HDDS-14005. EventNotification: EventNotification: add the plugin framework by gardenia · Pull Request #10095 · apache/ozone

gardenia · 2026-04-20T16:58:52Z

Please describe your PR in detail:

Add the plugin framework for dynamically configurable EventListener plugin
an event listener plugin will implement the interface OMEventListener
plugins can be loaded/configured dynamically similarly to ranger plugins, e.g.:

ozone.om.plugin.destination.kafka=true
ozone.om.plugin.destination.kafka.classname=org.apache.hadoop.ozone.om.eventlistener.OMEventListenerKafkaPublisher
ozone.notify.kafka.topic=test123
ozone.notify.kafka.bootstrap.servers=kafka-3:29092,kafka-1:29092,kafka-2:29092

NOTE: this change does not provide any concrete plugin implementation

What is the link to the Apache JIRA

https://issues.apache.org/jira/browse/HDDS-14005

How was this patch tested?

unit tests

…gurable EventListener plugins

gardenia · 2026-04-20T17:02:01Z

@ChenSammi : as per #9366 I was unable to reopen that PR and so the only option was to open a new one.

Copilot

Pull request overview

Adds a basic plugin framework for OM Event Listener integrations, enabling dynamically configurable OMEventListener implementations to be discovered via OzoneConfiguration and lifecycle-managed by OM.

Changes:

Introduces the OMEventListener and OMEventListenerPluginContext APIs in hadoop-ozone/common.
Adds OMEventListenerPluginManager (load/start/shutdown) and a minimal context implementation in ozone-manager.
Adds unit tests and dummy listener implementations to validate plugin loading behavior.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
hadoop-ozone/ozone-manager/src/main/java/org/apache/hadoop/ozone/om/eventlistener/OMEventListenerPluginManager.java	Implements config-based discovery, instantiation, and lifecycle management for `OMEventListener` plugins.
hadoop-ozone/ozone-manager/src/main/java/org/apache/hadoop/ozone/om/eventlistener/OMEventListenerPluginContextImpl.java	Provides an OM-specific context object passed to plugins.
hadoop-ozone/ozone-manager/src/main/java/org/apache/hadoop/ozone/om/eventlistener/package-info.java	Package documentation for the OM-side eventlistener implementation.
hadoop-ozone/common/src/main/java/org/apache/hadoop/ozone/om/eventlistener/OMEventListener.java	Defines the plugin interface (initialize/start/shutdown).
hadoop-ozone/common/src/main/java/org/apache/hadoop/ozone/om/eventlistener/OMEventListenerPluginContext.java	Defines the (currently empty) plugin context interface.
hadoop-ozone/common/src/main/java/org/apache/hadoop/ozone/om/eventlistener/package-info.java	Package documentation for the common eventlistener API.
hadoop-ozone/ozone-manager/src/test/java/org/apache/hadoop/ozone/om/eventlistener/TestOMEventListenerPluginManager.java	Adds unit tests for plugin discovery/loading error handling.
hadoop-ozone/ozone-manager/src/test/java/org/apache/hadoop/ozone/om/eventlistener/FooPlugin.java	Dummy test plugin implementing `OMEventListener`.
hadoop-ozone/ozone-manager/src/test/java/org/apache/hadoop/ozone/om/eventlistener/BarPlugin.java	Dummy test plugin implementing `OMEventListener`.

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Copilot · 2026-04-22T02:09:32Z

+  @Test
+  public void testLoadSinglePlugin() throws InterruptedException {
+    OzoneConfiguration conf = new OzoneConfiguration();
+    conf.set("ozone.om.plugin.destination.foo", "enabled");


These tests declare throws InterruptedException, but nothing in the test body blocks or interrupts. Removing the unused checked exception would simplify the test signatures.

Copilot · 2026-04-22T02:09:32Z

+  static List<OMEventListener> loadAll(OzoneManager ozoneManager, OzoneConfiguration conf) {
+    List<OMEventListener> plugins = new ArrayList<>();
+
+    Map<String, String> props = conf.getPropsMatchPrefixAndTrimPrefix(PLUGIN_DEST_BASE);
+    List<String> destNameList = new ArrayList<>();


getPropsMatchPrefixAndTrimPrefix is called with PLUGIN_DEST_BASE without a trailing dot, which means the trimmed keys will start with a leading . (eg .foo) and the match can also include unintended keys like ozone.om.plugin.destinationX.... This makes later concatenation (PLUGIN_DEST_BASE + destName + ".classname") fragile. Consider using a prefix with the delimiter (eg PLUGIN_DEST_BASE + ".") and keeping destName normalized (no leading dot).

