embedded kafka spring boot test

Spring Kafka brings the simple and typical Spring template programming model with a KafkaTemplate and Message-driven POJOs via @KafkaListenerannotation. The … If the broker is present, an embedded broker is started and configured automatically (as long as no broker URL is specified through configuration). Console. Spring-kafka-test embedded Kafka Server. The reason for this is that we need a way to inject the server address into our application, which as previously mentioned, is generated dynamically. This post talks about different ways in which we can test Spring Boot applications, using EmbeddedKafka and Awaitility. I am trying to write a unit test for a Kafka listener that I am developing using Spring Boot 2.x. Once the running embedded Kafka is running, there are a couple of tricks necessary, e.g. In this case, you will get the following exception: Caused by: java.lang.IllegalArgumentException: The class 'com.example.kafkatestsample.infrastructure.kafka.TestDomainEvent' is not in the trusted packages: [java.util, java.lang, com.example.kafkatestsample.event]. For Kafka’s words, take a look at the blog I wrote two days ago:Kafka installation and quick startIf you want to learn, start your own virtual machine, build your own environment manually, and buy a server if you have the conditions. Apache Kafkais a distributed and fault-tolerant stream processing system. Spring-kafka-test provides an embedded Kafka broker. Likewise, we'll now define a simple consumer bean which will listen to a Kafka topic and receives messages: Our simple consumer uses the @KafkaListener annotation on the receive method to listen to messages on a given topic. Above you can configure your serializers and de-serializers as you want. This is done in the background and we might not receive a message from our topic until this is done. There are a couple of properties available to influence the behavior and size of the embedded Kafka node: As a next step, you can autowire the running embedded Kafka instance. By adding module into classpath, you will get stateful service, like Couchbase or Kafka, auto-started and available for connection from your application service w/o wiring any additional code. The 2.4.0 kafka-clients are not binary compatible with Spring for Apache Kafka 2.3 so if you wish to use the 2.4.0 clients, you must upgrade to this version. However, the above code can start successfully if you already have the service environment of Kafka Server. This field is an instance of the KafkaContainer class that will prepare and manage the lifecycle of our container running Kafka. For the final piece of the jigsaw, we simply send a message to our test topic and verify that the message has been received and contains the name of our test topic. Apache Kafka is a powerful, distributed, fault-tolerant stream processing system. The 2.4.0 kafka-clients are not binary compatible with Spring for Apache Kafka 2.3 so if you wish to use the 2.4.0 clients, you must upgrade to this version. The first parameter is the name of your consumer group, the second is a flag to set auto commit and the last parameter is the EmbeddedKafkaBroker instance. With that in mind, let's go ahead and write our first integration test: Let's walk through the key parts of our test. In details, Spring Boot manages the creation of Kafka Streams. You can also check out the complete test source code at GitHub. In this section, we'll take a look at how to use an in-memory Kafka instance to run our tests against. The Spring Apache Kafka (spring-kafka) provides a high-level abstraction for Kafka-based messaging solutions. // tell Spring Boot Kafka auto-config about the embedded kafka endpoints properties = " spring.kafka.bootstrap-servers=${spring.embedded.kafka.brokers} " , // slice our unit test app context down to just these specific pieces Are you creative and passionate about software development? The number of Kafka servers to start. In this tutorial, we'll build on the previous one and learn how to write reliable, self-contained integration tests that don't rely on an external Kafka server running. The spring-boot-starter-test includes the dependencies for testing Spring Boot applications with libraries that include JUnit, Hamcrest and Mockito. This could have adverse effects on our test results. In case you are using Spring Boot, for a couple of services there exist an integration. Then we'll see how we can make use of the popular framework Testcontainers from our tests. Learn to create a spring boot application which is able to connect a given Apache Kafka broker instance. The EmbeddedKafkaRule constructor function takes the following values as parameters. Spring Boot - Apache Kafka - Apache Kafka is an open source project used to publish and subscribe the messages based on the fault-tolerant messaging system. We know that Kafka is built by Scala + Zookeeper and can download the deployment package from … Spring. Since we now have a consumer and a producer, we are actually able to produce messages: And also consume messages and doing assertions on them: For consuming records there are the following methods on KafkaTestUtils: The default timeout is 60 seconds, what is pretty long for testing. The good part is that no broker starts during tests, not even an embedded Kafka :) Moreover, the test is a pure JUnit test and requires no Spring context configuration. be careful:Be sure to install it … Since a new consumer subscribed to the topic, Kafka is triggering now a rebalance of our consumers. To start the embedded Kafka instance and the Spring Boot