Kafka List Consumer Groups

bin/kafka-consumer-groups. A Consumer Group's Relationship to Partitions. 3) without using Receivers. KafkaConsumer(). In this session, we will look at the code for our fist Kafka consumer and try to understand some details around it. You can read more about the acl structure on KIP-11. Supports parsing the Apache Kafka 0. First thing to know is that the High Level Consumer stores the last offset read from a specific partition in ZooKeeper. apache-kafka. This would be helpful so that the system tools can be explored more easily. So if there is a topic with four partitions, and a consumer group with two processes, each. List of Topics. The brokers list the consumer group (named "default"), but I can't query the offsets:. Flink's Kafka consumer is called FlinkKafkaConsumer08 (or 09 for Kafka 0. Another interesting admin tool is the kafka-consumer-groups. 0, the main change introduced is for previous versions consumer groups were managed by Zookeeper, but for 9+ versions they are managed by Kafka broker. Internally, MirrorMaker2 uses the Kafka Connect framework which in turn use the Kafka high level consumer to read data from Kafka. 最近工作中遇到需要使用kafka的场景,测试消费程序启动后,要莫名的过几十秒乃至几分钟才能成功获取到到topic的partition和offset,而后开始消费数据,于是学习了一下查看kafka broker里topic和consumer group状态的相关命令,这里记录一下。. Kafka retains messages for a configurable period of time and it is up to the consumers to adjust their behaviour accordingly. ” A Kafka server by default starts at port 9092. 这个group是以下两种情况之一:刚创建没有读取数据;或者读取数据后没有向zookeeper报告已读到哪一条。 这样的group就可以用来在开发环境做调试,在调试代码中加上对consumer参数的配置auto. A consumer group may have one or more consumers. Consumers are in reality consumer groups, that run one or more consumer processes. When the consumer subscribes to a topic and it gets the partitions assignments. Have a look at this article for more information about consumer groups. I don't know what to put there. AUTO_OFFSET_RESET_CONFIG specifies what to do when there is no initial offset in Kafka or if the current offset does not exist any more on the server (e. Then you need to designate a Kafka record key deserializer and a record value deserializer. Bootstrap_Servers config as specified in the Kafka official site is “A list of host/port pairs to use for establishing the initial connection to the Kafka cluster. Ashish Singh Hello Kiran, kafka-consumer-groups. When Kafka was originally created, it shipped with a Scala producer and consumer client. In our previous session, we covered Kafka consumer groups. The Kafka consumer uses the poll method to get N number of records. Producers and Consumers are clients of Kafka brokers. Consume records from a Kafka cluster. because that data has been deleted):. sh will be released as part of 0. To find the consumer group name, look inside the mirrormaker-consumer. properties file for the group. Kafka Consumer. 目前kafka集群启用SASL_PLAINTEXT权限和ACl,在使用kafka-consumer-group. 0 Add nodes consumer group and offset. List the certificate (keystore) being used by the consumer. a topic, then all operations on that resource will be denied to any principal (AKA certificate) not explicitly listed for that resource. bin/kafka-run-class. This tool allows us to list, describe, and delete consumer groups. Group_Id is the id of the group to which our consumer belongs. Spring Kafka Consumer Producer Example 10 minute read In this post, you're going to learn how to create a Spring Kafka Hello World example that uses Spring Boot and Maven. So, this was all about Apache Kafka Consumer and Consumer group in Kafka with examples. Note that deletion is only available when the group metadata is stored in ZooKeeper. Command Line interface. group_id='counters': this is the consumer group to which the consumer belongs. 0 was about introducing a brand new Consumer API aka New Consumer. 4 for the Python API. 0, the id property (if present) is used as the Kafka consumer group. It helps you move your data where you need it, in real time, reducing the headaches that come with integrations between multiple source and target systems. It has Producer, Consumer, Streams and Connector APIs. Kafka enables both the above models through "Consumer group" concept making it scalable in processing and a multi-subscriber. Articles posted here do not necessarily represent the views or the position of the Farm-to-Consumer Legal Defense. sh in the Kafka directory are the tools that help to create a Kafka Producer and Kafka Consumer respectively. In order to use WildFly OpenSSL, I went ahead and cloned the github repo. A string that uniquely identifies the group of consumer processes to which this consumer belongs. Many companies use Kafka as a "circulatory system" for their applications. Multiple Kafka consumer groups can be run in parallel: Of course you can run multiple, independent logical consumer applications against the same Kafka topic. The consumers in a group then divides the topic partitions as fairly amongst themselves as possible by establishing that each partition is only consumed by. If it does, then you should adjust the timeouts in kafka configs. Consume records from a Kafka cluster. What to do