add check for cases when cluster is offline

kafka-ui-api/src/main/java/com/provectus/kafka/ui/cluster/model/ClustersStorage.java

@@ -33,8 +33,8 @@ public class ClustersStorage {
 
     public KafkaCluster getClusterById(String clusterId) {
         return kafkaClusters.stream()
-                .filter(cluster -> cluster.getId().equals(clusterId))
+                .filter(cluster -> cluster.getId() != null && cluster.getId().equals(clusterId))
                 .findFirst()
-                .orElseThrow();
+                .orElse(null);
     }
 }

kafka-ui-api/src/main/java/com/provectus/kafka/ui/cluster/service/ClusterService.java

@@ -30,27 +30,32 @@ public class ClusterService {
     }
 
     public Mono<ResponseEntity<BrokersMetrics>> getBrokersMetrics(String clusterId) {
-        return Mono.just(ResponseEntity.ok(clustersStorage.getClusterById(clusterId).getBrokersMetrics()));
+        KafkaCluster cluster = clustersStorage.getClusterById(clusterId);
+        if (cluster == null) return null;
+        return Mono.just(ResponseEntity.ok(cluster.getBrokersMetrics()));
     }
 
     public Mono<ResponseEntity<Flux<Topic>>> getTopics(String clusterId) {
         KafkaCluster cluster = clustersStorage.getClusterById(clusterId);
-
+        if (cluster == null) return null;
         return Mono.just(ResponseEntity.ok(Flux.fromIterable(cluster.getTopics())));
     }
 
     public Mono<ResponseEntity<TopicDetails>> getTopicDetails(String clusterId, String topicName) {
         KafkaCluster cluster = clustersStorage.getClusterById(clusterId);
+        if (cluster == null) return null;
         return Mono.just(ResponseEntity.ok(cluster.getTopicDetails(topicName)));
     }
 
     public Mono<ResponseEntity<Flux<TopicConfig>>> getTopicConfigs(String clusterId, String topicName) {
         KafkaCluster cluster = clustersStorage.getClusterById(clusterId);
+        if (cluster == null) return null;
         return Mono.just(ResponseEntity.ok(Flux.fromIterable(cluster.getTopicConfigsMap().get(topicName))));
     }
 
     public Mono<ResponseEntity<Topic>> createTopic(String clusterId, Mono<TopicFormData> topicFormData) {
         KafkaCluster cluster = clustersStorage.getClusterById(clusterId);
+        if (cluster == null) return null;
         return kafkaService.createTopic(cluster, topicFormData);
     }
 }

kafka-ui-api/src/main/java/com/provectus/kafka/ui/kafka/KafkaService.java

@@ -42,19 +42,48 @@ public class KafkaService {
             return;
         }
 
-        kafkaCluster.setId(kafkaCluster.getAdminClient().describeCluster().clusterId().get());
-        kafkaCluster.getCluster().setId(kafkaCluster.getAdminClient().describeCluster().clusterId().get());
+        kafkaCluster.getCluster().setId(kafkaCluster.getId());
         kafkaCluster.getCluster().setStatus(ServerStatus.ONLINE);
         loadMetrics(kafkaCluster);
         loadTopicsData(kafkaCluster);
     }
 
+
+    @SneakyThrows
+    public Mono<ResponseEntity<Topic>> createTopic(KafkaCluster cluster, Mono<TopicFormData> topicFormData) {
+        return topicFormData.flatMap(
+                topicData -> {
+                    AdminClient adminClient = cluster.getAdminClient();
+                    NewTopic newTopic = new NewTopic(topicData.getName(), topicData.getPartitions(), topicData.getReplicationFactor().shortValue());
+                    newTopic.configs(topicData.getConfigs());
+
+                    createTopic(adminClient, newTopic);
+
+                    DescribeTopicsResult topicDescriptionsWrapper = adminClient.describeTopics(Collections.singletonList(topicData.getName()));
+                    Map<String, KafkaFuture<TopicDescription>> topicDescriptionFuturesMap = topicDescriptionsWrapper.values();
+                    var entry = topicDescriptionFuturesMap.entrySet().iterator().next();
+                    var topicDescription = getTopicDescription(entry);
+                    if (topicDescription == null) return Mono.error(new RuntimeException("Can't find created topic"));
+
+                    Topic topic = collectTopicData(cluster, topicDescription);
+                    cluster.getTopics().add(topic);
+                    return Mono.just(new ResponseEntity<>(topic, HttpStatus.CREATED));
+                }
+        );
+    }
+
+    @SneakyThrows
+    private String getClusterId(KafkaCluster kafkaCluster) {
+        return kafkaCluster.getAdminClient().describeCluster().clusterId().get();
+    }
+
     private boolean createAdminClient(KafkaCluster kafkaCluster) {
         try {
             Properties properties = new Properties();
             properties.put(AdminClientConfig.BOOTSTRAP_SERVERS_CONFIG, kafkaCluster.getBootstrapServers());
             properties.put(AdminClientConfig.REQUEST_TIMEOUT_MS_CONFIG, 5000);
             kafkaCluster.setAdminClient(AdminClient.create(properties));
+            kafkaCluster.setId(getClusterId(kafkaCluster));
 
             return true;
         } catch (Exception e) {
@@ -67,7 +96,7 @@ public class KafkaService {
 
     private boolean isAdminClientConnected(KafkaCluster kafkaCluster) {
         try {
-            kafkaCluster.getAdminClient().listTopics();
+            getClusterId(kafkaCluster);
 
             return true;
         } catch (Exception e) {
@@ -221,29 +250,6 @@ public class KafkaService {
         kafkaCluster.getTopicConfigsMap().put(topicName, topicConfigs);
     }
 
-    @SneakyThrows
-    public Mono<ResponseEntity<Topic>> createTopic(KafkaCluster cluster, Mono<TopicFormData> topicFormData) {
-        return topicFormData.flatMap(
-                topicData -> {
-                    AdminClient adminClient = cluster.getAdminClient();
-                    NewTopic newTopic = new NewTopic(topicData.getName(), topicData.getPartitions(), topicData.getReplicationFactor().shortValue());
-                    newTopic.configs(topicData.getConfigs());
-
-                    createTopic(adminClient, newTopic);
-
-                    DescribeTopicsResult topicDescriptionsWrapper = adminClient.describeTopics(Collections.singletonList(topicData.getName()));
-                    Map<String, KafkaFuture<TopicDescription>> topicDescriptionFuturesMap = topicDescriptionsWrapper.values();
-                    var entry = topicDescriptionFuturesMap.entrySet().iterator().next();
-                    var topicDescription = getTopicDescription(entry);
-                    if (topicDescription == null) return Mono.error(new RuntimeException("Can't find created topic"));
-
-                    Topic topic = collectTopicData(cluster, topicDescription);
-                    cluster.getTopics().add(topic);
-                    return Mono.just(new ResponseEntity<>(topic, HttpStatus.CREATED));
-                }
-        );
-    }
-
     @SneakyThrows
     private void createTopic(AdminClient adminClient, NewTopic newTopic) {
         adminClient.createTopics(Collections.singletonList(newTopic))