dynamic switching between two kafkaTemplate objects

Question

I have two kafka clusters (Active-passive). I created two KafkaTemplate objects for producing events(one for each). I will keep using primary kafkaTemplate to send events as long as it is healthy. Incase of any issue, i want to dynamically switch over to second kafkaTemplate. I dont want to have an if condition to switch between objects to use to send( last resort)

Is there a way to dynamically switch objects?

Consumer side, we have MessageListenerContainers and we have setAutoStartUp api to manage start and stop of multiple listeners

Can someone help me with the producer?!

Answer 1

Simply implement your own KafkaOperations which delegates to active template and fails over when needed.

EDIT

For example:

public class DelegatingTemplate<K, V> implements KafkaOperations<K, V> {

    private final KafkaTemplate<String, String> template1;

    private final KafkaTemplate<String, String> template2;

    private volatile KafkaTemplate<String, String> currentTemplate;

    public DelegatingTemplate(KafkaTemplate<String, String> template1, KafkaTemplate<String, String> template2) {
        this.template1 = template1;
        this.template2 = template2;
        this.currentTemplate = template1;
    }

    public void switchTemplates(boolean primary) {
        this.currentTemplate = primary ? template1 : template2;
    }

    @Override
    public boolean isTransactional() {
        return this.currentTemplate.isTransactional();
    }

    @Override
    public ListenableFuture<SendResult<String, String>> sendDefault(String data) {
        return this.currentTemplate.sendDefault(data);
    }

    @Override
    public ListenableFuture<SendResult<String, String>> sendDefault(String key, String data) {
        return this.currentTemplate.sendDefault(key, data);
    }

    @Override
    public ListenableFuture<SendResult<String, String>> sendDefault(Integer partition, String key, String data) {
        return this.currentTemplate.sendDefault(partition, key, data);
    }

    @Override
    public ListenableFuture<SendResult<String, String>> sendDefault(Integer partition, Long timestamp, String key,
            String data) {
        return this.currentTemplate.sendDefault(partition, timestamp, key, data);
    }

    @Override
    public ListenableFuture<SendResult<String, String>> send(String topic, String data) {
        return this.currentTemplate.send(topic, data);
    }

    @Override
    public ListenableFuture<SendResult<String, String>> send(String topic, String key, String data) {
        return this.currentTemplate.send(topic, key, data);
    }

    @Override
    public ListenableFuture<SendResult<String, String>> send(String topic, Integer partition, String key, String data) {
        return this.currentTemplate.send(topic, partition, key, data);
    }

    @Override
    public ListenableFuture<SendResult<String, String>> send(String topic, Integer partition, Long timestamp,
            String key, String data) {
        return this.currentTemplate.send(topic, partition, timestamp, key, data);
    }

    @Override
    public ListenableFuture<SendResult<String, String>> send(ProducerRecord<String, String> record) {
        return this.currentTemplate.send(record);
    }

    @Override
    public ListenableFuture<SendResult<String, String>> send(Message<?> message) {
        return this.currentTemplate.send(message);
    }

    @Override
    public List<PartitionInfo> partitionsFor(String topic) {
        return this.currentTemplate.partitionsFor(topic);
    }

    @Override
    public Map<MetricName, ? extends Metric> metrics() {
        return this.currentTemplate.metrics();
    }

    @Override
    public <T> T execute(ProducerCallback<String, String, T> callback) {
        return this.currentTemplate.execute(callback);
    }

    @Override
    public <T> T executeInTransaction(OperationsCallback<String, String, T> callback) {
        return this.currentTemplate.executeInTransaction(callback);
    }

    @Override
    public String toString() {
        return this.currentTemplate.toString();
    }

    @Override
    public void flush() {
        this.currentTemplate.flush();
    }

    @Override
    public void sendOffsetsToTransaction(Map<TopicPartition, OffsetAndMetadata> offsets) {
        this.currentTemplate.sendOffsetsToTransaction(offsets);
    }

    @Override
    public void sendOffsetsToTransaction(Map<TopicPartition, OffsetAndMetadata> offsets, String consumerGroupId) {
        this.currentTemplate.sendOffsetsToTransaction(offsets, consumerGroupId);
    }

}