when there is no initial offset in Kafka or if an offset is out of range: smallest: automatically reset the offset to the smallest offset largest: automatically reset the offset to the largest offset disable: throw exception to the consumer if no previous offset is found for the consumer's group. Get a list of consumer groups. Kafka consumer group info retrieval using Python. group-id property needs to be specified as we are using group management to assign topic partitions to consumers. I don't know what to put there. Ashish Singh Hello Kiran, kafka-consumer-groups. In the second half of the tutorial you'll learn how to partition and group messages, and how to control which messages a Kafka consumer will consume. Each partition is assigned to a single consumer process so that the same message is not read twice. The consumer is single threaded and multiplexes I/O over TCP connections to each of the brokers it needs to. Hi, I am using kafka version 0. Using the kafka-console-consumer to consume records from a topic. The Logstash Kafka consumer handles group management and uses the default offset management strategy using Kafka topics. Hope you like our explanation. When I am trying to get the list of consumer groups and describe group with. Kafka-Consumer-Groups is a CLI tool which can be used to get the message consumption from Kafka. Let's get started. If we run a Kafka console producer or consumer, that are not ACL configured, like this. It has Producer, Consumer, Streams and Connector APIs. In this post we have learned how to create a simple Producer and Consumer for a Kafka topic using Java Client API. group property to specify a group name. Hello and welcome to Kafka tutorials at Learning Journal. (Step-by-step) So if you're a Spring Kafka beginner, you'll love this guide. Consumer groups. 0 and later for both reading from and writing to Kafka topics. The Kafka brokers are an important part of the puzzle, but do not provide the Consumer Group behavior directly. 0 Add nodes consumer group and offset. The consumers specify what topics they want to listen to. Base class to be used by other consumers. So, you can check the lag using the kafka-consumer-groups. The project aims to provide a unified, high-throughput, low-latency platform for handling real-time data feeds. The brokers list the consumer group (named "default"), but I can't query the offsets:. The Logstash Kafka consumer handles group management and uses the default offset management strategy using Kafka topics. 0, the main change introduced is for previous versions consumer groups were managed by Zookeeper, but for 9+ versions they are managed by Kafka broker. If all the consumer instances have the same consumer group, then this works just like a traditional queue balancing load over the consumers. Path to Purchase IQ delivers leading service and solution providers the most targeted opportunities to emphasize their commitment to the consumer goods industry. bin/kafka-consumer-groups. In the Bootstrap servers property, specify the host name and port of the Kafka server; for example, if you are using IBM Event Streams (Kafka on IBM Cloud), specify the address of that server. Remember from the introduction that a consumer needs to be part of a consumer group to make the auto commit work. Consumers in the same group divide up and share partitions as we demonstrated by running three consumers in the same group and one producer. Or one might want some assignment that results in uniform workloads, based on the number of messages in each partition. GitHub Gist: instantly share code, notes, and snippets. You can see the current consumer groups, for each group the topics that they are consuming and the position of the group in each topic queue. And maybe most important parameter here - group. I am Interested to know if Informatica cloud provides it as an Add. */ zookeeperConnect: String,. We can start another consumer with the same group id and they will read messages from different partitions of the topic in parallel. Consumer(client, group, topic, partitions=None, auto_commit=True, auto_commit_every_n=100, auto_commit_every_t=5000)¶ Bases: object. For a given cluster, this tool provides us with the following functionalities: Manipulating consumer-groups: Listing consumer-groups subscribed to the cluster. The Consumer API from Kafka helps to connect to Kafka cluster and consume the data streams. It manages the messages received and send them to the consumer; Cluster: a group of machines, each executing one instance of Kafka. When Kafka was originally created, it shipped with a Scala producer and consumer client. Kafka consumer properties; they will supersede any properties with the same name defined in the consumer factory (if the consumer factory supports property overrides). Group struct { Session struct { // The timeout used to detect consumer failures when using Kafka's group management facility. sh --bootstrap-server localhost:9092 --list. Hello and welcome to Kafka tutorials at Learning Journal. KAFKA Simple Consumer Reading Description This function returns one message at a time which are read by a KAFKA Simple Consumer Usage rkafka. 