feat: configurable retry interval after retriable exceptions (#54)

If the connector throws a retriable exception, there is no need
for Connect's Kafka consumer to wait for as long to re-consume
messages from the Kafka topic. It's therefore helpful to be able
to specify that the consumer should use a shorter timeout for
polls immediately following a retriable exception.

This commit introduces a new config parameter mq.retry.backoff.ms
which allows this to be controlled.

By default, it is set to 1 minute, which is how long it
currently waits.

Signed-off-by: Dale Lane <dale.lane@uk.ibm.com>

Author: dalelane

Dockerfile

@@ -10,7 +10,7 @@ COPY --chown=esuser:esgroup --from=builder /opt/kafka/libs/ /opt/kafka/libs/
 COPY --chown=esuser:esgroup --from=builder /opt/kafka/config/connect-distributed.properties /opt/kafka/config/
 COPY --chown=esuser:esgroup --from=builder /opt/kafka/config/connect-log4j.properties /opt/kafka/config/
 RUN mkdir /opt/kafka/logs && chown esuser:esgroup /opt/kafka/logs
-COPY --chown=esuser:esgroup target/kafka-connect-mq-sink-1.4.0-jar-with-dependencies.jar /opt/kafka/libs/
+COPY --chown=esuser:esgroup target/kafka-connect-mq-sink-1.5.0-jar-with-dependencies.jar /opt/kafka/libs/
 
 WORKDIR /opt/kafka
 

README.md

@@ -98,13 +98,13 @@ curl -X POST -H "Content-Type: application/json" http://localhost:8083/connector
 This repository includes an example Dockerfile to run Kafka Connect in distributed mode. It also adds in the MQ sink connector as an available connector plugin. It uses the default `connect-distributed.properties` and `connect-log4j.properties` files.
 
 1. `mvn clean package`
-1. `docker build -t kafkaconnect-with-mq-sink:1.4.0 .`
-1. `docker run -p 8083:8083 kafkaconnect-with-mq-sink:1.4.0`
+1. `docker build -t kafkaconnect-with-mq-sink:1.5.0 .`
+1. `docker run -p 8083:8083 kafkaconnect-with-mq-sink:1.5.0`
 
 **NOTE:** To provide custom properties files create a folder called `config` containing the `connect-distributed.properties` and `connect-log4j.properties` files and use a Docker volume to make them available when running the container like this:
 
 ``` shell
-docker run -v $(pwd)/config:/opt/kafka/config -p 8083:8083 kafkaconnect-with-mq-sink:1.4.0
+docker run -v $(pwd)/config:/opt/kafka/config -p 8083:8083 kafkaconnect-with-mq-sink:1.5.0
 ```
 
 To start the MQ connector, you can use `config/mq-sink.json` in this repository after replacing all placeholders and use a command like this:
@@ -312,6 +312,7 @@ The configuration options for the Kafka Connect sink connector for IBM MQ are as
 | mq.message.builder.partition.property   | The JMS message property to set from the Kafka partition               | string  |                | Blank or valid JMS property name  |
 | mq.message.builder.offset.property      | The JMS message property to set from the Kafka offset                  | string  |                | Blank or valid JMS property name  |
 | mq.reply.queue                          | The name of the reply-to queue                                         | string  |                | MQ queue name or queue URI        |
+| mq.retry.backoff.ms                     | Wait time, in milliseconds, before retrying after retriable exceptions | long    | 60000          | [0,...]                           |
 
 
 ### Using a CCDT file

pom.xml

@@ -20,7 +20,7 @@
   <groupId>com.ibm.eventstreams.connect</groupId>
   <artifactId>kafka-connect-mq-sink</artifactId>
   <packaging>jar</packaging>
-  <version>1.4.0</version>
+  <version>1.5.0</version>
   <name>kafka-connect-mq-sink</name>
   <organization>
     <name>IBM Corporation</name>

src/main/java/com/ibm/eventstreams/connect/mqsink/MQSinkConnector.java

@@ -147,7 +147,12 @@ public class MQSinkConnector extends SinkConnector {
     public static final String CONFIG_DOCUMENTATION_KAFKA_HEADERS_COPY_TO_JMS_PROPERTIES = "Whether to copy Kafka headers to JMS message properties.";
     public static final String CONFIG_DISPLAY_KAFKA_HEADERS_COPY_TO_JMS_PROPERTIES = "Copy Kafka headers to JMS message properties";
 
