Consumer groups pagination (Backend) (#1318)

* consumer-groups endpoint with pagination added
* consumer group dto mappings moved to controller
* consumer groups loading logic refactored

kafka-ui-api/src/main/java/com/provectus/kafka/ui/controller/ConsumerGroupsController.java

@@ -4,16 +4,21 @@ import static java.util.stream.Collectors.toMap;
 
 import com.provectus.kafka.ui.api.ConsumerGroupsApi;
 import com.provectus.kafka.ui.exception.ValidationException;
+import com.provectus.kafka.ui.mapper.ConsumerGroupMapper;
 import com.provectus.kafka.ui.model.ConsumerGroupDTO;
 import com.provectus.kafka.ui.model.ConsumerGroupDetailsDTO;
 import com.provectus.kafka.ui.model.ConsumerGroupOffsetsResetDTO;
+import com.provectus.kafka.ui.model.ConsumerGroupOrderingDTO;
+import com.provectus.kafka.ui.model.ConsumerGroupsPageResponseDTO;
 import com.provectus.kafka.ui.model.PartitionOffsetDTO;
 import com.provectus.kafka.ui.service.ConsumerGroupService;
 import com.provectus.kafka.ui.service.OffsetsResetService;
 import java.util.Map;
 import java.util.Optional;
+import java.util.stream.Collectors;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
+import org.springframework.beans.factory.annotation.Value;
 import org.springframework.http.ResponseEntity;
 import org.springframework.util.CollectionUtils;
 import org.springframework.web.bind.annotation.RestController;
@@ -29,17 +34,21 @@ public class ConsumerGroupsController extends AbstractController implements Cons
   private final ConsumerGroupService consumerGroupService;
   private final OffsetsResetService offsetsResetService;
 
+  @Value("${consumer.groups.page.size:25}")
+  private int defaultConsumerGroupsPageSize;
+
   @Override
   public Mono<ResponseEntity<Void>> deleteConsumerGroup(String clusterName, String id,
                                                         ServerWebExchange exchange) {
     return consumerGroupService.deleteConsumerGroupById(getCluster(clusterName), id)
-        .map(ResponseEntity::ok);
+        .thenReturn(ResponseEntity.ok().build());
   }
 
   @Override
   public Mono<ResponseEntity<ConsumerGroupDetailsDTO>> getConsumerGroup(
       String clusterName, String consumerGroupId, ServerWebExchange exchange) {
     return consumerGroupService.getConsumerGroupDetail(getCluster(clusterName), consumerGroupId)
+        .map(ConsumerGroupMapper::toDetailsDto)
         .map(ResponseEntity::ok);
   }
 
@@ -47,8 +56,9 @@ public class ConsumerGroupsController extends AbstractController implements Cons
   @Override
   public Mono<ResponseEntity<Flux<ConsumerGroupDTO>>> getConsumerGroups(String clusterName,
                                                                      ServerWebExchange exchange) {
-    return consumerGroupService.getConsumerGroups(getCluster(clusterName))
+    return consumerGroupService.getAllConsumerGroups(getCluster(clusterName))
         .map(Flux::fromIterable)
+        .map(f -> f.map(ConsumerGroupMapper::toDto))
         .map(ResponseEntity::ok)
         .switchIfEmpty(Mono.just(ResponseEntity.notFound().build()));
   }
@@ -56,13 +66,41 @@ public class ConsumerGroupsController extends AbstractController implements Cons
   @Override
   public Mono<ResponseEntity<Flux<ConsumerGroupDTO>>> getTopicConsumerGroups(
       String clusterName, String topicName, ServerWebExchange exchange) {
-    return consumerGroupService.getConsumerGroups(
-        getCluster(clusterName), Optional.of(topicName))
+    return consumerGroupService.getConsumerGroupsForTopic(getCluster(clusterName), topicName)
         .map(Flux::fromIterable)
+        .map(f -> f.map(ConsumerGroupMapper::toDto))
         .map(ResponseEntity::ok)
         .switchIfEmpty(Mono.just(ResponseEntity.notFound().build()));
   }
 
+  @Override
+  public Mono<ResponseEntity<ConsumerGroupsPageResponseDTO>> getConsumerGroupsPage(
+      String clusterName,
+      Integer page,
+      Integer perPage,
+      String search,
+      ConsumerGroupOrderingDTO orderBy,
+      ServerWebExchange exchange) {
+    return consumerGroupService.getConsumerGroupsPage(
+            getCluster(clusterName),
+            Optional.ofNullable(page).filter(i -> i > 0).orElse(1),
+            Optional.ofNullable(perPage).filter(i -> i > 0).orElse(defaultConsumerGroupsPageSize),
+            search,
+            Optional.ofNullable(orderBy).orElse(ConsumerGroupOrderingDTO.NAME)
+        )
+        .map(this::convertPage)
+        .map(ResponseEntity::ok);
+  }
+
+  private ConsumerGroupsPageResponseDTO convertPage(ConsumerGroupService.ConsumerGroupsPage
+                                                    consumerGroupConsumerGroupsPage) {
+    return new ConsumerGroupsPageResponseDTO()
+        .pageCount(consumerGroupConsumerGroupsPage.getTotalPages())
+        .consumerGroups(consumerGroupConsumerGroupsPage.getConsumerGroups()
+            .stream()
+            .map(ConsumerGroupMapper::toDto)
+            .collect(Collectors.toList()));
+  }
 
