Adding custom handler to jetty throws ClassNotFoundException - scala

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)

Answer 1

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.