Adding custom handler to jetty throws ClassNotFoundException

Question

I am trying to inject a custom handler to jetty.

I have written the handler in my application code which is packaged as a war.

package com.foo.bar

import javax.servlet.http.{HttpServletRequest, HttpServletResponse}
import org.eclipse.jetty.server.Request
import org.eclipse.jetty.server.handler.AbstractHandler

// scalastyle:off println
class CustomJettyHandler extends AbstractHandler {
  override def handle(target: String, baseRequest: Request,
                      request: HttpServletRequest, response: HttpServletResponse): Unit = {

    println("This is a custom jetty handler")
  }
}
// scalastyle:on println

I have then injected this handler in the jetty.xml file:

<?xml version="1.0"?>
<!DOCTYPE Configure PUBLIC "-//Jetty//Configure//EN" "http://www.eclipse.org/jetty/configure_9_3.dtd">
<Configure id="Server" class="org.eclipse.jetty.server.Server">
........
........
<Call name="insertHandler">
    <Arg>
      <New id="CustomJettyHandler" class="com.foo.bar.CustomJettyHandler"/>
    </Arg>
</Call>
........

I am now running jetty in standalone mode. Note that I am passing the location where CustomJettyHandler.class resides to jetty-start.jar.

java -server -Dorg.eclipse.jetty.util.log.class=org.eclipse.jetty.util.log.StdErrLog -jar lib/jetty-start.jar OPTIONS=All --lib=lib/* --lib=webapps/root/WEB-INF/classes/com/foo/bar/* etc/jetty.xml etc/jetty-jmx.xml --debug

In my application logs, I can see jetty loading my custom handler to its classpath but then eventually failing because of ClassNotFoundException. Can someone point out where could this be going wrong?

.......
rawlibref = webapps/root/WEB-INF/classes/com/foo/bar/*
expanded = webapps/root/WEB-INF/classes/com/foo/bar/*
getPaths('webapps/root/WEB-INF/classes/com/foo/bar/*')
Using relative path pattern: glob:**/webapps/root/WEB-INF/classes/com/foo/bar/*
Found [webapps/root/WEB-INF/classes/com/foo/bar/CustomJettyHandler.class]  /Users/...path_to_application.../webapps/root/WEB-INF/classes/com/foo/bar/CustomJettyHandler.class
Adding classpath component: /Users/...path_to_application.../webapps/root/WEB-INF/classes/com/foo/bar/CustomJettyHandler.class
.......
.......
.......
URLClassLoader.url[33] = file:/Users/...path_to_application.../webapps/root/WEB-INF/classes/com/foo/bar/CustomJettyHandler.class
Loaded 34 URLs into URLClassLoader
class org.eclipse.jetty.xml.XmlConfiguration - 9.4.24.v20191120
Command Line Args: /var/folders/z5/dmt38gq54kxcrrzpgvbl5m_c0000gp/T/start_6046998329479549547.properties /Users/...path_to_application.../etc/jetty.xml /Users/...path_to_application.../etc/jetty-jmx.xml
2020-05-27 14:46:13.676:INFO::main: Logging initialized @477ms to org.eclipse.jetty.util.log.StdErrLog
2020-05-27 14:46:13.934:INFO:oeju.TypeUtil:main: JVM Runtime does not support Modules
2020-05-27 14:46:14.007:WARN:oejx.XmlConfiguration:main: Config error at <Call name="insertHandler"><Arg>|      <New id="CustomJettyHandler" class="com.foo.bar.CustomJettyHandler"/>|    </Arg></Call> java.lang.ClassNotFoundException: com.foo.bar.CustomJettyHandler in file:///Users/...path_to_application.../etc/jetty.xml
2020-05-27 14:46:14.007:WARN:oejx.XmlConfiguration:main:
java.security.PrivilegedActionException: java.lang.ClassNotFoundException: com.foo.bar.CustomJettyHandler
    at java.security.AccessController.doPrivileged(Native Method)
    at org.eclipse.jetty.xml.XmlConfiguration.main(XmlConfiguration.java:1837)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.eclipse.jetty.start.Main.invokeMain(Main.java:218)
    at org.eclipse.jetty.start.Main.start(Main.java:491)
    at org.eclipse.jetty.start.Main.main(Main.java:77)
Caused by:
java.lang.ClassNotFoundException: com.foo.bar.CustomJettyHandler
    at java.net.URLClassLoader.findClass(URLClassLoader.java:382)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    at org.eclipse.jetty.util.Loader.loadClass(Loader.java:64)
    at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.newObj(XmlConfiguration.java:1028)
    at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.itemValue(XmlConfiguration.java:1638)
    at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.value(XmlConfiguration.java:1539)
    at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.access$500(XmlConfiguration.java:369)
    at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration$AttrOrElementNode.getList(XmlConfiguration.java:1768)
    at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration$AttrOrElementNode.getList(XmlConfiguration.java:1744)
    at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.call(XmlConfiguration.java:919)
    at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.configure(XmlConfiguration.java:512)
    at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.configure(XmlConfiguration.java:454)
    at org.eclipse.jetty.xml.XmlConfiguration.configure(XmlConfiguration.java:354)
    at org.eclipse.jetty.xml.XmlConfiguration.lambda$main$0(XmlConfiguration.java:1874)
    at java.security.AccessController.doPrivileged(Native Method)
    at org.eclipse.jetty.xml.XmlConfiguration.main(XmlConfiguration.java:1837)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.eclipse.jetty.start.Main.invokeMain(Main.java:218)
    at org.eclipse.jetty.start.Main.start(Main.java:491)
    at org.eclipse.jetty.start.Main.main(Main.java:77)

score 1 · Answer 1 · answered May 27 '20 at 22:57

Where did you get this command line from?