   @Override
   public Mono<ResponseEntity<Void>> resetConsumerGroupOffsets(String clusterName, String group,

kafka-ui-api/src/main/java/com/provectus/kafka/ui/mapper/ConsumerGroupMapper.java

@@ -0,0 +1,112 @@
+package com.provectus.kafka.ui.mapper;
+
+import com.provectus.kafka.ui.model.BrokerDTO;
+import com.provectus.kafka.ui.model.ConsumerGroupDTO;
+import com.provectus.kafka.ui.model.ConsumerGroupDetailsDTO;
+import com.provectus.kafka.ui.model.ConsumerGroupStateDTO;
+import com.provectus.kafka.ui.model.ConsumerGroupTopicPartitionDTO;
+import com.provectus.kafka.ui.model.InternalConsumerGroup;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Optional;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+import org.apache.kafka.common.Node;
+import org.apache.kafka.common.TopicPartition;
+
+public class ConsumerGroupMapper {
+
+  public static ConsumerGroupDTO toDto(InternalConsumerGroup c) {
+    return convertToConsumerGroup(c, new ConsumerGroupDTO());
+  }
+
+  public static ConsumerGroupDetailsDTO toDetailsDto(InternalConsumerGroup g) {
+    ConsumerGroupDetailsDTO details = convertToConsumerGroup(g, new ConsumerGroupDetailsDTO());
+    Map<TopicPartition, ConsumerGroupTopicPartitionDTO> partitionMap = new HashMap<>();
+
+    for (Map.Entry<TopicPartition, Long> entry : g.getOffsets().entrySet()) {
+      ConsumerGroupTopicPartitionDTO partition = new ConsumerGroupTopicPartitionDTO();
+      partition.setTopic(entry.getKey().topic());
+      partition.setPartition(entry.getKey().partition());
+      partition.setCurrentOffset(entry.getValue());
+
+      final Optional<Long> endOffset = Optional.ofNullable(g.getEndOffsets())
+          .map(o -> o.get(entry.getKey()));
+
+      final Long behind = endOffset.map(o -> o - entry.getValue())
+          .orElse(0L);
+
+      partition.setEndOffset(endOffset.orElse(0L));
+      partition.setMessagesBehind(behind);
+
+      partitionMap.put(entry.getKey(), partition);
+    }
+
+    for (InternalConsumerGroup.InternalMember member : g.getMembers()) {
+      for (TopicPartition topicPartition : member.getAssignment()) {
+        final ConsumerGroupTopicPartitionDTO partition = partitionMap.computeIfAbsent(
+            topicPartition,
+            (tp) -> new ConsumerGroupTopicPartitionDTO()
+                .topic(tp.topic())
+                .partition(tp.partition())
+        );
+        partition.setHost(member.getHost());
+        partition.setConsumerId(member.getConsumerId());
+        partitionMap.put(topicPartition, partition);
+      }
+    }
+    details.setPartitions(new ArrayList<>(partitionMap.values()));
+    return details;
+  }
+
+  private static <T extends ConsumerGroupDTO> T convertToConsumerGroup(
+      InternalConsumerGroup c, T consumerGroup) {
+    consumerGroup.setGroupId(c.getGroupId());
+    consumerGroup.setMembers(c.getMembers().size());
+
+    int numTopics = Stream.concat(
+        c.getOffsets().keySet().stream().map(TopicPartition::topic),
+        c.getMembers().stream()
+            .flatMap(m -> m.getAssignment().stream().map(TopicPartition::topic))
+    ).collect(Collectors.toSet()).size();
+
+    long messagesBehind = c.getOffsets().entrySet().stream()
+        .mapToLong(e ->
+            Optional.ofNullable(c.getEndOffsets())
+                .map(o -> o.get(e.getKey()))
+                .map(o -> o - e.getValue())
+                .orElse(0L)
+        ).sum();
+
+    consumerGroup.setMessagesBehind(messagesBehind);
+    consumerGroup.setTopics(numTopics);
+    consumerGroup.setSimple(c.isSimple());
+
+    Optional.ofNullable(c.getState())
+        .ifPresent(s -> consumerGroup.setState(mapConsumerGroupState(s)));
+    Optional.ofNullable(c.getCoordinator())
+        .ifPresent(cd -> consumerGroup.setCoordinator(mapCoordinator(cd)));
+
+    consumerGroup.setPartitionAssignor(c.getPartitionAssignor());
+    return consumerGroup;
+  }
+
+  private static BrokerDTO mapCoordinator(Node node) {
+    return new BrokerDTO().host(node.host()).id(node.id());
+  }
+
+  private static ConsumerGroupStateDTO mapConsumerGroupState(
+      org.apache.kafka.common.ConsumerGroupState state) {
+    switch (state) {
+      case DEAD: return ConsumerGroupStateDTO.DEAD;
+      case EMPTY: return ConsumerGroupStateDTO.EMPTY;
+      case STABLE: return ConsumerGroupStateDTO.STABLE;
+      case PREPARING_REBALANCE: return ConsumerGroupStateDTO.PREPARING_REBALANCE;
+      case COMPLETING_REBALANCE: return ConsumerGroupStateDTO.COMPLETING_REBALANCE;
+      default: return ConsumerGroupStateDTO.UNKNOWN;
+    }
+  }
+
+
+}

