Enable simple remote connection strategy

client/rest-high-level/src/test/java/org/elasticsearch/client/CCRIT.java

@@ -83,7 +83,7 @@ public void setupRemoteClusterConfig() throws Exception {
         String transportAddress = (String) nodesResponse.get("transport_address");
 
         ClusterUpdateSettingsRequest updateSettingsRequest = new ClusterUpdateSettingsRequest();
-        updateSettingsRequest.transientSettings(Collections.singletonMap("cluster.remote.local_cluster.seeds", transportAddress));
+        updateSettingsRequest.transientSettings(Collections.singletonMap("cluster.remote.local_cluster.sniff.seeds", transportAddress));
         ClusterUpdateSettingsResponse updateSettingsResponse =
             highLevelClient().cluster().putSettings(updateSettingsRequest, RequestOptions.DEFAULT);
         assertThat(updateSettingsResponse.isAcknowledged(), is(true));

client/rest-high-level/src/test/java/org/elasticsearch/client/documentation/CCRDocumentationIT.java

@@ -87,7 +87,7 @@ public void setupRemoteClusterConfig() throws IOException {
         String transportAddress = (String) nodesResponse.get("transport_address");
 
         ClusterUpdateSettingsRequest updateSettingsRequest = new ClusterUpdateSettingsRequest();
-        updateSettingsRequest.transientSettings(Collections.singletonMap("cluster.remote.local.seeds", transportAddress));
+        updateSettingsRequest.transientSettings(Collections.singletonMap("cluster.remote.local.sniff.seeds", transportAddress));
         ClusterUpdateSettingsResponse updateSettingsResponse =
             client.cluster().putSettings(updateSettingsRequest, RequestOptions.DEFAULT);
         assertThat(updateSettingsResponse.isAcknowledged(), is(true));

qa/ccs-unavailable-clusters/src/test/java/org/elasticsearch/search/CrossClusterSearchUnavailableClusterIT.java

@@ -144,7 +144,7 @@ public void testSearchSkipUnavailable() throws IOException {
         try (MockTransportService remoteTransport = startTransport("node0", new CopyOnWriteArrayList<>(), Version.CURRENT, threadPool)) {
             DiscoveryNode remoteNode = remoteTransport.getLocalDiscoNode();
 
-            updateRemoteClusterSettings(Collections.singletonMap("seeds", remoteNode.getAddress().toString()));
+            updateRemoteClusterSettings(Collections.singletonMap("sniff.seeds", remoteNode.getAddress().toString()));
 
             for (int i = 0; i < 10; i++) {
                 restHighLevelClient.index(
@@ -229,7 +229,7 @@ public void testSearchSkipUnavailable() throws IOException {
             assertSearchConnectFailure();
 
             Map<String, Object> map = new HashMap<>();
-            map.put("seeds", null);
+            map.put("sniff.seeds", null);
             map.put("skip_unavailable", null);
             updateRemoteClusterSettings(map);
         }
@@ -248,32 +248,32 @@ public void testSkipUnavailableDependsOnSeeds() throws IOException {
                         () -> client().performRequest(request));
                 assertEquals(400, responseException.getResponse().getStatusLine().getStatusCode());
                 assertThat(responseException.getMessage(),
-                        containsString("missing required setting [cluster.remote.remote1.seeds] " +
+                        containsString("missing required setting [cluster.remote.remote1.sniff.seeds] " +
                                 "for setting [cluster.remote.remote1.skip_unavailable]"));
             }
 
             Map<String, Object> settingsMap = new HashMap<>();
-            settingsMap.put("seeds", remoteNode.getAddress().toString());
+            settingsMap.put("sniff.seeds", remoteNode.getAddress().toString());
             settingsMap.put("skip_unavailable", randomBoolean());
             updateRemoteClusterSettings(settingsMap);
 
