Shadow netty jars to avoid conflicts with other gem netty dependencies

.gitignore

@@ -11,3 +11,4 @@ deploy.docs.sh
 .ruby-version
 .idea
 spec/examples.txt
+target/

AGENTS.md

@@ -4,7 +4,28 @@
 
 This is March Hare, a JRuby AMQP 0-9-1 client for RabbitMQ built on top of the
 [RabbitMQ Java client](https://github.com/rabbitmq/rabbitmq-java-client).
-The Java client and its dependencies are bundled as JARs under `lib/ext`.
+The Java client and its dependencies are bundled as a single shaded JAR under `lib/ext`.
+
+### Bundled JARs and the Maven shade build
+
+`lib/ext/rabbitmq-client-netty-shaded.jar` is a shaded uber-JAR produced by `mvn package` using the
+Maven Shade plugin (see `pom.xml`).  It contains the RabbitMQ Java client together with
+all Netty modules.  All Netty classes are relocated from `io.netty.*` to
+`com.rabbitmq.marchhare.shaded.netty.*` so that other JRuby gems bundling a different
+Netty version on the same JVM (e.g. Logstash plugins) cannot conflict with march_hare's
+own Netty.
+
+The SLF4J JARs (`slf4j-api.jar`, `slf4j-simple.jar`) are kept as separate files and are
+**not** shaded — this lets the RabbitMQ client's log output flow through whatever SLF4J
+backend the user's application configures.
+
+**To update the RabbitMQ client or Netty version:**
+ 1. Edit the `<version>` of `com.rabbitmq:amqp-client` in `pom.xml` (Netty is pulled in
+    transitively at whatever version the client requires)
+ 2. Run `mvn package` (or `rake jars:build`) — this writes the new JAR to `lib/ext/rabbitmq-client-netty-shaded.jar`
+ 3. Download the matching `slf4j-api` and `slf4j-simple` JARs from Maven Central if the
+    SLF4J version changed, and replace the files in `lib/ext/`
+ 4. Commit all changed files under `lib/ext/` together with `pom.xml`
 
 ## Change Log
 

Rakefile

@@ -4,3 +4,11 @@ require 'bundler'
 
 
 Bundler::GemHelper.install_tasks
+
+namespace :jars do
+  desc 'Rebuild lib/ext/rabbitmq-client-netty-shaded.jar via Maven (run after bumping amqp-client or Netty versions in pom.xml)'
+  task :build do
+    sh 'mvn package -q'
+    puts 'Built lib/ext/rabbitmq-client-netty-shaded.jar'
+  end
+end

lib/march_hare.rb

@@ -6,15 +6,11 @@
 require 'ext/slf4j-api'
 require 'ext/slf4j-simple'
 
-# Modern RabbitMQ Java client depends on Netty
-require 'ext/netty-common'
-require 'ext/netty-buffer'
-require 'ext/netty-resolver'
-require 'ext/netty-transport'
-require 'ext/netty-codec-base'
-require 'ext/netty-handler'
-
-require 'ext/rabbitmq-client'
+# Single shaded JAR bundling the RabbitMQ Java client together with all Netty
+# dependencies.  Netty classes are relocated from io.netty.* to
+# com.rabbitmq.marchhare.shaded.netty.* so they cannot conflict with other gems
+# (e.g. Logstash plugins) that bundle a different Netty version on the same JVM.
+require 'ext/rabbitmq-client-netty-shaded'
 
 require 'march_hare/version'
 require 'march_hare/exceptions'

pom.xml

@@ -0,0 +1,96 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+
+  <groupId>com.rabbitmq</groupId>
+  <artifactId>march-hare-shaded</artifactId>
+  <version>1.0.0</version>
+  <packaging>jar</packaging>
+  <description>Shaded JAR bundling the RabbitMQ Java client with Netty relocated to a private
+    namespace, so that other JRuby gems shipping their own Netty version do not conflict.</description>
+
+  <!--
+    Run `mvn package` to regenerate lib/ext/rabbitmq-client-netty-shaded.jar after bumping dependency versions.
+    The output JAR is committed to git so gem consumers do not need Maven.
+  -->
+
+  <dependencies>
+    <dependency>
+      <groupId>com.rabbitmq</groupId>
+      <artifactId>amqp-client</artifactId>
+      <!-- Keep in sync with ChangeLog.md / version bump commits -->
+      <version>5.36.0</version>
+    </dependency>
+  </dependencies>
+
+  <build>
+    <plugins>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-shade-plugin</artifactId>
+        <version>3.6.0</version>
+        <executions>
+          <execution>
+            <phase>package</phase>
+            <goals>
+              <goal>shade</goal>
+            </goals>
+            <configuration>
+              <createDependencyReducedPom>false</createDependencyReducedPom>
+              <!-- Write directly into lib/ext so the gemspec git ls-files picks it up -->
+              <outputFile>${project.basedir}/lib/ext/rabbitmq-client-netty-shaded.jar</outputFile>
+
+              <relocations>
+                <!--
+                  Relocate every io.netty class to a private package so that other gems
+                  bundling a different Netty version do not clash with ours.
+                  The RabbitMQ client's internal references are rewritten automatically.
+                -->
+                <relocation>
+                  <pattern>io.netty</pattern>
+                  <shadedPattern>com.rabbitmq.marchhare.shaded.netty</shadedPattern>
+                </relocation>
+              </relocations>
+
+              <transformers>
+                <!-- Merge META-INF/services/* entries from all shaded JARs -->
+                <transformer implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer"/>
+                <transformer implementation="org.apache.maven.plugins.shade.resource.ApacheLicenseResourceTransformer"/>
+                <transformer implementation="org.apache.maven.plugins.shade.resource.ApacheNoticeResourceTransformer"/>
+              </transformers>
+
+              <filters>
+                <!--
+                  SLF4J API is kept as a separate JAR (lib/ext/slf4j-api.jar) so that
+                  the RabbitMQ client's log output flows through whatever SLF4J backend
+                  the user's application configures.  Including it in the shaded JAR
+                  would isolate logging and prevent users from routing it to Logback, etc.
+                -->
+                <filter>
+                  <artifact>org.slf4j:*</artifact>
+                  <excludes>
+                    <exclude>**</exclude>
+                  </excludes>
+                </filter>
+
+                <!-- Strip JAR signatures, per-artifact manifests, and Maven metadata -->
+                <filter>
+                  <artifact>*:*</artifact>
+                  <excludes>
+                    <exclude>META-INF/MANIFEST.MF</exclude>
+                    <exclude>META-INF/maven/**</exclude>
+                    <exclude>META-INF/*.SF</exclude>
+                    <exclude>META-INF/*.DSA</exclude>
+                    <exclude>META-INF/*.RSA</exclude>
+                  </excludes>
+                </filter>
+              </filters>
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
+    </plugins>
+  </build>
+</project>