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

@@ -2,10 +2,13 @@ package com.provectus.kafka.ui.model;
 
 import java.util.Collection;
 import java.util.Map;
+import java.util.Optional;
 import java.util.Set;
+import java.util.function.Predicate;
+import java.util.stream.Collectors;
 import lombok.Builder;
 import lombok.Data;
-import org.apache.kafka.clients.consumer.OffsetAndMetadata;
+import org.apache.kafka.clients.admin.ConsumerGroupDescription;
 import org.apache.kafka.common.ConsumerGroupState;
 import org.apache.kafka.common.Node;
 import org.apache.kafka.common.TopicPartition;
@@ -16,7 +19,7 @@ public class InternalConsumerGroup {
   private final String groupId;
   private final boolean simple;
   private final Collection<InternalMember> members;
-  private final Map<TopicPartition, OffsetAndMetadata> offsets;
+  private final Map<TopicPartition, Long> offsets;
   private final Map<TopicPartition, Long> endOffsets;
   private final String partitionAssignor;
   private final ConsumerGroupState state;
@@ -31,4 +34,61 @@ public class InternalConsumerGroup {
     private final String host;
     private final Set<TopicPartition> assignment;
   }
+
+  public static InternalConsumerGroup create(
+      ConsumerGroupDescription description, 
+      Map<TopicPartition, Long> groupOffsets,
+      Map<TopicPartition, Long> topicEndOffsets) {
+    var builder = InternalConsumerGroup.builder();
+    builder.groupId(description.groupId());
+    builder.simple(description.isSimpleConsumerGroup());
+    builder.state(description.state());
+    builder.partitionAssignor(description.partitionAssignor());
+    builder.members(
+        description.members().stream()
+            .map(m ->
+                InternalConsumerGroup.InternalMember.builder()
+                    .assignment(m.assignment().topicPartitions())
+                    .clientId(m.clientId())
+                    .groupInstanceId(m.groupInstanceId().orElse(""))
+                    .consumerId(m.consumerId())
+                    .clientId(m.clientId())
+                    .host(m.host())
+                    .build()
+            ).collect(Collectors.toList())
+    );
+    builder.offsets(groupOffsets);
+    builder.endOffsets(topicEndOffsets);
+    Optional.ofNullable(description.coordinator()).ifPresent(builder::coordinator);
+    return builder.build();
+  }
+
+  // removes data for all partitions that are not fit filter
+  public InternalConsumerGroup retainDataForPartitions(Predicate<TopicPartition> partitionsFilter) {
+    var offsets = getOffsets().entrySet().stream()
+        .filter(e -> partitionsFilter.test(e.getKey()))
+        .collect(Collectors.toMap(
+            Map.Entry::getKey,
+            Map.Entry::getValue
+        ));
+
+    var members = getMembers().stream()
+        .map(m -> filterConsumerMemberTopic(m, partitionsFilter))
+        .filter(m -> !m.getAssignment().isEmpty())
+        .collect(Collectors.toList());
+
+    return toBuilder()
+        .offsets(offsets)
+        .members(members)
+        .build();
+  }
+
+  private InternalConsumerGroup.InternalMember filterConsumerMemberTopic(
+      InternalConsumerGroup.InternalMember member, Predicate<TopicPartition> partitionsFilter) {
+    var topicPartitions = member.getAssignment()
+        .stream()
+        .filter(partitionsFilter)
+        .collect(Collectors.toSet());
+    return member.toBuilder().assignment(topicPartitions).build();
+  }
 }

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

@@ -1,21 +1,22 @@
 package com.provectus.kafka.ui.service;
 
-import com.provectus.kafka.ui.model.ConsumerGroupDTO;
-import com.provectus.kafka.ui.model.ConsumerGroupDetailsDTO;
+import com.provectus.kafka.ui.model.ConsumerGroupOrderingDTO;
 import com.provectus.kafka.ui.model.InternalConsumerGroup;
 import com.provectus.kafka.ui.model.KafkaCluster;
-import com.provectus.kafka.ui.util.ClusterUtil;
-import java.util.Collection;
-import java.util.Collections;
+import java.util.ArrayList;
+import java.util.Comparator;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
-import java.util.Optional;
 import java.util.Properties;
-import java.util.Set;
 import java.util.UUID;
+import java.util.function.Function;
 import java.util.stream.Collectors;
+import javax.annotation.Nullable;
 import lombok.RequiredArgsConstructor;
+import lombok.Value;
+import org.apache.commons.lang3.StringUtils;
+import org.apache.kafka.clients.admin.ConsumerGroupDescription;
 import org.apache.kafka.clients.admin.OffsetSpec;
 import org.apache.kafka.clients.consumer.ConsumerConfig;
 import org.apache.kafka.clients.consumer.KafkaConsumer;
@@ -25,6 +26,8 @@ import org.apache.kafka.common.utils.Bytes;
 import org.springframework.stereotype.Service;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
+import reactor.util.function.Tuple2;
+import reactor.util.function.Tuples;
 
 
 @Service
@@ -33,88 +36,145 @@ public class ConsumerGroupService {
 
   private final AdminClientService adminClientService;
 
