kafka_neu-1778570057504.zip-extract/kafka-4.2.0-src/docs/getting-started/quickstart.md

Path
kafka_neu-1778570057504.zip-extract/kafka-4.2.0-src/docs/getting-started/quickstart.md
Status
scanned
Type
file
Name
quickstart.md
Extension
.md
Programming language

      
    
Mime type
text/plain
File type
exported SGML document, UTF-8 Unicode text, with very long lines
Tag

      
    
Rootfs path

      
    
Size
11936 (11.7 KB)
MD5
386476b39a3cc60b47e7d7703de85e6c
SHA1
e45a36c473cd7421a947612ce917d9c7c6d47c33
SHA256
2614f1a1e726fcc14c3b516d1334f8700a3450856625b00e90ee23b9ab00d591
SHA512

      
    
SHA1_git
25061e31d16608acd7804dec66dd12692a3c1ca9
Is binary

      
    
Is text
True
Is archive

      
    
Is media

      
    
Is legal

      
    
Is manifest

      
    
Is readme

      
    
Is top level

      
    
Is key file

      
    
quickstart.md | 11.7 KB |

--- title: Quick Start description: weight: 3 tags: ['kafka', 'docs'] aliases: keywords: type: docs --- <!-- Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. --> ## Step 1: Get Kafka [Download](https://www.apache.org/dyn/closer.cgi?path=/kafka/4.2.0/kafka_2.13-4.2.0.tgz) the latest Kafka release and extract it: $ tar -xzf kafka_2.13-4.2.0.tgz $ cd kafka_2.13-4.2.0 ## Step 2: Start the Kafka environment NOTE: Your local environment must have Java 17+ installed. Kafka can be run using local scripts and downloaded files or the docker image. ### Using downloaded files Generate a Cluster UUID $ KAFKA_CLUSTER_ID="$(bin/kafka-storage.sh random-uuid)" Format Log Directories $ bin/kafka-storage.sh format --standalone -t $KAFKA_CLUSTER_ID -c config/server.properties Start the Kafka Server $ bin/kafka-server-start.sh config/server.properties Once the Kafka server has successfully launched, you will have a basic Kafka environment running and ready to use. ### Using JVM Based Apache Kafka Docker Image Get the Docker image: $ docker pull apache/kafka:4.2.0 Start the Kafka Docker container: $ docker run -p 9092:9092 apache/kafka:4.2.0 ### Using GraalVM Based Native Apache Kafka Docker Image Get the Docker image: $ docker pull apache/kafka-native:4.2.0 Start the Kafka Docker container: $ docker run -p 9092:9092 apache/kafka-native:4.2.0 ## Step 3: Create a topic to store your events Kafka is a distributed _event streaming platform_ that lets you read, write, store, and process [_events_](/documentation/#messages) (also called _records_ or _messages_ in the documentation) across many machines. Example events are payment transactions, geolocation updates from mobile phones, shipping orders, sensor measurements from IoT devices or medical equipment, and much more. These events are organized and stored in [_topics_](/documentation/#intro_concepts_and_terms). Very simplified, a topic is similar to a folder in a filesystem, and the events are the files in that folder. So before you can write your first events, you must create a topic. Open another terminal session and run: $ bin/kafka-topics.sh --create --topic quickstart-events --bootstrap-server localhost:9092 All of Kafka's command line tools have additional options: run the `kafka-topics.sh` command without any arguments to display usage information. For example, it can also show you [details such as the partition count](/documentation/#intro_concepts_and_terms) of the new topic: $ bin/kafka-topics.sh --describe --topic quickstart-events --bootstrap-server localhost:9092 Topic: quickstart-events TopicId: NPmZHyhbR9y00wMglMH2sg PartitionCount: 1 ReplicationFactor: 1 Configs: Topic: quickstart-events Partition: 0 Leader: 0 Replicas: 0 Isr: 0 ## Step 4: Write some events into the topic A Kafka client communicates with the Kafka brokers via the network for writing (or reading) events. Once received, the brokers will store the events in a durable and fault-tolerant manner for as long as you need—even forever. Run the console producer client to write a few events into your topic. By default, each line you enter will result in a separate event being written to the topic. $ bin/kafka-console-producer.sh --topic quickstart-events --bootstrap-server localhost:9092 >This is my first event >This is my second event You can stop the producer client with `Ctrl-C` at any time. ## Step 5: Read the events Open another terminal session and run the console consumer client to read the events you just created: $ bin/kafka-console-consumer.sh --topic quickstart-events --from-beginning --bootstrap-server localhost:9092 This is my first event This is my second event You can stop the consumer client with `Ctrl-C` at any time. Feel free to experiment: for example, switch back to your producer terminal (previous step) to write additional events, and see how the events immediately show up in your consumer terminal. Because events are durably stored in Kafka, they can be read as many times and by as many consumers as you want. You can easily verify this by opening yet another terminal session and re-running the previous command again. ## Step 6: Import/export your data as streams of events with Kafka Connect You probably have lots of data in existing systems like relational databases or traditional messaging systems, along with many applications that already use these systems. [Kafka Connect](/documentation/#connect) allows you to continuously ingest data from external systems into Kafka, and vice versa. It is an extensible tool that runs _connectors_ , which implement the custom logic for interacting with an external system. It is thus very easy to integrate existing systems with Kafka. To make this process even easier, there are hundreds of such connectors readily available. In this quickstart we'll see how to run Kafka Connect with simple connectors that import data from a file to a Kafka topic and export data from a Kafka topic to a file. First, make sure to add `connect-file-4.2.0.jar` to the `plugin.path` property in the Connect worker's configuration. For the purpose of this quickstart we'll use a relative path and consider the connectors' package