This method on settings loaded a class, based on a setting value, using

the default classloader. It had all kinds of leniency in how the
classname was found, and simply cannot work with plugins having isolated
classloaders.

This change removes that method. Some of the uses of it were for custom
extension points, like custom repository or discovery types. A lot were
just there to plugin mock implementations for tests. For the settings
that were legitimate, all now support plugins adding the given setting
via onModule. For those that were specific to tests for mocks, they now
use Classes.loadClass (a helper around Class.forName). This is a
temporary measure until (in a future PR) tests can change the
implementation via package private statics.

I also removed a number of unnecessary intermediate modules, added a
"jvm-example" plugin that can be filled in in the future as a smoke test
for breaking plugins, and gave some documentation to "spawn" modules
interface.

closes #12643
closes #12656

1 files changed, 20 insertions, 1 deletions

diff --git a/core/src/test/java/org/elasticsearch/action/IndicesRequestIT.java b/core/src/test/java/org/elasticsearch/action/IndicesRequestIT.java
index 1b95665609..3d017cf8f6 100644
--- a/core/src/test/java/org/elasticsearch/action/IndicesRequestIT.java
+++ b/core/src/test/java/org/elasticsearch/action/IndicesRequestIT.java
@@ -89,6 +89,7 @@ import org.elasticsearch.common.inject.Inject;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.unit.TimeValue;
 import org.elasticsearch.index.query.QueryBuilders;
+import org.elasticsearch.plugins.AbstractPlugin;
 import org.elasticsearch.script.Script;
 import org.elasticsearch.search.action.SearchServiceTransportAction;
 import org.elasticsearch.test.ESIntegTestCase;
@@ -143,7 +144,7 @@ public class IndicesRequestIT extends ESIntegTestCase {
     protected Settings nodeSettings(int nodeOrdinal) {
         return Settings.settingsBuilder()
                 .put(super.nodeSettings(nodeOrdinal))
-                .put(TransportModule.TRANSPORT_SERVICE_TYPE_KEY, InterceptingTransportService.class.getName())
+                .extendArray("plugin.types", InterceptingTransportService.Plugin.class.getName())
                 .build();
     }
 
@@ -843,6 +844,24 @@ public class IndicesRequestIT extends ESIntegTestCase {
 
     public static class InterceptingTransportService extends TransportService {
 
+        public static class Plugin extends AbstractPlugin {
+            @Override
+            public String name() {
+                return "intercepting-transport-service";
+            }
+            @Override
+            public String description() {
+                return "an intercepting transport service for testing";
+            }
+            public void onModule(TransportModule transportModule) {
+                transportModule.addTransportService("intercepting", InterceptingTransportService.class);
+            }
+            @Override
+            public Settings additionalSettings() {
+                return Settings.builder().put(TransportModule.TRANSPORT_SERVICE_TYPE_KEY, "intercepting").build();
+            }
+        }
+
         private final Set<String> actions = new HashSet<>();
 
         private final Map<String, List<TransportRequest>> requests = new HashMap<>();