             {
                 //check that seeds cannot be reset alone if skip_unavailable is set
                 Request request = new Request("PUT", "/_cluster/settings");
-                request.setEntity(buildUpdateSettingsRequestBody(Collections.singletonMap("seeds", null)));
+                request.setEntity(buildUpdateSettingsRequestBody(Collections.singletonMap("sniff.seeds", null)));
                 ResponseException responseException = expectThrows(ResponseException.class,
                         () -> client().performRequest(request));
                 assertEquals(400, responseException.getResponse().getStatusLine().getStatusCode());
-                assertThat(responseException.getMessage(), containsString("missing required setting [cluster.remote.remote1.seeds] " +
+                assertThat(responseException.getMessage(), containsString("missing required setting [cluster.remote.remote1.sniff.seeds] " +
                         "for setting [cluster.remote.remote1.skip_unavailable]"));
             }
 
             if (randomBoolean()) {
                 updateRemoteClusterSettings(Collections.singletonMap("skip_unavailable", null));
-                updateRemoteClusterSettings(Collections.singletonMap("seeds", null));
+                updateRemoteClusterSettings(Collections.singletonMap("sniff.seeds", null));
             } else {
                 Map<String, Object> nullMap = new HashMap<>();
-                nullMap.put("seeds", null);
+                nullMap.put("sniff.seeds", null);
                 nullMap.put("skip_unavailable", null);
                 updateRemoteClusterSettings(nullMap);
             }

qa/full-cluster-restart/src/test/java/org/elasticsearch/upgrades/FullClusterRestartSettingsUpgradeIT.java

@@ -30,12 +30,13 @@
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.common.xcontent.json.JsonXContent;
 import org.elasticsearch.transport.RemoteClusterService;
+import org.elasticsearch.transport.SniffConnectionStrategy;
 
 import java.io.IOException;
 import java.util.Collections;
 
 import static org.elasticsearch.common.xcontent.XContentFactory.jsonBuilder;
-import static org.elasticsearch.transport.RemoteClusterAware.SEARCH_REMOTE_CLUSTERS_SEEDS;
+import static org.elasticsearch.transport.SniffConnectionStrategy.SEARCH_REMOTE_CLUSTERS_SEEDS;
 import static org.elasticsearch.transport.RemoteClusterService.SEARCH_REMOTE_CLUSTER_SKIP_UNAVAILABLE;
 import static org.hamcrest.Matchers.equalTo;
 
@@ -91,9 +92,9 @@ public void testRemoteClusterSettingsUpgraded() throws IOException {
                         RemoteClusterService.REMOTE_CLUSTER_SKIP_UNAVAILABLE.getConcreteSettingForNamespace("foo").exists(settings));
                 assertTrue(RemoteClusterService.REMOTE_CLUSTER_SKIP_UNAVAILABLE.getConcreteSettingForNamespace("foo").get(settings));
                 assertFalse(SEARCH_REMOTE_CLUSTERS_SEEDS.getConcreteSettingForNamespace("foo").exists(settings));
-                assertTrue(RemoteClusterService.REMOTE_CLUSTERS_SEEDS.getConcreteSettingForNamespace("foo").exists(settings));
+                assertTrue(SniffConnectionStrategy.REMOTE_CLUSTER_SEEDS.getConcreteSettingForNamespace("foo").exists(settings));
                 assertThat(
-                        RemoteClusterService.REMOTE_CLUSTERS_SEEDS.getConcreteSettingForNamespace("foo").get(settings),
+                        SniffConnectionStrategy.REMOTE_CLUSTER_SEEDS.getConcreteSettingForNamespace("foo").get(settings),
                         equalTo(Collections.singletonList("localhost:9200")));
             }
         }

qa/multi-cluster-search/src/test/resources/rest-api-spec/test/multi_cluster/100_connection_mode_configuration.yml

