Remove `discovery.type` BWC layer from the EC2/Azure/GCE plugins #25080

Those plugins don't replace the discovery logic but rather only provide a custom unicast host provider for their respective platforms. in 5.1 we introduced the  `discovery.zen.hosts_provider` setting to better reflect it. This PR removes BWC code in those plugins as it is not needed anymore

Fixes #24543

plugins/discovery-azure-classic/src/main/java/org/elasticsearch/plugin/discovery/azure/classic/AzureDiscoveryPlugin.java

@@ -22,24 +22,15 @@ package org.elasticsearch.plugin.discovery.azure.classic;
 import org.apache.logging.log4j.Logger;
 import org.elasticsearch.cloud.azure.classic.management.AzureComputeService;
 import org.elasticsearch.cloud.azure.classic.management.AzureComputeServiceImpl;
-import org.elasticsearch.cluster.routing.allocation.AllocationService;
-import org.elasticsearch.cluster.service.ClusterApplier;
-import org.elasticsearch.cluster.service.MasterService;
-import org.elasticsearch.common.io.stream.NamedWriteableRegistry;
 import org.elasticsearch.common.logging.DeprecationLogger;
 import org.elasticsearch.common.logging.Loggers;
 import org.elasticsearch.common.network.NetworkService;
-import org.elasticsearch.common.settings.ClusterSettings;
 import org.elasticsearch.common.settings.Setting;
 import org.elasticsearch.common.settings.Settings;
-import org.elasticsearch.discovery.Discovery;
-import org.elasticsearch.discovery.DiscoveryModule;
 import org.elasticsearch.discovery.azure.classic.AzureUnicastHostsProvider;
 import org.elasticsearch.discovery.zen.UnicastHostsProvider;
-import org.elasticsearch.discovery.zen.ZenDiscovery;
 import org.elasticsearch.plugins.DiscoveryPlugin;
 import org.elasticsearch.plugins.Plugin;
-import org.elasticsearch.threadpool.ThreadPool;
 import org.elasticsearch.transport.TransportService;
 
 import java.util.Arrays;
@@ -73,17 +64,7 @@ public class AzureDiscoveryPlugin extends Plugin implements DiscoveryPlugin {
             () -> new AzureUnicastHostsProvider(settings, createComputeService(), transportService, networkService));
     }
 
-    @Override
-    public Map<String, Supplier<Discovery>> getDiscoveryTypes(ThreadPool threadPool, TransportService transportService,
-                                                              NamedWriteableRegistry namedWriteableRegistry,
-                                                              MasterService masterService, ClusterApplier clusterApplier,
-                                                              ClusterSettings clusterSettings, UnicastHostsProvider hostsProvider,
-                                                              AllocationService allocationService) {
-        // this is for backcompat with pre 5.1, where users would set discovery.type to use ec2 hosts provider
-        return Collections.singletonMap(AZURE, () ->
-            new ZenDiscovery(settings, threadPool, transportService, namedWriteableRegistry, masterService, clusterApplier,
-                clusterSettings, hostsProvider, allocationService));
-    }
+
 
     @Override
     public List<Setting<?>> getSettings() {
@@ -99,19 +80,5 @@ public class AzureDiscoveryPlugin extends Plugin implements DiscoveryPlugin {
                             AzureComputeService.Discovery.ENDPOINT_NAME_SETTING);
     }
 
-    @Override
-    public Settings additionalSettings() {
-        // For 5.0, the hosts provider was "zen", but this was before the discovery.zen.hosts_provider
-        // setting existed. This check looks for the legacy setting, and sets hosts provider if set
-        String discoveryType = DiscoveryModule.DISCOVERY_TYPE_SETTING.get(settings);
-        if (discoveryType.equals(AZURE)) {
-            deprecationLogger.deprecated("using [" + DiscoveryModule.DISCOVERY_TYPE_SETTING.getKey() +
-                "] to set hosts provider is deprecated; " +
-                "set \"" + DiscoveryModule.DISCOVERY_HOSTS_PROVIDER_SETTING.getKey() + ": " + AZURE + "\" instead");
-            if (DiscoveryModule.DISCOVERY_HOSTS_PROVIDER_SETTING.exists(settings) == false) {
-                return Settings.builder().put(DiscoveryModule.DISCOVERY_HOSTS_PROVIDER_SETTING.getKey(), AZURE).build();
-            }
-        }
-        return Settings.EMPTY;
-    }
+
 }

plugins/discovery-azure-classic/src/test/java/org/elasticsearch/cloud/azure/classic/AbstractAzureComputeServiceTestCase.java

