXPack = true;
+                    }
+                }
+            }
         }
         assert client != null;
         assert adminClient != null;
         assert clusterHosts != null;
+        assert hasXPack != null;
+        assert nodeVersions != null;
     }
 
     /**
@@ -195,6 +206,8 @@ public abstract class ESRestTestCase extends ESTestCase {
             clusterHosts = null;
             client = null;
             adminClient = null;
+            hasXPack = null;
+            nodeVersions = null;
         }
     }
 
@@ -335,8 +348,6 @@ public abstract class ESRestTestCase extends ESTestCase {
     }
 
     private void wipeCluster() throws Exception {
-        boolean hasXPack = hasXPack();
-
         if (preserveIndicesUponCompletion() == false) {
             // wipe indices
             try {