Copilot · 2026-04-22T02:09:32Z

+        OMEventListener impl = cls.newInstance();
+        impl.initialize(conf, pluginContext);
+
+        plugins.add(impl);
+      } catch (Exception ex) {


Class#newInstance() is deprecated and can fail for classes without a public no-arg constructor; it also provides less useful exception context. Prefer cls.getDeclaredConstructor().newInstance() and catch ReflectiveOperationException (or the specific exceptions) so failures are logged with clear cause.

Suggested change

OMEventListener impl = cls.newInstance();

impl.initialize(conf, pluginContext);

plugins.add(impl);

} catch (Exception ex) {

OMEventListener impl = cls.getDeclaredConstructor().newInstance();

impl.initialize(conf, pluginContext);

plugins.add(impl);

} catch (ReflectiveOperationException ex) {

Copilot · 2026-04-22T02:09:33Z

+
+  public void startAll() {
+    for (OMEventListener plugin : plugins) {
+      plugin.start();


If any plugin throws from start(), this will abort starting subsequent plugins. Consider wrapping each plugin.start() in its own try/catch so one bad plugin doesn't prevent others from starting, and log the plugin class/name on failure.

Suggested change

plugin.start();

try {

plugin.start();

} catch (Exception ex) {

LOG.error("Failed to start event listener plugin {}",

plugin.getClass().getName(), ex);

}

Copilot · 2026-04-22T02:09:33Z

+
+  public void shutdownAll() {
+    for (OMEventListener plugin : plugins) {
+      plugin.shutdown();


If any plugin throws from shutdown(), this will abort shutting down subsequent plugins. Consider handling exceptions per plugin and continuing shutdown so a single failure doesn't block cleanup of the rest.

Suggested change

plugin.shutdown();

try {

plugin.shutdown();

} catch (Exception ex) {

LOG.error("Failed to shut down event listener plugin {}", plugin, ex);

}

Copilot · 2026-04-22T02:09:33Z

+  private static Class<? extends OMEventListener> resolvePluginClass(OzoneConfiguration conf,
+                                                                     String destName) {
+    String classnameProp = PLUGIN_DEST_BASE + destName + ".classname";
+    LOG.info("Gettting classname for {} with propety {}", destName, classnameProp);


Typo in the log message: "Gettting" / "propety". Fixing this will make logs easier to search/understand.

Suggested change

LOG.info("Gettting classname for {} with propety {}", destName, classnameProp);

LOG.info("Getting classname for {} with property {}", destName, classnameProp);

Copilot · 2026-04-22T02:09:33Z

+  public void testPluginClassDoesNotImplementInterface() throws InterruptedException {
+    OzoneConfiguration conf = new OzoneConfiguration();
+    conf.set("ozone.om.plugin.destination.foo", "enabled");
+    conf.set("ozone.om.plugin.destination.foo.classname", "org.apache.hadoop.ozone.om.eventlistener.BrokenFooPlugin");


testPluginClassDoesNotImplementInterface configures classname org.apache.hadoop.ozone.om.eventlistener.BrokenFooPlugin, but BrokenFooPlugin is declared as a private static nested class in this test, so its runtime name is TestOMEventListenerPluginManager$BrokenFooPlugin. As written, this test is effectively exercising the "class does not exist" path rather than the "does not implement interface" path. Consider using BrokenFooPlugin.class.getName() or moving BrokenFooPlugin to its own top-level test class in the same package.

Suggested change

conf.set("ozone.om.plugin.destination.foo.classname", "org.apache.hadoop.ozone.om.eventlistener.BrokenFooPlugin");

conf.set("ozone.om.plugin.destination.foo.classname", BrokenFooPlugin.class.getName());

HDDS-14005. EventNotification: Added the concept of dynamically confi…

b698ce0

…gurable EventListener plugins

gardenia mentioned this pull request Apr 21, 2026

HDDS-14005. EventNotification: add the plugin framework #9365

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ChenSammi requested a review from Copilot April 22, 2026 02:05

Copilot started reviewing on behalf of ChenSammi April 22, 2026 02:05 View session

Copilot AI reviewed Apr 22, 2026

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HDDS-14005. EventNotification: EventNotification: add the plugin framework#10095

HDDS-14005. EventNotification: EventNotification: add the plugin framework#10095
gardenia wants to merge 2 commits intoapache:HDDS-13513_Event_Notification_FeatureBranchfrom
gardenia:HDDS-14005

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	LOG.info("Gettting classname for {} with propety {}", destName, classnameProp);
	LOG.info("Getting classname for {} with property {}", destName, classnameProp);

	conf.set("ozone.om.plugin.destination.foo.classname", "org.apache.hadoop.ozone.om.eventlistener.BrokenFooPlugin");
	conf.set("ozone.om.plugin.destination.foo.classname", BrokenFooPlugin.class.getName());

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gardenia commented Apr 20, 2026

What is the link to the Apache JIRA

How was this patch tested?

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