@@ -0,0 +1,212 @@
+---
+"Add transient remote cluster in simple mode with invalid sniff settings":
+  - do:
+      cluster.get_settings:
+        include_defaults: true
+
+  - set: { defaults.cluster.remote.my_remote_cluster.seeds.0: remote_ip }
+
+  - do:
+      catch: bad_request
+      cluster.put_settings:
+        flat_settings: true
+        body:
+          transient:
+            cluster.remote.test_remote_cluster.mode: "simple"
+            cluster.remote.test_remote_cluster.sniff.node_connections: "5"
+            cluster.remote.test_remote_cluster.simple.addresses: $remote_ip
+
+  - match: { status: 400 }
+  - match: { error.root_cause.0.type: "illegal_argument_exception" }
+  - match: { error.root_cause.0.reason: "Setting \"cluster.remote.test_remote_cluster.sniff.node_connections\" cannot be
+  used with the configured \"cluster.remote.test_remote_cluster.mode\" [required=SNIFF, configured=SIMPLE]" }
+
+  - do:
+      catch: bad_request
+      cluster.put_settings:
+        flat_settings: true
+        body:
+          transient:
+            cluster.remote.test_remote_cluster.mode: "simple"
+            cluster.remote.test_remote_cluster.sniff.seeds: $remote_ip
+            cluster.remote.test_remote_cluster.simple.addresses: $remote_ip
+
+  - match: { status: 400 }
+  - match: { error.root_cause.0.type: "illegal_argument_exception" }
+  - match: { error.root_cause.0.reason: "Setting \"cluster.remote.test_remote_cluster.sniff.seeds\" cannot be
+   used with the configured \"cluster.remote.test_remote_cluster.mode\" [required=SNIFF, configured=SIMPLE]" }
+
+---
+"Add transient remote cluster in sniff mode with invalid simple settings":
+  - do:
+      cluster.get_settings:
+        include_defaults: true
+
+  - set: { defaults.cluster.remote.my_remote_cluster.seeds.0: remote_ip }
+
+  - do:
+      catch: bad_request
+      cluster.put_settings:
+        flat_settings: true
+        body:
+          transient:
+            cluster.remote.test_remote_cluster.simple.socket_connections: "20"
+            cluster.remote.test_remote_cluster.sniff.seeds: $remote_ip
+
+  - match: { status: 400 }
+  - match: { error.root_cause.0.type: "illegal_argument_exception" }
+  - match: { error.root_cause.0.reason: "Setting \"cluster.remote.test_remote_cluster.simple.socket_connections\" cannot be
+  used with the configured \"cluster.remote.test_remote_cluster.mode\" [required=SIMPLE, configured=SNIFF]" }
+
+  - do:
+      catch: bad_request
+      cluster.put_settings:
+        flat_settings: true
+        body:
+          transient:
+            cluster.remote.test_remote_cluster.simple.addresses: $remote_ip
+            cluster.remote.test_remote_cluster.sniff.seeds: $remote_ip
+
+  - match: { status: 400 }
+  - match: { error.root_cause.0.type: "illegal_argument_exception" }
+  - match: { error.root_cause.0.reason: "Setting \"cluster.remote.test_remote_cluster.simple.addresses\" cannot be
+   used with the configured \"cluster.remote.test_remote_cluster.mode\" [required=SIMPLE, configured=SNIFF]" }
+
+---
+"Add transient remote cluster using simple connection mode using valid settings":
+  - do:
+      cluster.get_settings:
+        include_defaults: true
+
+  - set: { defaults.cluster.remote.my_remote_cluster.seeds.0: remote_ip }
+
+  - do:
+      cluster.put_settings:
+        flat_settings: true
+        body:
+          transient:
+            cluster.remote.test_remote_cluster.mode: "simple"
+            cluster.remote.test_remote_cluster.simple.socket_connections: "3"
+            cluster.remote.test_remote_cluster.simple.addresses: $remote_ip
+
+  - match: {transient.cluster\.remote\.test_remote_cluster\.mode: "simple"}
+  - match: {transient.cluster\.remote\.test_remote_cluster\.simple\.socket_connections: "3"}
+  - match: {transient.cluster\.remote\.test_remote_cluster\.simple\.addresses: $remote_ip}
+
+  - do:
+      search:
+        rest_total_hits_as_int: true