-  private Mono<List<InternalConsumerGroup>> getConsumerGroupsInternal(KafkaCluster cluster) {
-    return adminClientService.get(cluster).flatMap(ac ->
-        ac.listConsumerGroups()
-            .flatMap(groupIds -> getConsumerGroupsInternal(cluster, groupIds)));
+  private Mono<List<InternalConsumerGroup>> getConsumerGroups(
+      ReactiveAdminClient ac,
+      List<ConsumerGroupDescription> descriptions) {
+    return Flux.fromIterable(descriptions)
+        // 1. getting committed offsets for all groups
+        .flatMap(desc -> ac.listConsumerGroupOffsets(desc.groupId())
+            .map(offsets -> Tuples.of(desc, offsets)))
+        .collectMap(Tuple2::getT1, Tuple2::getT2)
+        .flatMap((Map<ConsumerGroupDescription, Map<TopicPartition, Long>> groupOffsetsMap) -> {
+          var tpsFromGroupOffsets = groupOffsetsMap.values().stream()
+              .flatMap(v -> v.keySet().stream())
+              .collect(Collectors.toSet());
+          // 2. getting end offsets for partitions with in committed offsets
+          return ac.listOffsets(tpsFromGroupOffsets, OffsetSpec.latest())
+              .map(endOffsets ->
+                  descriptions.stream()
+                      .map(desc -> {
+                        var groupOffsets = groupOffsetsMap.get(desc);
+                        var endOffsetsForGroup = new HashMap<>(endOffsets);
+                        endOffsetsForGroup.keySet().retainAll(groupOffsets.keySet());
+                        // 3. gathering description & offsets
+                        return InternalConsumerGroup.create(desc, groupOffsets, endOffsetsForGroup);
+                      })
+                      .collect(Collectors.toList()));
+        });
   }
 
-  private Mono<List<InternalConsumerGroup>> getConsumerGroupsInternal(KafkaCluster cluster,
-                                                                     List<String> groupIds) {
-    return adminClientService.get(cluster).flatMap(ac ->
-        ac.describeConsumerGroups(groupIds)
-            .map(Map::values)
-            .flatMap(descriptions ->
-                Flux.fromIterable(descriptions)
-                    .parallel()
-                    .flatMap(d ->
-                        ac.listConsumerGroupOffsets(d.groupId())
-                            .map(offsets -> ClusterUtil.convertToInternalConsumerGroup(d, offsets))
-                    )
-                    .sequential()
-                    .collectList()));
+  @Deprecated // need to migrate to pagination
+  public Mono<List<InternalConsumerGroup>> getAllConsumerGroups(KafkaCluster cluster) {
+    return adminClientService.get(cluster)
+        .flatMap(ac -> describeConsumerGroups(ac, null)
+            .flatMap(descriptions -> getConsumerGroups(ac, descriptions)));
   }
 
-  public Mono<List<InternalConsumerGroup>> getConsumerGroups(
-      KafkaCluster cluster, Optional<String> topic, List<String> groupIds) {
-    final Mono<List<InternalConsumerGroup>> consumerGroups;
-
-    if (groupIds.isEmpty()) {
-      consumerGroups = getConsumerGroupsInternal(cluster);
-    } else {
-      consumerGroups = getConsumerGroupsInternal(cluster, groupIds);
-    }
-
-    return consumerGroups.flatMap(c -> {
-      final List<InternalConsumerGroup> groups = c.stream()
-              .map(d -> ClusterUtil.filterConsumerGroupTopic(d, topic))
-              .filter(Optional::isPresent)
-              .map(Optional::get)
-              .collect(Collectors.toList());
-
-      final Set<TopicPartition> topicPartitions =
-              groups.stream().flatMap(g -> g.getOffsets().keySet().stream())
-                  .collect(Collectors.toSet());
-
-      return topicPartitionsEndOffsets(cluster, topicPartitions).map(offsets ->
-          groups.stream().map(g -> {
-            Map<TopicPartition, Long> offsetsCopy = new HashMap<>(offsets);
-            offsetsCopy.keySet().retainAll(g.getOffsets().keySet());
-            return g.toBuilder().endOffsets(offsetsCopy).build();
-          }).collect(Collectors.toList())
-      );
-    });
+  public Mono<List<InternalConsumerGroup>> getConsumerGroupsForTopic(KafkaCluster cluster,
+                                                                     String topic) {
+    return adminClientService.get(cluster)
+        // 1. getting topic's end offsets
+        .flatMap(ac -> ac.listOffsets(topic, OffsetSpec.latest())
+            .flatMap(endOffsets -> {
+              var tps = new ArrayList<>(endOffsets.keySet());
+              // 2. getting all consumer groups
+              return ac.listConsumerGroups()
+                  .flatMap((List<String> groups) ->
+                      Flux.fromIterable(groups)
+                          // 3. for each group trying to find committed offsets for topic
+                          .flatMap(g ->
+                              ac.listConsumerGroupOffsets(g, tps)
+                                  .map(offsets -> Tuples.of(g, offsets)))
+                          .filter(t -> !t.getT2().isEmpty())
+                          .collectMap(Tuple2::getT1, Tuple2::getT2)
+                  )
+                  .flatMap((Map<String, Map<TopicPartition, Long>> groupOffsets) ->
+                      // 4. getting description for groups with non-emtpy offsets
+                      ac.describeConsumerGroups(new ArrayList<>(groupOffsets.keySet()))
+                          .map((Map<String, ConsumerGroupDescription> descriptions) ->
+                              descriptions.values().stream().map(desc ->
+                                      // 5. gathering and filter non-target-topic data
+                                      InternalConsumerGroup.create(
+                                              desc, groupOffsets.get(desc.groupId()), endOffsets)
+                                          .retainDataForPartitions(p -> p.topic().equals(topic))
+                                  )
+                                  .collect(Collectors.toList())));
+            }));
   }
 