0 was about introducing a brand new Consumer API aka New Consumer. Kafka consumer group info retrieval using Python. 1 include: [KAFKA-2761] - Enable passing regex via whitelist for new-consumer in ConsoleConsumer. bob consumes from topic test in consumer-group bob-group. They are extracted from open source Python projects. kafka-consumer-groups --bootstrap-server broker: 9092--describe--group console-consumer-36650 Note: This will only show information about consumers that use the Java consumer API (non-ZooKeeper-based consumers). In this post we have learned how to create a simple Producer and Consumer for a Kafka topic using Java Client API. Which message does the consumer group start reading from in the Kafka Topic? How long does the step run for before exiting? We’ll get to those answers in a few minutes. Sending Records With Kafka Producer. Back in January 2019, I presented an introduction to Kafka basics and spring-kafka at a South Bay JVM User Group meetup. 目前kafka集群启用SASL_PLAINTEXT权限和ACl,在使用kafka-consumer-group. 9 Java Client API Example. Consumer groups give Kafka the flexibility to have the advantages of both message queuing and publish-subscribe models. The Confluent. Connector API – Executes the reusable producer and consumer APIs that can link the topics to the existing applications. Requires that consumer_group is not None. Use Kafka with C# Menu. In this example we'll be using Confluent's kafka-dotnet client. I don't know what to put there. Apache Kafka Generic Avro Producer/Consumer. Setting Up a Test Kafka Broker on Windows. Example: Produce a message to the Kafka cluster. Starting with version 2. NET framework. The list will show both the start/end offsets of the partitions as well as the offset of consumers within each partition. In other words, within each subscribing consumer group, each record published to a topic is delivered to one consumer instance. You created a Kafka Consumer that uses the topic to receive messages. This PluralSight intro. Getting started with apache-kafka; Consumer Groups and Offset Management; Custom Serializer/Deserializer; kafka console tools; kafka-console-consumer; kafka-console-producer; kafka-consumer-groups; kafka-simple-consumer-shell; kafka-topics; Producer/Consumer in Java. Is there a tool I can run to get a list of consumer groups?. If you use kafka-console-consumer. Apache Kafka: Low Level api Consumer If you want greater control over partition consumption then High Level api consumer you may implement it in low level api. When Kafka was originally created, it shipped with a Scala producer and consumer client. Duration // WatchForPartitionChanges is used to inform kafka-go that a consumer group should be // polling the brokers and rebalancing if any partition changes happen to the topic. The easiest way to integrate the info in kafka_consumer. The consumer is the receiver of the message in Kafka. Pulsar provides an easy option for applications that are currently written using the Apache Kafka Java client API. Apache Kafka has a feature named consumer groups that helps distribute message consumption loads across sets of consumers. If you use kafka-console-consumer. Reading margins are tracked for each group separately. Provides Kafka FETCH and OFFSETS requests. Producers and Consumers are clients of Kafka brokers. Before we start creating different types of Kafka Consumers, it is necessary to understand some nuances of a Kafka Consumer group. First thing to know is that the High Level Consumer stores the last offset read from a specific partition in ZooKeeper. We can check the Consumer console simultaneously as well, to check the tweets collected in real-time using, the below command:. I use MacOS for development and will be using this for my tests. As with the publish-subscribe, it allows you to broadcast messages to multiple consumer groups. id that identifies which consumer group this consumer belongs. Apache Kafka Specific Avro Producer/Consumer + Kafka Schema Registry Posted on 27/06/2018 by sachabarber in Distributed Systems , kaf , Kafka This is the 2nd post in a small mini series that I will be doing using Apache Kafka + Avro. Further, the output of the Second Process. Additionally, we'll use this API to implement transactional. 9 Java Client API Example. id property, overriding the configured property in the consumer factory, if present. When Kafka was originally created, it shipped with a Scala producer and consumer client. ACL had location as Austin, while cert had location as Atlanta. If two consumers subscribe from different groups, each will receive a copy of every event. a topic, then all operations on that resource will be denied to any principal (AKA certificate) not explicitly listed for that resource. There are no Apache Kafka Cluster specific configuration metrics supported. The constructor accepts the following arguments: The topic name / list of topic names; A DeserializationSchema / KeyedDeserializationSchema for deserializing the data from Kafka. With the console producer and consumers running, I'd like to run the ConsumerOffsetChecker, but it requires a group parameter. In our previous session, we covered Kafka consumer groups. The Kafka brokers are an important part of the puzzle, but do not provide the Consumer Group behavior directly. It also interacts with the assigned kafka Group Coordinator node to allow multiple consumers to load balance consumption of topics (requires kafka >= 0. In some scenarios (for example, Kafka group-based authorization), you may want to use specific authorized group IDs to read data. The new consumer was introduced in version 0. Hope you like our explanation. In the Consumer group ID property, specify the ID of the consumer group to which this consumer belongs. 