SONAR-12686 Fix Elasticsearch properties for a single node

- https://www.elastic.co/guide/en/elasticsearch/reference/7.x/breaking-changes-7.0.html#_discovery_configuration_is_required_in_production

server/sonar-main/src/main/java/org/sonar/application/es/EsSettings.java

@@ -108,7 +108,9 @@ public class EsSettings {
       int searchPort = Integer.parseInt(props.nonNullValue(SEARCH_PORT.getKey()));
       builder.put(ES_HTTP_HOST_KEY, searchHost.getHostAddress());
       builder.put(ES_HTTP_PORT_KEY, valueOf(searchPort));
-      builder.put(ES_NETWORK_HOST_KEY, valueOf(searchHost.getHostAddress()));
+      builder.put(ES_NETWORK_HOST_KEY, searchHost.getHostAddress());
+      builder.put("discovery.seed_hosts", searchHost.getHostAddress());
+      builder.put("cluster.initial_master_nodes", searchHost.getHostAddress());
 
       int transportPort = Integer.parseInt(props.nonNullValue(ES_PORT.getKey()));
 

server/sonar-main/src/test/java/org/sonar/application/es/EsSettingsTest.java

@@ -150,14 +150,15 @@ public class EsSettingsTest {
       .containsEntry("http.host", "127.0.0.1")
       // no cluster, but cluster and node names are set though
       .containsEntry("cluster.name", "sonarqube")
-      .containsEntry("node.name", "sonarqube");
+      .containsEntry("node.name", "sonarqube")
+      .containsEntry("discovery.seed_hosts", "127.0.0.1")
+      .containsEntry("cluster.initial_master_nodes", "127.0.0.1");
 
     assertThat(generated.get("path.data")).isNotNull();
     assertThat(generated.get("path.logs")).isNotNull();
     assertThat(generated.get("path.home")).isNull();
     assertThat(generated.get("path.conf")).isNull();
 
-    assertThat(generated.get("discovery.seed_hosts")).isNull();
     assertThat(generated)
       .containsEntry("discovery.initial_state_timeout", "30s")
       .containsEntry("action.auto_create_index", "false");