application, I used the SpawnProcessTask as the task type. Being a unit test, I don't want to start up a full Kafka server an instance of Zookeeper. The spring-kafka-test jar contains some useful utilities to assist with testing your applications. After execution the test you should close the consumer with consumer.close(). For testing I will show you how to use Embedded Kafka. Then we saw how to use Testcontainers to set up an external Kafka broker running inside a docker container from our tests. A dependency on spring-kafka is added. Let's define another integration test which will be quite similar to the one we saw in the previous section: Let's take a look at the differences this time around. The test blocks the main execution thread until the API returns the response. Integrating external services into an application is often challenging. see how Spring Boot minimizes configuration and boiler-plate for using Kafka; write a test that uses Embedded Kafka for reliability; I’ll be using a simple example application in order to demonstrate everything with working code. If you believe this class is safe to deserialize, please provide its name. The above expression is known as the SpEL (Spring Expression Language), and what it does here is it will get the value of spring.embedded.kafka.brokers if it exists or … High throughput: even very common hardware Kafka can support millions of messages per second. Also, learn to produce and consumer messages from a Kafka topic. If the serialization is only done by a trusted source, you can also enable trust all (*). This article contains a short How-To guide on setting up Embedded Kafka to be used for unit testing an application. In case you have inheritance and you have an abstract parent class or an interface your actual implementation might be in the test case. Although unlikely, it could also be that the port used from our test might be occupied, causing a failure. This is also known as Embedded Kafka. When we run our test, we'll see amongst the verbose Spring output: This confirms that our test is working properly. Now that we have our simple Kafka application using Spring Boot implemented let's see how we can write integration tests. The dependency spring-kafka-test we added previously contains some useful utilities to assist with testing our application. A working integration test using a Kafka docker container. You can solve that by adding the specific package or all packages as trusted: It's easy to test a Kafka integration once you have your setup working. In this article, we'll cover Spring support for Kafka and the level of abstractions it provides over native Kafka Java client APIs. We would like to avoid timing issues, therefore we have two possible options: We could configure our consumer to always start from the beginning. In addition to the normal Kafka dependencies you need to add the spring-kafka-test dependency: The most basic test is just to test the integration. Let's start by defining our application entry point: @SpringBootApplication @EnableAutoConfiguration public class KafkaProducerConsumerApplication { public static void main(String[] args) { SpringApplication.run(KafkaProducerConsumerApplication.class, args); } } The @EmbeddedKafka is providing a handy annotation to get started. See the appendix in the reference manual for how to override the jar versions, especially if you are using Spring Boot for dependency management and/or you are using the test embedded Kafka broker. Kafka. A sample project is here. The definition of my listener is very basic. By adding module into classpath, you will get stateful service, like Couchbase or Kafka, auto-started and available for connection from your application service w/o wiring any additional code. Is working since 2016 at mimacom as a Software Engineering. We can call consumer.poll(0), which would actually wait until we are subscribed, even with the timeout 0 (first parameter). For this reason, we provide a custom consumer and producer factory configuration using the class KafkaTestContainersConfiguration: We then reference this configuration via the @Import annotation at the beginning of our test. A JUnit 4 @Rule wrapper for the EmbeddedKafkaBroker is provided to create an embedded Kafka and an embedded Zookeeper server. We'll define these properties in our src/test/resources/application.yml file: This is the minimum set of properties that we need when working with an embedded instance of Kafka or a local broker. Spring Boot Embedded ActiveMQ Configuration. THE unique Spring Security education if you’re working with Java today. You can also check out the complete source code of my example on testing Kafka with Spring Boot and JUnit 5 in this GitHub Gist. The spring-kafka-test jar contains some useful utilities to assist with testing your applications. Kafka is a high-throughput distributed publish subscribe message system, which has the following characteristics: it provides message persistence through O (1) disk data structure, which can maintain long-term stable performance for even terabytes of message storage. Afterward, you are able to configure your consumer with the Spring wrapper DefaultKafkaConsumerFactory or with the Kafka Java API. Testing. Later you would like to have it to configure Kafka for the actual implementation. This blog post will show how you can setup your Kafka tests to use an embedded Kafka server. @SpringBootTest(properties) – overriding the Kafka broker address and port and using random port created by the embedded Kafka instead. In case you are using Spring Boot, for a couple of services there