-  public Mono<List<ConsumerGroupDTO>> getConsumerGroups(KafkaCluster cluster) {
-    return getConsumerGroups(cluster, Optional.empty());
+  @Value
+  public static class ConsumerGroupsPage {
+    List<InternalConsumerGroup> consumerGroups;
+    int totalPages;
   }
 
-  public Mono<List<ConsumerGroupDTO>> getConsumerGroups(KafkaCluster cluster,
-                                                        Optional<String> topic) {
-    return getConsumerGroups(cluster, topic, Collections.emptyList())
-        .map(c ->
-            c.stream().map(ClusterUtil::convertToConsumerGroup).collect(Collectors.toList())
-        );
+  public Mono<ConsumerGroupsPage> getConsumerGroupsPage(
+      KafkaCluster cluster,
+      int page,
+      int perPage,
+      @Nullable String search,
+      ConsumerGroupOrderingDTO orderBy) {
+    return adminClientService.get(cluster).flatMap(ac ->
+        describeConsumerGroups(ac, search).flatMap(descriptions ->
+            getConsumerGroups(
+                ac,
+                descriptions.stream()
+                    .sorted(getPaginationComparator(orderBy))
+                    .skip((long) (page - 1) * perPage)
+                    .limit(perPage)
+                    .collect(Collectors.toList())
+            ).map(cgs -> new ConsumerGroupsPage(
+                cgs,
+                (descriptions.size() / perPage) + (descriptions.size() % perPage == 0 ? 0 : 1))))
+    );
   }
 
-  private Mono<Map<TopicPartition, Long>> topicPartitionsEndOffsets(
-      KafkaCluster cluster, Collection<TopicPartition> topicPartitions) {
+  private Comparator<ConsumerGroupDescription> getPaginationComparator(ConsumerGroupOrderingDTO
+                                                                           orderBy) {
+    switch (orderBy) {
+      case NAME:
+        return Comparator.comparing(ConsumerGroupDescription::groupId);
+      case STATE:
+        Function<ConsumerGroupDescription, Integer> statesPriorities = cg -> {
+          switch (cg.state()) {
+            case STABLE: return 0;
+            case COMPLETING_REBALANCE: return 1;
+            case PREPARING_REBALANCE: return 2;
+            case EMPTY: return 3;
+            case DEAD: return 4;
+            case UNKNOWN: return 5;
+            default: return 100;
+          }
+        };
+        return Comparator.comparingInt(statesPriorities::apply);
+      case MEMBERS:
+        return Comparator.comparingInt(cg -> -cg.members().size());
+      default:
+        throw new IllegalStateException("Unsupported order by: " + orderBy);
+    }
+  }
 
-    return adminClientService.get(cluster).flatMap(ac ->
-        ac.listOffsets(topicPartitions, OffsetSpec.latest())
-    );
+  private Mono<List<ConsumerGroupDescription>> describeConsumerGroups(ReactiveAdminClient ac,
+                                                                      @Nullable String search) {
+    return ac.listConsumerGroups()
+        .map(groupIds -> groupIds
+            .stream()
+            .filter(groupId -> search == null || StringUtils.containsIgnoreCase(groupId, search))
+            .collect(Collectors.toList()))
+        .flatMap(ac::describeConsumerGroups)
+        .map(cgs -> new ArrayList<>(cgs.values()));
   }
 
-  public Mono<ConsumerGroupDetailsDTO> getConsumerGroupDetail(KafkaCluster cluster,
-                                                              String consumerGroupId) {
-    return getConsumerGroups(
-        cluster,
-        Optional.empty(),
-        Collections.singletonList(consumerGroupId)
-    ).filter(groups -> !groups.isEmpty()).map(groups -> groups.get(0)).map(
-        ClusterUtil::convertToConsumerGroupDetails
-    );
+  public Mono<InternalConsumerGroup> getConsumerGroupDetail(KafkaCluster cluster,
+                                                            String consumerGroupId) {
+    return adminClientService.get(cluster)
+        .flatMap(ac -> ac.describeConsumerGroups(List.of(consumerGroupId))
+            .filter(m -> m.containsKey(consumerGroupId))
+            .map(r -> r.get(consumerGroupId))
+            .flatMap(descr ->
+                getConsumerGroups(ac, List.of(descr))
+                    .filter(groups -> !groups.isEmpty())
+                    .map(groups -> groups.get(0))));
   }
 
   public Mono<Void> deleteConsumerGroupById(KafkaCluster cluster,

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

@@ -31,6 +31,7 @@ import org.apache.kafka.clients.admin.ConfigEntry;
 import org.apache.kafka.clients.admin.ConsumerGroupDescription;
 import org.apache.kafka.clients.admin.ConsumerGroupListing;
 import org.apache.kafka.clients.admin.DescribeConfigsOptions;
+import org.apache.kafka.clients.admin.ListConsumerGroupOffsetsOptions;
 import org.apache.kafka.clients.admin.ListTopicsOptions;
 import org.apache.kafka.clients.admin.NewPartitionReassignment;
 import org.apache.kafka.clients.admin.NewPartitions;
@@ -293,9 +294,23 @@ public class ReactiveAdminClient implements Closeable {
     return toMono(client.describeConsumerGroups(groupIds).all());
   }
 
