Because the Kafka and ZooKeeper configurations are separate, it is easy to make mistakes. For example, administrators may set up SASL on Kafka, and incorrectly think that they have secured all of the data travelling over the network. In fact, it is also necessary to configure security in the separate, external ZooKeeper system in order to do this. Unifying the two systems would give a uniform security configuration model. Previously, under certain rare conditions, if a broker became partitioned from Zookeeper but . Supporting multiple metadata storage options would inevitably decrease the amount of testing we could give to each configuration. Our system tests would have to either run with every possible configuration storage mechanism, which would greatly increase the resources needed, or choose to leave some user under-tested. Increasing the size of test matrix in this fashion would really hurt the project. Below is the Kafka cluster setup. References: KIP-500: Replace ZooKeeper … This KIP presents an overall vision for a scalable post-ZooKeeper Kafka. This post was jointly written by Neha Narkhede, co-creator of Apache Kafka, and Flavio Junqueira, co-creator of Apache ZooKeeper.. Just like ZooKeeper, Raft requires a majority of nodes to be running in order to continue running. Therefore, a three-node controller cluster can survive one failure. A five-node controller cluster can survive two failures, and so on. Colin McCabe and Jason Gustafson discuss the history of Kafka, the creation of KIP-500, and the implications of removing ZooKeeper dependency and replacing … KIP-558 is enabled by default. Proposed Changes Deployment KIP-500 Mode Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast). ( Log Out / In the future, I want to see the elimination of the second Kafka cluster for controllers and eventually, we should be able to manage the metadata within the actual Kafka cluster. In the KIP's Motivation and Overview you mentioned the LeaderAndIsr and UpdateMetadata RPC. Eventually, the active controller will ask the broker to finally go offline, by returning a special result code in the MetadataFetchResponse. Alternately, the broker will shut down if the leaders can't be moved in a predetermined amount of time. For the latest version (2.4.1) ZooKeeper is still required for running Kafka, but in the near future, ZooKeeper dependency will be removed from Apache Kafka. Hereby essay describes the process of replacing ZooKeeper with Atomix, a … It is no longer necessary to use ZooKeeper for making these changes, hence this improvement also plays part in a bigger effort to remove ZooKeeper… We will create follow-on KIPs to hash out the concrete details of each change. Electing another Kafka broker as a controller requires pulling the metadata from the Zookeeper which leads to the Kafka cluster unavailability. When the broker is in the Fenced state, it will not respond to RPCs from clients. The broker will be in the fenced state when starting up and attempting to fetch the newest metadata. It will re-enter the fenced state if it can't contact the active controller. Fenced brokers should be omitted from the metadata sent to clients. ( Log Out / When Kafka Controller fails, a new one needs to load a full cluster state from ZooKeeper, which can take a while. The brokers in the Kafka cluster will periodically pull the metadata from the controller. Finally, in the future we may want to support a single-node Kafka mode. This would be useful for people who wanted to quickly test out Kafka without starting multiple daemons. Removing the ZooKeeper dependency makes this possible. Currently, Apache Kafka is using Zookeeper to manage its cluster metadata. Every partition leader maintains the ISR list or the list of ISRs. Note that although the controller processes are logically separate from the broker processes, they need not be physically separate. In some cases, it may make sense to deploy some or all of the controller processes on the same node as the broker processes. This is similar to how ZooKeeper processes may be deployed on the same nodes as Kafka brokers today in smaller clusters. As per usual, all sorts of deployment options are possible, including running in the same JVM. Let us see what issues we have with the above setup with the involvement of Zookeeper. This is the architecture that we would have traditionally use for such a microservice: 1. If you look at the post KIP-500, the metadata is stored in the Kafka cluster itself. In the post-ZK world, cluster membership is integrated with metadata updates. Brokers cannot continue to be members of the cluster if they cannot receive metadata updates. While it is still possible for a broker to be partitioned from a particular client, the broker will be removed from the cluster if it is partitioned from the controller. 通过 KIP-554, SCRAM 凭据可以通过 Kafka 协议进行管理，kafka-configs 工具使用了这个新的协议 API 以便在 Broker 端对 SCRAM 进行配置，这个也是 Kafka 移除 Zookeeper 项目的一部分。 KIP-497: 添加可以修改 ISR 的 Note that this diagram is slightly misleading. Other brokers besides the controller can and do communicate with ZooKeeper. So really, a line should be drawn from each broker to ZK. However, drawing that many lines would make the diagram difficult to read. Another issue which this diagram leaves out is that external command line tools and utilities can modify the state in ZooKeeper, without the involvement of the controller. As discussed earlier, these issues make it difficult to know whether the state in memory on the controller truly reflects the persistent state in ZooKeeper. All tools have been updated to not rely on ZooKeeper so this KIP proposes deprecating the --zookeeper flag to … We will meet with another topic. The Kafka Streams client library sees three new KIPs. Currently, the topic creation or deletion requires to get the full list of topics in the cluster from the Zookeeper metadata. This is fairly complicated and will require lots of code. When a broker is stopping, it is still running, but we are trying to migrate the partition leaders off of the broker. At the moment, Kafka still requires Zookeeper. Most of the time, the broker should only need to fetch the deltas, not the full state. However, if the broker is too far behind the active controller, or if the broker has no cached metadata at all, the controller will send a full metadata image rather than a series of deltas. ZooKeeperの依存関係はApache Kafkaから削除されます。KIP-500：ZooKeeperを自己管理メタデータクォーラムに置き換えるでの高レベルの議論を参照してください。 これらの取り組みには、いくつかのKafkaリリースと追加のKIPが必要 KIP-555: details about the ZooKeeper deprecation process in A single number, the offset, describes a consumer's position in the stream. Multiple consumers can quickly catch up to the latest state simply by replaying all the events newer than their current offset. The log establishes a clear ordering between events, and ensures that the consumers always move along a single timeline. KIP-500: Replace ZooKeeper with a Self-Managed Metadata Quorum: Currently, Kafka uses Apache Zookeeper to store topic and broker metadata as well as handle controller election. With KIP-500, we are going to see a Kafka cluster without the Zookeeper cluster where the metadata management will be done with Kafka itself. KIP-554: Add broker-side SCRAM configuration API. Currently, if a broker loses its ZooKeeper session, the controller removes it from the cluster metadata. In the post-ZooKeeper world, the active controller removes a broker from the cluster metadata if it has not sent a MetadataFetch heartbeat in a long enough time. Say goodbye to Kafka ZooKeeper dependency! With KIP-500, Kafka will include its own built-in consensus layer, removing the ZooKeeper dependency altogether.The next big milestone in this effort is coming in Apache Kafka 2.8.0Apache Kafka 2.8.0 Brokers enter the stopping state when they receive a SIGINT. This indicates that the system administrator wants to shut down the broker. He has successfully delivered multiple applications in retail, telco, and financial services domains. All tools have been updated to not rely on ZooKeeper so this KIP proposes deprecating the --zookeeper flag to … While this release will not remove ZooKeeper, it will eliminate most of the touch points where the rest of the system communicates with it. As much as possible, we will perform all access to ZooKeeper in the controller, rather than in other brokers, clients, or tools. Therefore, although ZooKeeper will still be required for the bridge release, it will be a well-isolated dependency. In order to present the big picture, I have mostly left out details like RPC formats, on-disk formats, and so on. This setup is a minimum for sustaining 1 Kafka broker failure. These efforts will take a few Kafka releases and additional KIPs. Post KIP-500, the metadata scalability increases which eventually improves the SCALABILITY of Kafka.