+        index: test_remote_cluster:test_index
+
+  - is_false: num_reduce_phases
+  - match: {_clusters.total: 1}
+  - match: {_clusters.successful: 1}
+  - match: {_clusters.skipped: 0}
+  - match: { _shards.total: 3 }
+  - match: { hits.total: 6 }
+  - match: { hits.hits.0._index: "test_remote_cluster:test_index" }
+
+---
+"Add transient remote cluster using sniff connection mode using valid settings":
+  - do:
+      cluster.get_settings:
+        include_defaults: true
+
+  - set: { defaults.cluster.remote.my_remote_cluster.seeds.0: remote_ip }
+
+  - do:
+      cluster.put_settings:
+        flat_settings: true
+        body:
+          transient:
+            cluster.remote.test_remote_cluster.mode: "sniff"
+            cluster.remote.test_remote_cluster.sniff.node_connections: "3"
+            cluster.remote.test_remote_cluster.sniff.seeds: $remote_ip
+
+  - match: {transient.cluster\.remote\.test_remote_cluster\.mode: "sniff"}
+  - match: {transient.cluster\.remote\.test_remote_cluster\.sniff\.node_connections: "3"}
+  - match: {transient.cluster\.remote\.test_remote_cluster\.sniff\.seeds: $remote_ip}
+
+  - do:
+      search:
+        rest_total_hits_as_int: true
+        index: test_remote_cluster:test_index
+
+  - is_false: num_reduce_phases
+  - match: {_clusters.total: 1}
+  - match: {_clusters.successful: 1}
+  - match: {_clusters.skipped: 0}
+  - match: { _shards.total: 3 }
+  - match: { hits.total: 6 }
+  - match: { hits.hits.0._index: "test_remote_cluster:test_index" }
+
+---
+"Switch connection mode for configured cluster":
+  - do:
+      cluster.get_settings:
+        include_defaults: true
+
+  - set: { defaults.cluster.remote.my_remote_cluster.seeds.0: remote_ip }
+
+  - do:
+      cluster.put_settings:
+        flat_settings: true
+        body:
+          transient:
+            cluster.remote.test_remote_cluster.mode: "sniff"
+            cluster.remote.test_remote_cluster.sniff.seeds: $remote_ip
+
+  - match: {transient.cluster\.remote\.test_remote_cluster\.mode: "sniff"}
+  - match: {transient.cluster\.remote\.test_remote_cluster\.sniff\.seeds: $remote_ip}
+
+  - do:
+      search:
+        rest_total_hits_as_int: true
+        index: test_remote_cluster:test_index
+
+  - is_false: num_reduce_phases
+  - match: {_clusters.total: 1}
+  - match: {_clusters.successful: 1}
+  - match: {_clusters.skipped: 0}
+  - match: { _shards.total: 3 }
+  - match: { hits.total: 6 }
+  - match: { hits.hits.0._index: "test_remote_cluster:test_index" }
+
+  - do:
+      catch: bad_request
+      cluster.put_settings:
+        flat_settings: true
+        body:
+          transient:
+            cluster.remote.test_remote_cluster.mode: "simple"
+            cluster.remote.test_remote_cluster.simple.addresses: $remote_ip
+
+  - match: { status: 400 }
+  - match: { error.root_cause.0.type: "illegal_argument_exception" }
+  - match: { error.root_cause.0.reason: "Setting \"cluster.remote.test_remote_cluster.sniff.seeds\" cannot be
+  used with the configured \"cluster.remote.test_remote_cluster.mode\" [required=SNIFF, configured=SIMPLE]" }
+
+  - do:
+      cluster.put_settings:
+        flat_settings: true
+        body:
+          transient:
+            cluster.remote.test_remote_cluster.mode: "simple"
+            cluster.remote.test_remote_cluster.sniff.seeds: null
+            cluster.remote.test_remote_cluster.simple.addresses: $remote_ip
+
+  - match: {transient.cluster\.remote\.test_remote_cluster\.mode: "simple"}
+  - match: {transient.cluster\.remote\.test_remote_cluster\.simple\.addresses: $remote_ip}
+
+  - do:
+      search:
+        rest_total_hits_as_int: true
+        index: test_remote_cluster:test_index
+
+  - is_false: num_reduce_phases
+  - match: {_clusters.total: 1}
+  - match: {_clusters.successful: 1}
+  - match: {_clusters.skipped: 0}
+  - match: { _shards.total: 3 }
+  - match: { hits.total: 6 }
+  - match: { hits.hits.0._index: "test_remote_cluster:test_index" }