as an uber jar, which works when the quickstart commands are run from the installation directory. However, it's worth noting that for production deployments using absolute paths is always preferable. See [plugin.path](../../configuration/kafka-connect-configs/#connectconfigs_plugin.path) for a detailed description of how to set this config. Edit the `config/connect-standalone.properties` file, add or change the `plugin.path` configuration property match the following, and save the file: $ echo "plugin.path=libs/connect-file-4.2.0.jar" >> config/connect-standalone.properties Then, start by creating some seed data to test with: $ echo -e "foo bar" > test.txt Or on Windows: $ echo foo > test.txt $ echo bar >> test.txt Next, we'll start two connectors running in _standalone_ mode, which means they run in a single, local, dedicated process. We provide three configuration files as parameters. The first is always the configuration for the Kafka Connect process, containing common configuration such as the Kafka brokers to connect to and the serialization format for data. The remaining configuration files each specify a connector to create. These files include a unique connector name, the connector class to instantiate, and any other configuration required by the connector. $ bin/connect-standalone.sh config/connect-standalone.properties config/connect-file-source.properties config/connect-file-sink.properties These sample configuration files, included with Kafka, use the default local cluster configuration you started earlier and create two connectors: the first is a source connector that reads lines from an input file and produces each to a Kafka topic and the second is a sink connector that reads messages from a Kafka topic and produces each as a line in an output file. During startup you'll see a number of log messages, including some indicating that the connectors are being instantiated. Once the Kafka Connect process has started, the source connector should start reading lines from `test.txt` and producing them to the topic `connect-test`, and the sink connector should start reading messages from the topic `connect-test` and write them to the file `test.sink.txt`. We can verify the data has been delivered through the entire pipeline by examining the contents of the output file: $ more test.sink.txt foo bar Note that the data is being stored in the Kafka topic `connect-test`, so we can also run a console consumer to see the data in the topic (or use custom consumer code to process it): $ bin/kafka-console-consumer.sh --bootstrap-server localhost:9092 --topic connect-test --from-beginning {"schema":{"type":"string","optional":false},"payload":"foo"} {"schema":{"type":"string","optional":false},"payload":"bar"} … The connectors continue to process data, so we can add data to the file and see it move through the pipeline: $ echo "Another line" >> test.txt You should see the line appear in the console consumer output and in the sink file. ## Step 7: Process your events with Kafka Streams Once your data is stored in Kafka as events, you can process the data with the [Kafka Streams](/documentation/streams) client library for Java/Scala. It allows you to implement mission-critical real-time applications and microservices, where the input and/or output data is stored in Kafka topics. Kafka Streams combines the simplicity of writing and deploying standard Java and Scala applications on the client side with the benefits of Kafka's server-side cluster technology to make these applications highly scalable, elastic, fault-tolerant, and distributed. The library supports exactly-once processing, stateful operations and aggregations, windowing, joins, processing based on event-time, and much more. To give you a first taste, here's how one would implement the popular `WordCount` algorithm: KStream<String, String> textLines = builder.stream("quickstart-events"); KTable<String, Long> wordCounts = textLines .flatMapValues(line -> Arrays.asList(line.toLowerCase().split(" "))) .groupBy((keyIgnored, word) -> word) .count(); wordCounts.toStream().to("output-topic", Produced.with(Serdes.String(), Serdes.Long())); The [Kafka Streams demo](/documentation/streams/quickstart) and the [app development tutorial](/42/documentation/streams/tutorial) demonstrate how to code and run such a streaming application from start to finish. ## Step 8: Terminate the Kafka environment Now that you reached the end of the quickstart, feel free to tear down the Kafka environment—or continue playing around. 1. Stop the producer and consumer clients with `Ctrl-C`, if you haven't done so already. 2. Stop the Kafka broker with `Ctrl-C`. If you also want to delete any data of your local Kafka environment including any events you have created along the way, run the command: $ rm -rf /tmp/kafka-logs /tmp/kraft-combined-logs ## Congratulations! You have successfully finished the Apache Kafka quickstart. To learn more, we suggest the following next steps: * Read through the brief [Introduction](/intro) to learn how Kafka works at a high level, its main concepts, and how it compares to other technologies. To understand Kafka in more detail, head over to the [Documentation](/documentation/). * Browse through the [Use Cases](/powered-by) to learn how other users in our world-wide community are getting value out of Kafka. * Join a [local Kafka meetup group](/events) and [watch talks from Kafka Summit](https://kafka-summit.org/past-events/), the main conference of the Kafka community.
Detected license expression
apache-2.0
Detected license expression (SPDX)
Apache-2.0
Percentage of license text
6.68
Copyrights

      
    
Holders

      
    
Authors

      
    
License detections License expression License expression SPDX
apache_2_0-4bde3f57-78aa-4201-96bf-531cba09e7de apache-2.0 Apache-2.0
URL Start line End line
http://www.apache.org/licenses/LICENSE-2.0 19 19
https://www.apache.org/dyn/closer.cgi?path=/kafka/4.2.0/kafka_2.13-4.2.0.tgz 31 31
https://kafka-summit.org/past-events 226 226