9+ Wire Format protocol. If you use kafka-console-consumer. Kafka will deliver each message in the subscribed topics to one process in each consumer group. I know the java cli tools has this command: bin/kafka-consumer-groups. Apache Kafka - Consumer Group Example - Consumer group is a multi-threaded or multi-machine consumption from Kafka topics. In this tutorial, you learn how to:. If a consumer group is inactive during this period, and starts after the expiration, the coordinator won't find any offsets and Kafka will rely on the consumer auto. List of Topics. num_consumer_fetchers (int) - The number of workers used to make FetchRequests; auto_commit_enable (bool) - If true, periodically commit to kafka the offset of messages already returned from consume() calls. Consumers label themselves with a consumer group name. The other point is that I am mainly a Windows user, as such the instructions, scripts will have a Windows bias to them. Consumer group 'bob-group' has no active members. Multithreaded Processing. Part 2 is about collecting operational data from Kafka, and Part 3 details how to monitor Kafka with Datadog. This article explains how to write Kafka Producer and Consumer example in Scala. Consumers in Kafka are organized into consumer groups. We have a tool that will show the position of all consumers in a consumer group as well as how far behind the end of the log they are. With the console producer and consumers running, I'd like to run the ConsumerOffsetChecker, but it requires a group parameter. We have established consumer connection, now we can get streams, and consume them. It does this by consuming the special internal Kafka topic to which consumer offsets are written. since our topic was created with 4 partitions, we. 0, the id property (if present) is used as the Kafka consumer group. charlie queries the group bob-group to retrieve the group offsets. In our previous session, we covered Kafka consumer groups. auto-offset-reset property needs to be set to 'earliest' which ensures the new consumer group will get the message sent in case the container started after the send was completed. Consumers label themselves with a consumer group name, and each message published to a topic is delivered to one consumer instance within each subscribing consumer group. Following is a picture demonstrating the working of Consumer in Apache Kafka. Consumers in Kafka are organized into consumer groups. Overview: This is a 3rd part in the Kafka series. The other point is that I am mainly a Windows user, as such the instructions, scripts will have a Windows bias to them. The consumers specify what topics they want to listen to. You may start using the Kafka endpoint from your applications with no code change but a minimal configuration change. If any consumer or broker fails to send heartbeat to ZooKeeper, then it can be re-configured via the Kafka cluster. Base class to be used by other consumers. Works with 64-bit elements of the Kafka Wire Format protocol on 32 bit systems. The Event Hubs for Kafka feature provides a protocol head on top of Azure Event Hubs that is binary compatible with Kafka versions 1. subscribe(Collections. properties Note: This will not show information about old Zookeeper-based consumers. kafka中topic和consumer group 是怎么关联的? 怎么通过topic名查找到订阅了该topic的consumer group?怎么找到consumer group订阅的所有topic? 拜托各位大神,找了好久资料了,还是没弄清 显示全部. sh --list --bootstrap-server localhost:9092. This is achieved by balancing the partitions between all members in the consumer group so that each partition is assigned to exactly one consumer in the group. Apache Kafka is a distributed streaming messaging platform. List the certificate (keystore) being used by the consumer. Currently, there are no available JMX metrics for consumer lag from the Kafka broker itself. Learn about the consumer group experience, how things can be broken, and what offset commits are so that you don't use Apache Kafka consumer groups incorrectly. bin/kafka-console-producer. initialization and fetching metadata of partitions. We also need to provide a group ID: this is to identify the consumer group that our consumer will join. If we run a Kafka console producer or consumer, that are not ACL configured, like this. sh and bin/kafka-console-consumer. Kafka component added to the project (you can just add it via Nuget). This PluralSight intro. I don't know what to put there. If the list of partitions for a topic is empty (ex: "consumer_group": {"topic": []}), then