exist an integration. We achieve this by calling the getBootstrapServers() method, which will return the bootstrap server location: Now when we run our test, we should see that Testcontainers does several things: Again, this is confirmed by inspecting the test output: Presto! spring-kafka: 2.4.5.RELEASE spring-kafka-test: 2.4.5.RELEASE junit-jupiter: 5.5.2 java: 1.8 no specific version mentioned for the dependency for spring-boot-starter and spring-boot-starter-test my application is currently testing locally on a window machine. We're declaring the kafka field, which is a standard JUnit @ClassRule. With the running embedded Kafka, there are a couple of tricks necessary like the consumer.poll(0) and the addTrustedPackages that you would not necessarily experience when you are testing manually. In this article, we've learned about a couple of approaches for testing Kafka applications with Spring Boot. Those you would not necessarily experience when you are testing manually. It is fast, scalable and distrib Configuring the Kafka Producer is even easier than the Kafka Consumer: In case you don't have a EmbeddedKafkaBroker instance you could also use KafkaTestUtils.senderProps(String brokers) to get actual properties. Most of these are self-explanatory, but the one we should highlight of particular importance is the consumer property auto-offset-reset: earliest. We'll see later how we configure the test.topic from our tests. The guides on building REST APIs with Spring. To avoid port clashes, Testcontainers allocates a port number dynamically when our docker container starts. Most notably, it contains the EmbeddedKafkaBroker class. This rule starts the Kafka and Zookeeper servers on … Spring Boot can automatically configure a ConnectionFactory when it detects that ActiveMQ is available on the class-path. Steps we will follow: Create Spring boot application with Kafka dependencies Configure kafka broker instance in application.yaml Use KafkaTemplate to send messages to topic Use @KafkaListener […] So, I decided to use Spring Embedded Kafka. Do you want to achieve great things within our team. Therefore we would need to set the property AUTO_OFFSET_RESET_CONFIG to earliest: This would do the job pretty well in our simple example but has some disadvantages in case we would like to ignore some of the messages we have seen before. SPRING_EMBEDDED_KAFKA_BROKERS public static final java.lang.String SPRING_EMBEDDED_KAFKA_BROKERS See Also: Constant Field Values; SPRING_EMBEDDED_ZOOKEEPER_CONNECT public static final java.lang.String SPRING_EMBEDDED_ZOOKEEPER_CONNECT See Also: Constant Field Values; … In the first approach, we saw how to configure and use a local in-memory Kafka broker. A JUnit 4 @Rule wrapper for the EmbeddedKafkaBroker is provided to create an embedded Kafka … 2、Kafka. And in the previous post, We had developed a Spring Kafka Application with the auto-configuration supported by SpringBoot (from version 1.5). It will be bootstrapped before our first test case of this class is executed and killed after the last test case. Focus on the new OAuth2 stack in Spring Security 5. Awesome! Then we'll see how we can make use of the popular framework, key = null, value = Sending with our own simple KafkaProducer)', Starts a new container and waits for it to be ready, Finally, shuts down and deletes the container after our test finishes. While testing any synchronous application, it is all about “call and wait”. In a previous tutorial, we learned how to work with Spring and Kafka. The library kafka-streams-test-utils manages the interaction with the broker. Therefore you need to use Kafka to publish a message and afterward you could read the message from the topic. Our @EmbeddedKafka is now available in our test class. But when we need explicitly configure Kafka factories (Kafka Producer and Kafka Consumer) for development, how to do it? we invoke a particular API or endpoint and wait for the response. As always, the full source code of the article is available over on GitHub. Do you think unconventionally and act with initiative? Choosing the right messaging system during your architectural planning is always a challenge, yet one of the most important considerations to nail. Instead of doing the testing manually, the setup could be tested also automated. I have more dependencies than the one in your sample but are not Kafka related. We also include spring-kafka-test to have access to an embedded Kafka broker when running our unit test. Next, let's consider a producer bean that we'll use to send messages to a given Kafka topic: Our KafkaProducer bean defined above is merely a wrapper around the KafkaTemplate class. It is possible to restrict @SpringBootTest to the necessary classes. Run the Spring Boot integration test or unit test, many annoying DEBUG and INFO logs are displayed in the console. With that in mind, in this section, we'll see a variation on our previous approach to testing using the Testcontainers framework. Because of the timeout 0, we would not wait for our actual message which we haven't send yet. Where possible, we want to make use of default configuration values. Of course, we'll need to add the standard spring-kafka dependency to our pom.xml: Then we'll need two more dependencies specifically for our tests. In general, when writing clean integration tests, we shouldn't depend on external services that we might not be able to control or might suddenly stop working. Furthermore, the receive method stores the message content in our bean and decrements the count of the latch variable. Spring Kafka provides a variety of