Spring Kafka lets you create new topics by declaring @Bean
s in your application context. This will require a bean of type KafkaAdmin
in the application context, which will be created automatically if using Spring Boot. You could define your topic as follows:
@Bean
public NewTopic myTopic() {
return TopicBuilder.name("my-topic")
.partitions(4)
.replicas(3)
.config(TopicConfig.RETENTION_MS_CONFIG, "1680000")
.build();
}
If you are not using Spring Boot, you'll additionally have to define the KafkaAdmin
bean:
@Bean
public KafkaAdmin admin() {
Map<String, Object> configs = new HashMap<>();
configs.put(AdminClientConfig.BOOTSTRAP_SERVERS_CONFIG,"localhost:9092");
return new KafkaAdmin(configs);
}
If you want to edit the configuration of an existing topic, you'll have to use the AdminClient
, here's the snippet to change the retention.ms
at a topic level:
Map<String, Object> config = new HashMap<>();
config.put(AdminClientConfig.BOOTSTRAP_SERVERS_CONFIG,"localhost:9092");
AdminClient client = AdminClient.create(config);
ConfigResource resource = new ConfigResource(ConfigResource.Type.TOPIC, "new-topic");
// Update the retention.ms value
ConfigEntry retentionEntry = new ConfigEntry(TopicConfig.RETENTION_MS_CONFIG, "1680000");
Map<ConfigResource, Config> updateConfig = new HashMap<>();
updateConfig.put(resource, new Config(Collections.singleton(retentionEntry)));
AlterConfigOp op = new AlterConfigOp(retentionEntry, AlterConfigOp.OpType.SET);
Map<ConfigResource, Collection<AlterConfigOp>> configs = new HashMap<>(1);
configs.put(resource, Arrays.asList(op));
AlterConfigsResult alterConfigsResult = client.incrementalAlterConfigs(configs);
alterConfigsResult.all();
The configuration can be set up automatically using this @PostConstruct
method that takes in NewTopic
beans.
@Autowired
private Set<NewTopic> topics;
@PostConstruct
public void reconfigureTopics() throws ExecutionException, InterruptedException {
try (final AdminClient adminClient = AdminClient.create(Map.of(AdminClientConfig.BOOTSTRAP_SERVERS_CONFIG, kafkaBootstrapServers))) {
adminClient.incrementalAlterConfigs(topics.stream()
.filter(topic -> topic.configs() != null)
.collect(Collectors.toMap(
topic -> new ConfigResource(ConfigResource.Type.TOPIC, topic.name()),
topic -> topic.configs().entrySet()
.stream()
.map(e -> new ConfigEntry(e.getKey(), e.getValue()))
.peek(ce -> log.debug("configuring {} {} = {}", topic.name(), ce.name(), ce.value()))
.map(ce -> new AlterConfigOp(ce, AlterConfigOp.OpType.SET))
.collect(Collectors.toList())
)))
.all()
.get();
}
}
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