offsets for all partitions of that topic will be collected for the consumer group. Historically, consumer advocates have assumed a somewhat adversarial role in exposing unfair business practices or unsafe products that threaten the welfare of the general public. kafka_topic_list – A list of Kafka topics. They behave differently when they stop working, depending on the producer and consumer configuration. So, this was all about Apache Kafka Consumer and Consumer group in Kafka with examples. kafka-avro-console-consumer --topic position-reports --new-consumer --bootstrap-server localhost:9092 --from-beginning --property schema. Kafka Offset Monitor. TopicPartition(). Kafka has four core APIs: Producers : Producer applications sending message records to the kafka cluster. kafka-python is best used with newer brokers (0. bin/kafka-consumer-groups. In some scenarios (for example, Kafka group-based authorization), you may want to use specific authorized group IDs to read data. x versions). The underlying implementation is using the KafkaConsumer, see Kafka API for a description of consumer groups, offsets, and other details. readFromSimpleConsumer(SimpleConsumerObj) Arguments SimpleConsumerObj Consumer through which messages were received Required:Mandatory Type:Consumer Details There are two types of KAFKA consumers:High. For example, we had a "high-level" consumer API which supported consumer groups and handled failover, but didn't support many of the more. sh shell script. This consumer creates an infinite loop, and each time through will use consumer. Setting up Kafka infrastructure We'll set up the Kafka infrastructure locally using the Docker Compose Template that I describe in my Kafka: A Basic Tutorial blog post. List consumer groups: kafka-consumer-groups --bootstrap-server localhost:9092 --list octopus Describe a consumer. (Step-by-step) So if you're a Spring Kafka beginner, you'll love this guide. In the Consumer group ID property, specify the ID of the consumer group to which this consumer belongs. Kafka ACLs are used to restrict access to Kafka cluster operations, Kafka topics, and Kafka consumer groups. Hello-Kafka Since we have created a topic, it will list out Hello-Kafka only. The Consumer API from Kafka helps to connect to Kafka cluster and consume the data streams. Copying, deleting and renaming of the group. Command Line interface. group-id property needs to be specified as we are using group management to assign topic partitions to consumers. After a bit of head-scratching I realised that my local Kafka environment had been rebuilt (I use Docker Compose so complete rebuilds to start from scratch are easy), hence no data in the topic. Requires that consumer_group is not None. GitHub Gist: instantly share code, notes, and snippets. …It's called Kafka consumer groups. I don't know what to put there. Supports parsing the Apache Kafka 0. That means having more consumers than the number of partitions of the topic is not very useful as extra consumers will. Another interesting admin tool is the kafka-consumer-groups. The programming language will be Scala. public class KafkaConsumer extends java. Subscribed to topic Hello-kafka offset = 3, key = null, value = Test consumer group 02. The most important way is by automatically monitoring all consumers, and doing so for every partition that they consume. It manages the messages received and send them to the consumer; Cluster: a group of machines, each executing one instance of Kafka. The consumer is not thread safe and should not be shared across threads. A message is sent to all the consumers in a consumer group. The project aims to provide a unified, high-throughput, low-latency platform for handling real-time data feeds. Kafka Consumer Groups List the consumer groups known to Kafka. GROUP_ID_CONFIG specifies a unique string that identifies the consumer group this consumer belongs to. Which message does the consumer group start reading from in the Kafka Topic? How long does the step run for before exiting? We’ll get to those answers in a few minutes. The #pause() and #resume() provides global control over reading the records from the consumer. bin/kafka-console-consumer. In this session, we will look at the code for our fist Kafka consumer and try to understand some details around it. You created a Kafka Consumer that uses the topic to receive messages. group_id=’counters’: this is the consumer group to which the consumer belongs. org Each Kafka consumer is able to configure a consumer group that it belongs to, and can dynamically set the list of topics it wants to subscribe to through one of the subscribe APIs. The underlying implementation is using the KafkaConsumer, see Kafka API for a description of consumer groups, offsets, and other details. Consumer Groups -They are used to read and process data in parallel. id value is specified by the Kafka consumer client and is used to distinguish between different clients. It also interacts with the assigned kafka Group Coordinator node to allow multiple consumers to load balance consumption of topics (requires kafka >= 0. If a consumer group is inactive during