-    public static String VERSION = "1.4.0";
+    public static final String CONFIG_NAME_MQ_RETRY_BACKOFF_MS = "mq.retry.backoff.ms";
+    public static final String CONFIG_DOCUMENTATION_MQ_RETRY_BACKOFF_MS = "Time to wait, in milliseconds, before retrying after retriable exceptions";
+    public static final String CONFIG_DISPLAY_MQ_RETRY_BACKOFF_MS = "Retry backoff (ms)";
+
+
+    public static String VERSION = "1.5.0";
 
     private Map<String, String> configProps;
 
@@ -336,6 +341,10 @@ public class MQSinkConnector extends SinkConnector {
                       CONFIG_DOCUMENTATION_KAFKA_HEADERS_COPY_TO_JMS_PROPERTIES, CONFIG_GROUP_MQ, 27, Width.SHORT,
                       CONFIG_DISPLAY_KAFKA_HEADERS_COPY_TO_JMS_PROPERTIES);
 
+        config.define(CONFIG_NAME_MQ_RETRY_BACKOFF_MS, Type.LONG, 60000, Range.between(0L, 99999999900L), Importance.LOW,
+                      CONFIG_DOCUMENTATION_MQ_RETRY_BACKOFF_MS, CONFIG_GROUP_MQ, 28, Width.SHORT,
+                      CONFIG_DISPLAY_MQ_RETRY_BACKOFF_MS);
+
         return config;
     }
 }

src/main/java/com/ibm/eventstreams/connect/mqsink/MQSinkTask.java

@@ -21,6 +21,7 @@
 
 import org.apache.kafka.clients.consumer.OffsetAndMetadata;
 import org.apache.kafka.common.TopicPartition;
+import org.apache.kafka.connect.errors.RetriableException;
 import org.apache.kafka.connect.sink.SinkRecord;
 import org.apache.kafka.connect.sink.SinkTask;
 
@@ -32,6 +33,8 @@ public class MQSinkTask extends SinkTask {
 
     private JMSWriter writer;
 
+    private long retryBackoffMs = 60000;
+
     public MQSinkTask() {
     }
 
@@ -61,6 +64,13 @@ public MQSinkTask() {
             log.debug("Task props entry {} : {}", entry.getKey(), value);
         }
 
+        // check if a custom retry time is provided
+        String retryBackoffMsStr = props.get(MQSinkConnector.CONFIG_NAME_MQ_RETRY_BACKOFF_MS);
+        if (retryBackoffMsStr != null) {
+            retryBackoffMs = Long.parseLong(retryBackoffMsStr);
+        }
+        log.debug("Setting retry backoff {}", retryBackoffMs);
+
         // Construct a writer to interface with MQ
         writer = new JMSWriter();
         writer.configure(props);
@@ -85,12 +95,19 @@ public MQSinkTask() {
     @Override public void put(Collection<SinkRecord> records) {
         log.trace("[{}] Entry {}.put, records.size={}", Thread.currentThread().getId(), this.getClass().getName(), records.size());
 
-        for (SinkRecord r: records) {
-            log.debug("Putting record for topic {}, partition {} and offset {}", r.topic(), r.kafkaPartition(), r.kafkaOffset());
-            writer.send(r);
+        try {
+            for (SinkRecord r: records) {
+                log.debug("Putting record for topic {}, partition {} and offset {}", r.topic(), r.kafkaPartition(), r.kafkaOffset());
+                writer.send(r);
+            }
+
+            writer.commit();
+        }
+        catch (RetriableException rte) {
+            context.timeout(retryBackoffMs);
+            throw rte;
         }
 
-        writer.commit();
         log.trace("[{}]  Exit {}.put", Thread.currentThread().getId(), this.getClass().getName());
     }