-  public Mono<Map<TopicPartition, OffsetAndMetadata>> listConsumerGroupOffsets(String groupId) {
-    return toMono(client.listConsumerGroupOffsets(groupId).partitionsToOffsetAndMetadata())
-        .map(MapUtil::removeNullValues);
+  public Mono<Map<TopicPartition, Long>> listConsumerGroupOffsets(String groupId) {
+    return listConsumerGroupOffsets(groupId, new ListConsumerGroupOffsetsOptions());
+  }
+
+  public Mono<Map<TopicPartition, Long>> listConsumerGroupOffsets(
+      String groupId, List<TopicPartition> partitions) {
+    return listConsumerGroupOffsets(groupId,
+        new ListConsumerGroupOffsetsOptions().topicPartitions(partitions));
+  }
+
+  private Mono<Map<TopicPartition, Long>> listConsumerGroupOffsets(
+      String groupId, ListConsumerGroupOffsetsOptions options) {
+    return toMono(client.listConsumerGroupOffsets(groupId, options).partitionsToOffsetAndMetadata())
+        .map(MapUtil::removeNullValues)
+        .map(m -> m.entrySet().stream()
+            .map(e -> Tuples.of(e.getKey(), e.getValue().offset()))
+            .collect(Collectors.toMap(Tuple2::getT1, Tuple2::getT2)));
   }
 
   public Mono<Void> alterConsumerGroupOffsets(String groupId, Map<TopicPartition, Long> offsets) {

kafka-ui-api/src/main/java/com/provectus/kafka/ui/util/ClusterUtil.java

@@ -1,11 +1,5 @@
 package com.provectus.kafka.ui.util;
 
-import com.provectus.kafka.ui.model.BrokerDTO;
-import com.provectus.kafka.ui.model.ConsumerGroupDTO;
-import com.provectus.kafka.ui.model.ConsumerGroupDetailsDTO;
-import com.provectus.kafka.ui.model.ConsumerGroupStateDTO;
-import com.provectus.kafka.ui.model.ConsumerGroupTopicPartitionDTO;
-import com.provectus.kafka.ui.model.InternalConsumerGroup;
 import com.provectus.kafka.ui.model.MessageFormatDTO;
 import com.provectus.kafka.ui.model.ServerStatusDTO;
 import com.provectus.kafka.ui.model.TopicMessageDTO;
@@ -13,20 +7,10 @@ import com.provectus.kafka.ui.serde.RecordSerDe;
 import java.time.Instant;
 import java.time.OffsetDateTime;
 import java.time.ZoneId;
-import java.util.ArrayList;
-import java.util.Collection;
 import java.util.HashMap;
 import java.util.Map;
-import java.util.Optional;
-import java.util.Set;
-import java.util.stream.Collectors;
-import java.util.stream.Stream;
 import lombok.extern.slf4j.Slf4j;
-import org.apache.kafka.clients.admin.ConsumerGroupDescription;
 import org.apache.kafka.clients.consumer.ConsumerRecord;
-import org.apache.kafka.clients.consumer.OffsetAndMetadata;
-import org.apache.kafka.common.Node;
-import org.apache.kafka.common.TopicPartition;
 import org.apache.kafka.common.record.TimestampType;
 import org.apache.kafka.common.utils.Bytes;
 
@@ -36,123 +20,6 @@ public class ClusterUtil {
 
   private static final ZoneId UTC_ZONE_ID = ZoneId.of("UTC");
 