server/src/main/java/org/elasticsearch/common/settings/ClusterSettings.java

@@ -108,8 +108,10 @@
 import org.elasticsearch.search.aggregations.MultiBucketConsumerService;
 import org.elasticsearch.search.fetch.subphase.highlight.FastVectorHighlighter;
 import org.elasticsearch.threadpool.ThreadPool;
-import org.elasticsearch.transport.RemoteClusterAware;
 import org.elasticsearch.transport.RemoteClusterService;
+import org.elasticsearch.transport.RemoteConnectionStrategy;
+import org.elasticsearch.transport.SimpleConnectionStrategy;
+import org.elasticsearch.transport.SniffConnectionStrategy;
 import org.elasticsearch.transport.TransportSettings;
 import org.elasticsearch.watcher.ResourceWatcherService;
 
@@ -303,14 +305,8 @@ public void apply(Settings value, Settings current, Settings previous) {
             SearchService.DEFAULT_ALLOW_PARTIAL_SEARCH_RESULTS,
             ElectMasterService.DISCOVERY_ZEN_MINIMUM_MASTER_NODES_SETTING,
             TransportSearchAction.SHARD_COUNT_LIMIT_SETTING,
-            RemoteClusterAware.REMOTE_CLUSTERS_SEEDS,
-            RemoteClusterAware.SEARCH_REMOTE_CLUSTERS_SEEDS,
-            RemoteClusterAware.REMOTE_CLUSTERS_PROXY,
-            RemoteClusterAware.SEARCH_REMOTE_CLUSTERS_PROXY,
             RemoteClusterService.REMOTE_CLUSTER_SKIP_UNAVAILABLE,
             RemoteClusterService.SEARCH_REMOTE_CLUSTER_SKIP_UNAVAILABLE,
-            RemoteClusterService.REMOTE_CONNECTIONS_PER_CLUSTER,
-            RemoteClusterService.SEARCH_REMOTE_CONNECTIONS_PER_CLUSTER,
             RemoteClusterService.REMOTE_INITIAL_CONNECTION_TIMEOUT_SETTING,
             RemoteClusterService.SEARCH_REMOTE_INITIAL_CONNECTION_TIMEOUT_SETTING,
             RemoteClusterService.REMOTE_NODE_ATTRIBUTE,
@@ -319,6 +315,17 @@ public void apply(Settings value, Settings current, Settings previous) {
             RemoteClusterService.SEARCH_ENABLE_REMOTE_CLUSTERS,
             RemoteClusterService.REMOTE_CLUSTER_PING_SCHEDULE,
             RemoteClusterService.REMOTE_CLUSTER_COMPRESS,
+            RemoteConnectionStrategy.REMOTE_CONNECTION_MODE,
+            SimpleConnectionStrategy.REMOTE_CLUSTER_ADDRESSES,
+            SimpleConnectionStrategy.REMOTE_SOCKET_CONNECTIONS,
+            SniffConnectionStrategy.SEARCH_REMOTE_CLUSTERS_SEEDS,
+            SniffConnectionStrategy.SEARCH_REMOTE_CLUSTERS_PROXY,
+            SniffConnectionStrategy.SEARCH_REMOTE_CONNECTIONS_PER_CLUSTER,
+            SniffConnectionStrategy.REMOTE_CONNECTIONS_PER_CLUSTER,
+            SniffConnectionStrategy.REMOTE_CLUSTER_SEEDS_OLD,
+            SniffConnectionStrategy.REMOTE_CLUSTERS_PROXY,
+            SniffConnectionStrategy.REMOTE_CLUSTER_SEEDS,
+            SniffConnectionStrategy.REMOTE_NODE_CONNECTIONS,
             TransportCloseIndexAction.CLUSTER_INDICES_CLOSE_ENABLE_SETTING,
             ShardsLimitAllocationDecider.CLUSTER_TOTAL_SHARDS_PER_NODE_SETTING,
             NodeConnectionsService.CLUSTER_NODE_RECONNECT_INTERVAL_SETTING,
@@ -520,8 +527,8 @@ public void apply(Settings value, Settings current, Settings previous) {
             DiscoveryUpgradeService.ENABLE_UNSAFE_BOOTSTRAPPING_ON_UPGRADE_SETTING)));
 
     public static List<SettingUpgrader<?>> BUILT_IN_SETTING_UPGRADERS = Collections.unmodifiableList(Arrays.asList(
-            RemoteClusterAware.SEARCH_REMOTE_CLUSTER_SEEDS_UPGRADER,
-            RemoteClusterAware.SEARCH_REMOTE_CLUSTERS_PROXY_UPGRADER,
+            SniffConnectionStrategy.SEARCH_REMOTE_CLUSTER_SEEDS_UPGRADER,
+            SniffConnectionStrategy.SEARCH_REMOTE_CLUSTERS_PROXY_UPGRADER,
             RemoteClusterService.SEARCH_REMOTE_CLUSTER_SKIP_UNAVAILABLE_UPGRADER));
 
 }