this period, and starts after the expiration, the coordinator won’t find any offsets and Kafka will rely on the consumer auto. For example, fully coordinated consumer groups -- i. This Kafka tutorial demonstrates how Kafka consumer failover and Kafka broker failover. When I am trying to get the list of consumer groups and describe group with. KAFKA Simple Consumer Reading Description This function returns one message at a time which are read by a KAFKA Simple Consumer Usage rkafka. Consumer groups give Kafka the flexibility to have the advantages of both message queuing and publish-subscribe models. Setting Up a Test Kafka Broker on Windows. Kafka Consumer; Kafka Consumer Groups; Kafka Producer; Kafka Connect What is Kafka Connect? Kafka Connect is a framework for Kafka used to interact with external systems such as files, databases, Hadoop clusters, and equivalent cloud-based versions. Then you need to designate a Kafka record key deserializer and a record value deserializer. sh --new-consumer --bootstrap-server localhost:9092 --describe --group test-consumer-group Managing Consumer Groups 管理消费者组 With the ConsumerGroupCommand tool, we can list, describe, or delete consumer groups. It manages the messages received and send them to the consumer; Cluster: a group of machines, each executing one instance of Kafka. If all the consumer instances have different consumer groups, then this works like publish-subscribe and all messages are broadcast to all consumers. Kafka consumer properties; they will supersede any properties with the same name defined in the consumer factory (if the consumer factory supports property overrides). sh --list --zookeeper localhost:2181 Output. ConsumerConnector: This is used for establishing a connection with the Zookeeper. In Kafka, no partition will be read by two consumers from the same group. KAFKA Simple Consumer Reading Description This function returns one message at a time which are read by a KAFKA Simple Consumer Usage rkafka. bob consumes from topic test in consumer-group bob-group. Is there a tool I can run to get a list of consumer groups?. After the load test when our consumers and have two times now seen Kafka become stuck in consumer group rebalancing. …It's called Kafka consumer groups. • Expert power-groups possess knowledge that members, prospective members, or other consumers seek (doctor) • Reward power- groups have the power to reward members for various behaviors (parent) • Coercive power-groups have the power to sanction group members for breaking the rules or failing to follow expectations (coach). The article shows how, with many groups, Kafka acts like a Publish/Subscribe MOM. id is a must have property and here it is an arbitrary value. kafka-avro-console-consumer --topic position-reports --new-consumer --bootstrap-server localhost:9092 --from-beginning --property schema. This is a mailing list for kafka client developers to share tips, tricks, problems, and so on, related to writing client libraries to interact with the apache kafka server. That means having more consumers than the number of partitions of the topic is not very useful as extra consumers will. We had the issue that consumer groups are re-balancing and we didn't knew if it's related to application logic or the Consumer Group Coordinator was changing and the Kafka cluster was reassign a different one each time. Example results of running this (with consumer group 'signatures' and topic 'ingest') are: Group Topic Pid Offset logSize Lag Owner. Kafka acls are defined in the general format of "Principal P is [Allowed/Denied] Operation O From Host H On Resource R". This base class provides logic for. Consumer API – Permits the application to subscribe to the topics and processes the stream of records. Quick command reference for Apache Kafka. Note that you would not get the [IKI_CODE] metric from consumers using a consumer library other than the Java one. In the Consumer group ID property, specify the ID of the consumer group to which this consumer belongs. The Kafka consumer uses the poll method to get N number of records. So, you can check the lag using the kafka-consumer-groups. Starting with version 2. If it does, then you should adjust the timeouts in kafka configs. This release of Kafka Connect is associated with MEP 2. The Kafka brokers are an important part of the puzzle, but do not provide the Consumer Group behavior directly. Consume records from a Kafka cluster. Further fixes to make connection more robust on kafka up/down Multi host per broker Multi Topic for consumer. If that should be reset, for ex based on a duration. When a consumer is created, it requires bootstrap. Listing all consumer groups for a cluster is always returning empty list Here is the code used to create a consumer-group to load data from a kafka topic. If any consumer or broker fails to send heartbeat to ZooKeeper, then it can be re-configured via the Kafka cluster. A Consumer Group based application may run on several nodes, and when they start up. Currently, there are no available JMX metrics for consumer lag from the Kafka broker itself. …It's called Kafka consumer groups.