@@ -23,8 +23,6 @@ import org.elasticsearch.action.admin.cluster.node.info.NodesInfoResponse;
 import org.elasticsearch.cloud.azure.classic.management.AzureComputeService.Discovery;
 import org.elasticsearch.cloud.azure.classic.management.AzureComputeService.Management;
 import org.elasticsearch.common.settings.Settings;
-import org.elasticsearch.node.Node;
-import org.elasticsearch.plugin.discovery.azure.classic.AzureDiscoveryPlugin;
 import org.elasticsearch.plugins.Plugin;
 import org.elasticsearch.test.ESIntegTestCase;
 
@@ -44,7 +42,7 @@ public abstract class AbstractAzureComputeServiceTestCase extends ESIntegTestCas
     protected Settings nodeSettings(int nodeOrdinal) {
         Settings.Builder builder = Settings.builder()
             .put(super.nodeSettings(nodeOrdinal))
-            .put("discovery.type", "azure");
+            .put("discovery.zen.hosts_provider", "azure");
 
         // We add a fake subscription_id to start mock compute service
         builder.put(Management.SUBSCRIPTION_ID_SETTING.getKey(), "fake")

plugins/discovery-azure-classic/src/test/java/org/elasticsearch/discovery/azure/classic/AzureDiscoveryClusterFormationTests.java

@@ -106,7 +106,7 @@ public class AzureDiscoveryClusterFormationTests extends ESIntegTestCase {
             throw new RuntimeException(e);
         }
         return Settings.builder().put(super.nodeSettings(nodeOrdinal))
-            .put(DiscoveryModule.DISCOVERY_TYPE_SETTING.getKey(), AzureDiscoveryPlugin.AZURE)
+            .put(DiscoveryModule.DISCOVERY_HOSTS_PROVIDER_SETTING.getKey(), AzureDiscoveryPlugin.AZURE)
             .put(Environment.PATH_LOGS_SETTING.getKey(), resolve)
             .put(TransportSettings.PORT.getKey(), 0)
             .put(Node.WRITE_PORTS_FILE_SETTING.getKey(), "true")

plugins/discovery-ec2/src/main/java/org/elasticsearch/discovery/ec2/Ec2DiscoveryPlugin.java

@@ -24,33 +24,24 @@ import org.apache.logging.log4j.Logger;
 import org.apache.lucene.util.IOUtils;
 import org.apache.lucene.util.SetOnce;
 import org.elasticsearch.SpecialPermission;
-import org.elasticsearch.cluster.routing.allocation.AllocationService;
-import org.elasticsearch.cluster.service.ClusterApplier;
 import org.elasticsearch.common.SuppressForbidden;
-import org.elasticsearch.common.io.stream.NamedWriteableRegistry;
 import org.elasticsearch.common.logging.DeprecationLogger;
 import org.elasticsearch.common.logging.Loggers;
 import org.elasticsearch.common.network.NetworkService;
-import org.elasticsearch.common.settings.ClusterSettings;
 import org.elasticsearch.common.settings.Setting;
 import org.elasticsearch.common.settings.Settings;
-import org.elasticsearch.discovery.Discovery;
-import org.elasticsearch.discovery.DiscoveryModule;
-import org.elasticsearch.cluster.service.MasterService;
 import org.elasticsearch.discovery.zen.UnicastHostsProvider;
-import org.elasticsearch.discovery.zen.ZenDiscovery;
 import org.elasticsearch.node.Node;
 import org.elasticsearch.plugins.DiscoveryPlugin;
 import org.elasticsearch.plugins.Plugin;
-import org.elasticsearch.threadpool.ThreadPool;
 import org.elasticsearch.transport.TransportService;
 
+import java.io.UncheckedIOException;
 import java.io.BufferedReader;
-import java.io.Closeable;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
-import java.io.UncheckedIOException;
+import java.io.Closeable;
 import java.net.URL;
 import java.net.URLConnection;
 import java.nio.charset.StandardCharsets;
@@ -95,17 +86,7 @@ public class Ec2DiscoveryPlugin extends Plugin implements DiscoveryPlugin, Close
         this.settings = settings;
     }
 
-    @Override
-    public Map<String, Supplier<Discovery>> getDiscoveryTypes(ThreadPool threadPool, TransportService transportService,
-                                                              NamedWriteableRegistry namedWriteableRegistry,
-                                                              MasterService masterService, ClusterApplier clusterApplier,
-                                                              ClusterSettings clusterSettings, UnicastHostsProvider hostsProvider,
-                                                              AllocationService allocationService) {
-        // this is for backcompat with pre 5.1, where users would set discovery.type to use ec2 hosts provider
-        return Collections.singletonMap(EC2, () ->
-            new ZenDiscovery(settings, threadPool, transportService, namedWriteableRegistry, masterService, clusterApplier,
-                clusterSettings, hostsProvider, allocationService));
-    }
+
 