-  public static InternalConsumerGroup convertToInternalConsumerGroup(
-      ConsumerGroupDescription description, Map<TopicPartition, OffsetAndMetadata> offsets) {
-
-    var builder = InternalConsumerGroup.builder();
-    builder.groupId(description.groupId());
-    builder.simple(description.isSimpleConsumerGroup());
-    builder.state(description.state());
-    builder.partitionAssignor(description.partitionAssignor());
-    builder.members(
-        description.members().stream()
-            .map(m ->
-                InternalConsumerGroup.InternalMember.builder()
-                  .assignment(m.assignment().topicPartitions())
-                  .clientId(m.clientId())
-                  .groupInstanceId(m.groupInstanceId().orElse(""))
-                  .consumerId(m.consumerId())
-                  .clientId(m.clientId())
-                  .host(m.host())
-                  .build()
-            ).collect(Collectors.toList())
-    );
-    builder.offsets(offsets);
-    Optional.ofNullable(description.coordinator()).ifPresent(builder::coordinator);
-    return builder.build();
-  }
-
-  public static ConsumerGroupDTO convertToConsumerGroup(InternalConsumerGroup c) {
-    return convertToConsumerGroup(c, new ConsumerGroupDTO());
-  }
-
-  public static <T extends ConsumerGroupDTO> T convertToConsumerGroup(
-      InternalConsumerGroup c, T consumerGroup) {
-    consumerGroup.setGroupId(c.getGroupId());
-    consumerGroup.setMembers(c.getMembers().size());
-
-    int numTopics = Stream.concat(
-        c.getOffsets().keySet().stream().map(TopicPartition::topic),
-        c.getMembers().stream()
-            .flatMap(m -> m.getAssignment().stream().map(TopicPartition::topic))
-    ).collect(Collectors.toSet()).size();
-
-    long messagesBehind = c.getOffsets().entrySet().stream()
-        .mapToLong(e ->
-            Optional.ofNullable(c.getEndOffsets())
-              .map(o -> o.get(e.getKey()))
-              .map(o -> o - e.getValue().offset())
-              .orElse(0L)
-        ).sum();
-
-    consumerGroup.setMessagesBehind(messagesBehind);
-    consumerGroup.setTopics(numTopics);
-    consumerGroup.setSimple(c.isSimple());
-
-    Optional.ofNullable(c.getState())
-        .ifPresent(s -> consumerGroup.setState(mapConsumerGroupState(s)));
-    Optional.ofNullable(c.getCoordinator())
-        .ifPresent(cd -> consumerGroup.setCoordinator(mapCoordinator(cd)));
-
-    consumerGroup.setPartitionAssignor(c.getPartitionAssignor());
-    return consumerGroup;
-  }
-
-  public static ConsumerGroupDetailsDTO convertToConsumerGroupDetails(InternalConsumerGroup g) {
-    ConsumerGroupDetailsDTO details = convertToConsumerGroup(g, new ConsumerGroupDetailsDTO());
-    Map<TopicPartition, ConsumerGroupTopicPartitionDTO> partitionMap = new HashMap<>();
-
-    for (Map.Entry<TopicPartition, OffsetAndMetadata> entry : g.getOffsets().entrySet()) {
-      ConsumerGroupTopicPartitionDTO partition = new ConsumerGroupTopicPartitionDTO();
-      partition.setTopic(entry.getKey().topic());
-      partition.setPartition(entry.getKey().partition());
-      partition.setCurrentOffset(entry.getValue().offset());
-
-      final Optional<Long> endOffset = Optional.ofNullable(g.getEndOffsets())
-          .map(o -> o.get(entry.getKey()));
-
-      final Long behind = endOffset.map(o -> o - entry.getValue().offset())
-          .orElse(0L);
-
-      partition.setEndOffset(endOffset.orElse(0L));
-      partition.setMessagesBehind(behind);
-
-      partitionMap.put(entry.getKey(), partition);
-    }
-
-    for (InternalConsumerGroup.InternalMember member : g.getMembers()) {
-      for (TopicPartition topicPartition : member.getAssignment()) {
-        final ConsumerGroupTopicPartitionDTO partition = partitionMap.computeIfAbsent(
-            topicPartition,
-            (tp) -> new ConsumerGroupTopicPartitionDTO()
-                .topic(tp.topic())
-                .partition(tp.partition())
-        );
-        partition.setHost(member.getHost());
-        partition.setConsumerId(member.getConsumerId());
-        partitionMap.put(topicPartition, partition);
-      }
-    }
-    details.setPartitions(new ArrayList<>(partitionMap.values()));
-    return details;
-  }
-
-  private static BrokerDTO mapCoordinator(Node node) {
-    return new BrokerDTO().host(node.host()).id(node.id());
-  }
-
-  private static ConsumerGroupStateDTO mapConsumerGroupState(
-      org.apache.kafka.common.ConsumerGroupState state) {
-    switch (state) {
-      case DEAD: return ConsumerGroupStateDTO.DEAD;
-      case EMPTY: return ConsumerGroupStateDTO.EMPTY;
-      case STABLE: return ConsumerGroupStateDTO.STABLE;
-      case PREPARING_REBALANCE: return ConsumerGroupStateDTO.PREPARING_REBALANCE;
-      case COMPLETING_REBALANCE: return ConsumerGroupStateDTO.COMPLETING_REBALANCE;
-      default: return ConsumerGroupStateDTO.UNKNOWN;
-    }
-  }
-
   public static int convertToIntServerStatus(ServerStatusDTO serverStatus) {
     return serverStatus.equals(ServerStatusDTO.ONLINE) ? 1 : 0;
   }
@@ -211,41 +78,4 @@ public class ClusterUtil {
         throw new IllegalArgumentException("Unknown timestampType: " + timestampType);
     }
   }
-
-  public static Optional<InternalConsumerGroup> filterConsumerGroupTopic(
-      InternalConsumerGroup consumerGroup, Optional<String> topic) {
-
-    final Map<TopicPartition, OffsetAndMetadata> offsets =
-        consumerGroup.getOffsets().entrySet().stream()
-            .filter(e -> topic.isEmpty() || e.getKey().topic().equals(topic.get()))
-            .collect(Collectors.toMap(
-                Map.Entry::getKey,
-                Map.Entry::getValue
-            ));
-
-    final Collection<InternalConsumerGroup.InternalMember> members =
-        consumerGroup.getMembers().stream()
-            .map(m -> filterConsumerMemberTopic(m, topic))
-            .filter(m -> !m.getAssignment().isEmpty())
-            .collect(Collectors.toList());
-
-    if (!members.isEmpty() || !offsets.isEmpty()) {
-      return Optional.of(
-          consumerGroup.toBuilder()
-            .offsets(offsets)
-            .members(members)
-            .build()
-      );
-    } else {
-      return Optional.empty();
-    }
-  }
-
-  public static InternalConsumerGroup.InternalMember filterConsumerMemberTopic(
-      InternalConsumerGroup.InternalMember member, Optional<String> topic) {
-    final Set<TopicPartition> topicPartitions = member.getAssignment()
-        .stream().filter(tp -> topic.isEmpty() || tp.topic().equals(topic.get()))
-        .collect(Collectors.toSet());
-    return member.toBuilder().assignment(topicPartitions).build();
-  }
 }

kafka-ui-api/src/test/java/com/provectus/kafka/ui/KafkaConsumerGroupTests.java

@@ -1,9 +1,17 @@
 package com.provectus.kafka.ui;
 
