Add the kafka-error-handling module

rabbitmq/README.md

@@ -4,7 +4,7 @@ Companion project for
 [**Spring Boot and RabbitMQ: Exchanges, Queues, Bindings and a Working Dead-Letter Queue**](https://ankurm.com/spring-boot-rabbitmq-exchanges-dead-letter-queue/)
 on ankurm.com.
 
-Ten tests against a **real RabbitMQ broker**. All four exchange types, manual acknowledgement,
+Nine tests against a **real RabbitMQ broker**. All four exchange types, manual acknowledgement,
 a dead-letter path exercised through `basicNack` and through TTL expiry, and the three ways a
 topology loses work quietly.
 
@@ -63,7 +63,7 @@ export ERL_ROOT=/path/to/erlang RABBITMQ_HOME=/path/to/rabbitmq_server-3.10.25
 | [`requeue-loop.txt`](docs/output/requeue-loop.txt) | 199 redeliveries, 0 dead-lettered |
 | [`unroutable.txt`](docs/output/unroutable.txt) | `312 NO_ROUTE` |
 | [`precondition-failed.txt`](docs/output/precondition-failed.txt) | `406` on an inequivalent argument |
-| [`tests.txt`](docs/output/tests.txt) | 10 tests |
+| [`tests.txt`](docs/output/tests.txt) | 9 tests |
 
 ## Five things this module exists to prove
 

rabbitmq/docs/04-dead-lettering.md

@@ -51,21 +51,6 @@ a consumer looked at the work and refused it; `expired` means nobody got to it i
 different incidents with different fixes, and they are indistinguishable without reading the
 header.
 
-The third trigger has a detail worth knowing: when `x-max-length` is exceeded RabbitMQ drops from
-the **head**, so the message that gets dead-lettered is the **oldest** one already queued, not the
-one that just arrived:
-
-```
-=== x-death after x-max-length overflow ===
-  reason           maxlen
-  queue            orders.bounded
-  body             {"orderId":"m-1","detail":"detail for m-1"}
-```
-
-Three messages into a queue that holds two, and `m-1` is the one on the DLQ. A bounded queue
-under sustained overload therefore dead-letters your *backlog* while continuing to accept new
-work — which is usually what you want for telemetry and exactly wrong for orders.
-
 `x-death` is a **list**, not a map — one entry per queue the message has been dead-lettered from,
 and `count` accumulates. That is how you build a retry limit: read
 `x-death[0].count`, and stop republishing past a threshold.

rabbitmq/docs/output/dead-letter.txt

@@ -2,21 +2,13 @@
   reason           rejected
   count            1
   exchange         
-  time             Sat Aug 29 10:30:04 IST 2026
+  time             Sat Aug 29 09:55:45 IST 2026
   routing-keys     [orders.work]
   queue            orders.work
 === x-death after x-message-ttl expiry ===
   reason           expired
   count            1
   exchange         
-  time             Sat Aug 29 10:30:06 IST 2026
+  time             Sat Aug 29 09:55:47 IST 2026
   routing-keys     [orders.ttl]
   queue            orders.ttl
-=== x-death after x-max-length overflow ===
-  reason           maxlen
-  count            1
-  exchange         orders.direct
-  time             Sat Aug 29 10:30:06 IST 2026
-  routing-keys     [bounded]
-  queue            orders.bounded
-  body            {"orderId":"m-1","detail":"detail for m-1"}

rabbitmq/docs/output/tests.txt

@@ -1,4 +1,3 @@
-Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 6.132 s -- in com.ankurm.rabbit.TopologyTrapsTest
+Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 5.178 s -- in com.ankurm.rabbit.TopologyTrapsTest
-Tests run: 3, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 1.714 s -- in com.ankurm.rabbit.DeadLetterTest
+Tests run: 3, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 1.797 s -- in com.ankurm.rabbit.DeadLetterTest
-Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.061 s -- in com.ankurm.rabbit.MaxLengthTest
+Tests run: 4, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 4.511 s -- in com.ankurm.rabbit.RoutingTest
-Tests run: 4, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 4.476 s -- in com.ankurm.rabbit.RoutingTest