java -server \
  -Dorg.eclipse.jetty.util.log.class=org.eclipse.jetty.util.log.StdErrLog\
  -jar lib/jetty-start.jar\
  OPTIONS=All \
  --lib=lib/* \
  --lib=webapps/root/WEB-INF/classes/com/foo/bar/* \
  etc/jetty.xml \
  etc/jetty-jmx.xml \
  --debug

That's not valid for use with Jetty 9.x's start.jar

Some advice

don't use XML directly on the java command line, that's the responsibility of the start.jar and the jetty-home module system (order is SUPER IMPORTANT).
Your choices of etc/jetty.xml and etc/jetty-jmx.xml is an incomplete list of xmls. (you are missing all dependent XML files)
don't edit the standard Jetty XML files, leave them be, otherwise you'll complicate upgrades later. Use XML to inject your behavior instead (see below for example)
OPTIONS is not supported by Jetty 9.x (that's old school Codehaus / Jetty 6 behavior)
Your usage of --lib= is discouraged, it only supports fully qualified paths to jars or directories with exploded class trees (not relative paths, no globs supported).
-Dorg.eclipse.jetty.util.log.class=org.eclipse.jetty.util.log.StdErrLog is a harsh way of setting up logging. Create a jetty-logging.properties files and make sure it's present on the classpath.

Example contents of jetty-logging.properties

org.eclipse.jetty.util.log.class=org.eclipse.jetty.util.log.StdErrLog
org.eclipse.jetty.LEVEL=INFO
#org.eclipse.jetty.deploy.LEVEL=DEBUG

Do this instead.

Create an injection based XML for your new handler.

my-handler.xml

<?xml version="1.0"?>
<!DOCTYPE Configure PUBLIC "-//Jetty//Configure//EN" "http://www.eclipse.org/jetty/configure_9_3.dtd">

<Configure id="Server" class="org.eclipse.jetty.server.Server">
    <Call name="insertHandler">
        <Arg>
            <New id="CustomJettyHandler" class="com.foo.bar.CustomJettyHandler" />
        </Arg>
    </Call>
</Configure>

Next create your jetty-base directory properly (for jetty's start.jar)

# Create your "jetty-base" directory
$ mkdir /path/to/myjettybase
$ cd /path/to/myjettybase

# Establish the basic files / directories / modules that you want to use
# You can find the configuration in start.ini or start.d/*.ini
$ java -jar /path/to/jetty-home/start.jar --add-to-start=http,jmx,deploy,ext,resources

# Copy your custom handler JAR into place
$ cp /path/to/my-handlers.jar /path/to/myjettybase/lib/ext/
# Copy your custom handler XML into place
$ cp /path/to/my-handler.xml /path/to/myjettybase/etc/
# Ensure that the custom handler XML is loaded into the jetty instance at the right point in the XML load order by declaring it to be used in a custom INI
$ mkdir start.d
$ echo "etc/my-handler.xml" >> start.d/my-handlers.ini

# Copy your jetty-logging.properties into place
$ cp /path/to/my-jetty-logging.properties /path/to/myjettybase/resources/jetty-logging.properties

# verify that your configuration looks sane (including the server classpath)
$ cd /path/to/myjettybase
$ java -jar /path/to/jetty-home/start.jar --list-config

# run your instance
$ cd /path/to/myjettybase
$ java -jar /path/to/jetty-home/start.jar

But that's not all, seeing as you seem to want to use jetty-home from a maven-style project (or project layout), you can do that too!

An example project showing this can be found at ...

https://github.com/jetty-project/servlet-error-page-handling

That maven project is also a valid jetty-base directory suitable for execution by a jetty-home archive somewhere else on your machine.

I copied `myHandler` related files in my jetty-home directory and the `demo.war` file to `/jetty-home/webapps` directory. I can see my-handler in `--list-config`: ` 1: 1.0-SNAPSHOT | ${jetty.base}/lib/ext/jetty-custom-handler-1.0-SNAPSHOT.jar Jetty Active XMLs: ${jetty.base}/etc/my-handler.xml` But running the server from jetty home gives `java.lang.IllegalStateException: No Method: | | on class org.eclipse.jetty.server.Server` — Arpit Jain, May 28 '20 at 08:27
I even tried doing this from `jetty-base` and that also results in: `java.lang.IllegalStateException: No Method: on class org.eclipse.jetty.server.Server Caused by: java.lang.NoSuchMethodException: insertHandler at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.call(XmlConfiguration.java:1008) at org.eclipse.jetty.xml.XmlConfiguration$JettyXmlConfiguration.call(XmlConfiguration.java:963)` — Arpit Jain, May 28 '20 at 08:42
"handler in my application code which is packaged as a war" is your handler IN the WAR file, or on the Server classpath? — Joakim Erdfelt, May 28 '20 at 15:07
There are two ways I have tried this: 1. Writing the handler class in a module which is packaged as a war, and then passing the `target/classes` directory of this module to jetty using `--lib` parameter. 2. Writing the handler class in a module which is packaged as a jar, and then copying the jar in `/lib/ext/ directory within `jetty-base` directory. Both the cases show correct config but throw exceptions on jetty startup. Here's a GitHub repo which reproduces both these issues. I have also added the error details in README. https://github.com/calvincodes/custom-handler-jetty — Arpit Jain, May 28 '20 at 18:56
Were you able to reproduce the error using the repository which I have mentioned in the previous comment? https://github.com/calvincodes/custom-handler-jetty @joakim-erdfelt — Arpit Jain, Jun 08 '20 at 18:25

Adding custom handler to jetty throws ClassNotFoundException

1 Answers1

Do this instead.