     @Override
     public NetworkService.CustomNameResolver getCustomNameResolver(Settings settings) {

plugins/discovery-gce/src/main/java/org/elasticsearch/plugin/discovery/gce/GceDiscoveryPlugin.java

@@ -29,24 +29,15 @@ import org.elasticsearch.cloud.gce.GceInstancesServiceImpl;
 import org.elasticsearch.cloud.gce.GceMetadataService;
 import org.elasticsearch.cloud.gce.network.GceNameResolver;
 import org.elasticsearch.cloud.gce.util.Access;
-import org.elasticsearch.cluster.routing.allocation.AllocationService;
-import org.elasticsearch.cluster.service.ClusterApplier;
-import org.elasticsearch.common.io.stream.NamedWriteableRegistry;
 import org.elasticsearch.common.logging.DeprecationLogger;
 import org.elasticsearch.common.logging.Loggers;
 import org.elasticsearch.common.network.NetworkService;
-import org.elasticsearch.common.settings.ClusterSettings;
 import org.elasticsearch.common.settings.Setting;
 import org.elasticsearch.common.settings.Settings;
-import org.elasticsearch.discovery.Discovery;
-import org.elasticsearch.discovery.DiscoveryModule;
-import org.elasticsearch.cluster.service.MasterService;
 import org.elasticsearch.discovery.gce.GceUnicastHostsProvider;
 import org.elasticsearch.discovery.zen.UnicastHostsProvider;
-import org.elasticsearch.discovery.zen.ZenDiscovery;
 import org.elasticsearch.plugins.DiscoveryPlugin;
 import org.elasticsearch.plugins.Plugin;
-import org.elasticsearch.threadpool.ThreadPool;
 import org.elasticsearch.transport.TransportService;
 
 import java.io.Closeable;
@@ -83,17 +74,7 @@ public class GceDiscoveryPlugin extends Plugin implements DiscoveryPlugin, Close
         logger.trace("starting gce discovery plugin...");
     }
 
-    @Override
-    public Map<String, Supplier<Discovery>> getDiscoveryTypes(ThreadPool threadPool, TransportService transportService,
-                                                              NamedWriteableRegistry namedWriteableRegistry,
-                                                              MasterService masterService, ClusterApplier clusterApplier,
-                                                              ClusterSettings clusterSettings, UnicastHostsProvider hostsProvider,
-                                                              AllocationService allocationService) {
-        // this is for backcompat with pre 5.1, where users would set discovery.type to use ec2 hosts provider
-        return Collections.singletonMap(GCE, () ->
-            new ZenDiscovery(settings, threadPool, transportService, namedWriteableRegistry, masterService, clusterApplier,
-                clusterSettings, hostsProvider, allocationService));
-    }
+
 
     @Override
     public Map<String, Supplier<UnicastHostsProvider>> getZenHostsProviders(TransportService transportService,
@@ -122,21 +103,7 @@ public class GceDiscoveryPlugin extends Plugin implements DiscoveryPlugin, Close
             GceInstancesService.MAX_WAIT_SETTING);
     }
 
-    @Override
-    public Settings additionalSettings() {
-        // For 5.0, the hosts provider was "zen", but this was before the discovery.zen.hosts_provider
-        // setting existed. This check looks for the legacy setting, and sets hosts provider if set
-        String discoveryType = DiscoveryModule.DISCOVERY_TYPE_SETTING.get(settings);
-        if (discoveryType.equals(GCE)) {
-            deprecationLogger.deprecated("Using " + DiscoveryModule.DISCOVERY_TYPE_SETTING.getKey() +
-                " setting to set hosts provider is deprecated. " +
-                "Set \"" + DiscoveryModule.DISCOVERY_HOSTS_PROVIDER_SETTING.getKey() + ": " + GCE + "\" instead");
-            if (DiscoveryModule.DISCOVERY_HOSTS_PROVIDER_SETTING.exists(settings) == false) {
-                return Settings.builder().put(DiscoveryModule.DISCOVERY_HOSTS_PROVIDER_SETTING.getKey(), GCE).build();
-            }
-        }
-        return Settings.EMPTY;
-    }
+
 
     @Override
     public void close() throws IOException {

plugins/discovery-gce/src/test/java/org/elasticsearch/discovery/gce/GceDiscoverTests.java

@@ -90,7 +90,7 @@ public class GceDiscoverTests extends ESIntegTestCase {
             throw new RuntimeException(e);
         }
         return Settings.builder().put(super.nodeSettings(nodeOrdinal))
-            .put("discovery.type", "gce")
+            .put("discovery.zen.hosts_provider", "gce")
             .put("path.logs", resolve)
             .put("transport.tcp.port", 0)
             .put("node.portsfile", "true")