testing utilities to make writing integration tests easier. The Spring Kafka Test library provides an embedded Kafka broker that works great for this. We can use a JUnit @ClassRule annotation to create this Kafka broker. We're going to use a very light set of application configuration properties from our tests. Additionally, we configure a topic property with the value embedded-test-topic, which is the topic we'll use from our tests. You might like to specify a smaller timeout, the unit therefore is milliseconds. First, we start by decorating our test class with two pretty standard Spring annotations: Here comes the crucial part, we use the @EmbeddedKafka annotation to inject an instance of an EmbeddedKafkaBroker into our tests. With Spring Boot, it is only necessary to set the spring.kafka.producer.transaction-id-prefix property - Boot will automatically configure a KafkaTransactionManager bean and wire it into the listener container. You need to annotate your test class with at least the following annotations: Until now, the @SpringBootTest annotation is not really necessary. Moreover, there are several properties available we can use to configure the embedded Kafka node: Next, we auto-wire our consumer and producer classes and configure a topic to use the value from our application.properties. The high level overview of all the articles on the site. This class provides high-level thread-safe operations, such as sending data to the provided topic, which is exactly what we do in our send method. Similarly, if we're dependent on an external service, in this case, a running Kafka broker, we likely won't be able to set it up, control it and tear it down in the way we want from our tests. The canonical reference for building a production grade API with Spring. If you develop services using Spring Boot and maybe Spring Cloud and you do medium sized tests during build process, then this set of Spring Boot auto-configurations might be handy. Since Kafka is running on a random port, it's necessary to get the configuration for your producers and consumers: Now you are able to configure your consumer or producer: KafkaTestUtils.consumerProps is providing you almost all the properties you need. Instead of doing the testing manually, the setup could be tested also automated. First, we'll add the spring-kafka-test artifact: And finally, we'll add the Testcontainers Kafka dependency, which is also available over on Maven Central: Now that we have all the necessary dependencies configured, we can write a simple Spring Boot application using Kafka. Integrating external services into an application is often challenging. Either use your existing Spring Boot project or generate a new one on start.spring.io. Unit testing Kafka can be a pain, it seems a lot of overkill to have an entire Kafka cluster ready just for unit testing purposes, luckily, spring-kafka-test helps with this by providing an Embedded Kafka instance you can use to produce or consume messages. We now have a way to write self-contained, independent integration tests using an in-memory Kafka broker. Most notably, the @EmbeddedKafka annotation spins up an embedded broker (and zookeeper) available for tests.The address of the broker is set to the ${spring.embedded.kafka.brokers} property so that you can configure your consumers and producers appropriately. @EmbeddedKafka – to enable the embedded Kafka for the test class. Sometimes we might see small differences between a real external service vs. an embedded in-memory instance of a service that has been specifically provided for testing purposes. If you are writing services using Spring Boot (and maybe Spring Cloud) and you do medium sized tests during build process, then this set of Spring Boot auto-configurations might be handy. I’ll show you how I implemented it using Gradle and a Spring Boot application. Throughout this tutorial, the focus of our tests will be a simple producer-consumer Spring Boot Kafka application. Throughout this tutorial, the focus of our tests will be a simple producer-consumer Spring Boot Kafka application. bootstrapping the consumer and the addTrustedPackages. P.S Tested with Spring Boot 2. This blog post will show how you can setup your Kafka tests to use an embedded Kafka server. First, we'll start but looking at how to use and configure an embedded instance of Kafka. With this in mind, we make use of the @EnableAutoConfiguration annotation to auto-config our application. After reading this six-step guide, you will have a Spring Boot application with a Kafka producer to publish messages to your Kafka topic, as well as with a Kafka consumer to read those messages. The application is a simulation of electricity meters producing regular readings. First, we'll start but looking at how to use and configure an embedded instance of Kafka. "spring-kafka-test"includes an embedded Kafka server that can be created via a JUnit @ClassRule annotation. From no experience to actually building stuff​. See the appendix in the reference manual for how to override the jar versions, especially if you are using Spring Boot for dependency management and/or you are using the test embedded Kafka broker. We'll see how to instantiate and manage an external Apache Kafka broker hosted inside a Docker container from our integration test. This variable is a simple thread-safe counter field that we'll use later from our tests to ensure we successfully received a message. Let's start by defining our application entry point: As we can see, this is a standard Spring Boot application.
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