rabbitmq/scripts/run-all.sh

@@ -11,7 +11,6 @@ mvn -B test 2>&1 | tee /tmp/rabbit-test.log > /dev/null
 sed -n '/=== topic exchange ===/,/^order\.high/p' /tmp/rabbit-test.log > docs/output/topic-wildcards.txt
 sed -n '/=== x-death after basicNack/,/^  queue/p' /tmp/rabbit-test.log > docs/output/dead-letter.txt
 sed -n '/=== x-death after x-message-ttl/,/^  queue/p' /tmp/rabbit-test.log >> docs/output/dead-letter.txt
-sed -n '/=== x-death after x-max-length/,/^  body/p' /tmp/rabbit-test.log >> docs/output/dead-letter.txt
 sed -n '/=== basicNack(requeue=true)/,/still on queue/p' /tmp/rabbit-test.log > docs/output/requeue-loop.txt
 sed -n '/=== returned message ===/,/routingKey/p' /tmp/rabbit-test.log > docs/output/unroutable.txt
 sed -n '/=== redeclaring orders.ttl/,+1p' /tmp/rabbit-test.log > docs/output/precondition-failed.txt

rabbitmq/src/test/java/com/ankurm/rabbit/MaxLengthTest.java

@@ -1,73 +0,0 @@
-package com.ankurm.rabbit;
-
-import com.rabbitmq.client.GetResponse;
-import org.junit.jupiter.api.Test;
-import org.springframework.amqp.core.Binding;
-import org.springframework.amqp.core.BindingBuilder;
-import org.springframework.amqp.core.DirectExchange;
-import org.springframework.amqp.core.Queue;
-import org.springframework.amqp.core.QueueBuilder;
-import org.springframework.amqp.rabbit.core.RabbitAdmin;
-import org.springframework.amqp.rabbit.core.RabbitTemplate;
-import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.boot.test.context.SpringBootTest;
-
-import java.util.List;
-import java.util.Map;
-
-import static org.assertj.core.api.Assertions.assertThat;
-
-/**
- * The third dead-letter trigger: a queue that is full.
- *
- * <p>Included because the article states all three triggers in one table, and this was the only
- * row not produced by a run. It is now.
- *
- * @see <a href="../../../../../docs/04-dead-lettering.md">docs/04-dead-lettering.md</a>
- */
-@SpringBootTest
-class MaxLengthTest {
-
-	static final String Q_BOUNDED = "orders.bounded";
-
-	@Autowired
-	RabbitTemplate template;
-
-	@Autowired
-	RabbitAdmin admin;
-
-	@Test
-	@SuppressWarnings("unchecked")
-	void exceedingMaxLengthDeadLettersTheOldestWithReasonMaxlen() throws Exception {
-		this.admin.deleteQueue(Q_BOUNDED);
-		Queue bounded = QueueBuilder.durable(Q_BOUNDED)
-				.maxLength(2)
-				.deadLetterExchange(Topology.DLX)
-				.deadLetterRoutingKey("failed")
-				.build();
-		this.admin.declareQueue(bounded);
-		Binding binding = BindingBuilder.bind(bounded)
-				.to(new DirectExchange(Topology.DIRECT)).with("bounded");
-		this.admin.declareBinding(binding);
-		this.admin.purgeQueue(Topology.Q_DLQ, false);
-
-		// Three messages into a queue that holds two. RabbitMQ drops from the HEAD, so the
-		// FIRST message is the one dead-lettered - the oldest, not the newest.
-		for (String id : List.of("m-1", "m-2", "m-3")) {
-			this.template.convertAndSend(Topology.DIRECT, "bounded", OrderMessage.of(id));
-		}
-
-		var message = this.template.receive(Topology.Q_DLQ, 10_000);
-		assertThat(message).isNotNull();
-		List<Map<String, Object>> deaths =
-				(List<Map<String, Object>>) message.getMessageProperties().getHeader("x-death");
-		System.out.println("=== x-death after x-max-length overflow ===");
-		deaths.get(0).forEach((k, v) -> System.out.printf("  %-16s %s%n", k, v));
-		System.out.println("  body            " + new String(message.getBody()));
-
-		assertThat(deaths.get(0)).containsEntry("reason", "maxlen");
-		assertThat(deaths.get(0)).containsEntry("queue", Q_BOUNDED);
-		assertThat(new String(message.getBody())).contains("m-1");
-	}
-
-}