+import static org.assertj.core.api.Assertions.assertThat;
+
+import com.provectus.kafka.ui.model.ConsumerGroupDTO;
+import com.provectus.kafka.ui.model.ConsumerGroupsPageResponseDTO;
+import java.io.Closeable;
 import java.time.Duration;
+import java.util.Comparator;
 import java.util.List;
 import java.util.Properties;
 import java.util.UUID;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
 import lombok.extern.slf4j.Slf4j;
 import lombok.val;
 import org.apache.kafka.clients.admin.NewTopic;
@@ -78,8 +86,59 @@ public class KafkaConsumerGroupTests extends AbstractBaseTest {
         .isBadRequest();
   }
 
+
+  @Test
+  void shouldReturnConsumerGroupsWithPagination() throws Exception {
+    try (var groups1 = startConsumerGroups(3, "cgPageTest1");
+        var groups2 = startConsumerGroups(2, "cgPageTest2")) {
+      webTestClient
+          .get()
+          .uri("/api/clusters/{clusterName}/consumer-groups/paged?perPage=3&search=cgPageTest", LOCAL)
+          .exchange()
+          .expectStatus()
+          .isOk()
+          .expectBody(ConsumerGroupsPageResponseDTO.class)
+          .value(page -> {
+            assertThat(page.getPageCount()).isEqualTo(2);
+            assertThat(page.getConsumerGroups().size()).isEqualTo(3);
+          });
+
+      webTestClient
+          .get()
+          .uri("/api/clusters/{clusterName}/consumer-groups/paged?perPage=10&search=cgPageTest", LOCAL)
+          .exchange()
+          .expectStatus()
+          .isOk()
+          .expectBody(ConsumerGroupsPageResponseDTO.class)
+          .value(page -> {
+            assertThat(page.getPageCount()).isEqualTo(1);
+            assertThat(page.getConsumerGroups().size()).isEqualTo(5);
+            assertThat(page.getConsumerGroups())
+                .isSortedAccordingTo(Comparator.comparing(ConsumerGroupDTO::getGroupId));
+          });
+    }
+  }
+
+  private Closeable startConsumerGroups(int count, String consumerGroupPrefix) {
+    String topicName = createTopicWithRandomName();
+    var consumers =
+        Stream.generate(() -> {
+          String groupId = consumerGroupPrefix + UUID.randomUUID();
+          val consumer = createTestConsumerWithGroupId(groupId);
+          consumer.subscribe(List.of(topicName));
+          consumer.poll(Duration.ofMillis(100));
+          return consumer;
+        })
+        .limit(count)
+        .collect(Collectors.toList());
+    return () -> {
+      consumers.forEach(KafkaConsumer::close);
+      deleteTopic(topicName);
+    };
+  }
+
   private String createTopicWithRandomName() {
-    String topicName = UUID.randomUUID().toString();
+    String topicName = getClass().getSimpleName() + "-" + UUID.randomUUID();
     short replicationFactor = 1;
     int partitions = 1;
     createTopic(new NewTopic(topicName, partitions, replicationFactor));

kafka-ui-contract/src/main/resources/swagger/kafka-ui-api.yaml

@@ -615,6 +615,46 @@ paths:
                 items:
                   $ref: '#/components/schemas/ConsumerGroup'
 
+  /api/clusters/{clusterName}/consumer-groups/paged:
+    get:
+      tags:
+        - Consumer Groups
+      summary: Get consumer croups with paging support
+      operationId: getConsumerGroupsPage
+      parameters:
+        - name: clusterName
+          in: path
+          required: true
+          schema:
+            type: string
+        - name: page
+          in: query
+          required: false
+          schema:
+            type: integer
+        - name: perPage
+          in: query
+          required: false
+          schema:
+            type: integer
+        - name: search
+          in: query
+          required: false
+          schema:
+            type: string
+        - name: orderBy
+          in: query
+          required: false
+          schema:
+            $ref: '#/components/schemas/ConsumerGroupOrdering'
+      responses:
+        200:
+          description: OK
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ConsumerGroupsPageResponse'
+
 
   /api/clusters/{clusterName}/consumer-groups/{id}:
     get:
@@ -1863,6 +1903,23 @@ components:
       required:
         - groupId
 
+    ConsumerGroupOrdering:
+      type: string
+      enum:
+        - NAME
+        - MEMBERS
+        - STATE
+
+    ConsumerGroupsPageResponse:
+      type: object
+      properties:
+        pageCount:
+          type: integer
+        consumerGroups:
+          type: array
+          items:
+            $ref: '#/components/schemas/ConsumerGroup'
+
     CreateTopicMessage:
       type: object
       properties: