Configuring a Jetty Servlet Proxy

Sample application can be downloaded from here

Lets say you deploy app1, app2, someotherapp to devhost:3000 and testhost:3000 then those apps can be accessed as follows

DEV instances
http://devhost:3000/app1
http://devhost:3000/app2
http://devhost:3000/someotherapp

TEST instances
http://testhost:3000/app1
http://testhost:3000/app2
http://testhost:3000/someotherapp

Many a times one application depends upon other applications with in the same server and hence, your application may contain code snippets as follows:

<link title="Stylesheet" href="/someotherapp/style.css" rel="stylesheet" media="screen" type="text/css" />

Further, those can be directly accessed as well

http://devhost:3000/someotherapp/style.css
http://testhost:3000/someotherapp/style.css

Further Jetty is the best choice for local development either embedded or using jetty-maven-plugin.

In this case it does not make sense to replicate the entire environment locally, instead those urls can be proxied in local environment such that /someotherapp/style.css would be proxied to http://devhost:3000/someotherapp/style.css

Here is how you can achieve it.

1) Map ProxyServlet.Transparent to /someotherapp/*
2) Set the Servlet init parameters as follows
ProxyTo ==> http://devhost:3000/someotherapp
Prefix ==> /someotherapp

The Above Two Steps Can be Done in Two Ways

Configuring Using Java

package com.nadeem.app;

import java.lang.management.ManagementFactory;

import javax.management.MBeanServer;

import org.apache.wicket.util.time.Duration;
import org.eclipse.jetty.jmx.MBeanContainer;
import org.eclipse.jetty.server.Handler;
import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.server.bio.SocketConnector;
import org.eclipse.jetty.server.handler.DefaultHandler;
import org.eclipse.jetty.server.handler.HandlerList;
import org.eclipse.jetty.server.ssl.SslSocketConnector;
import org.eclipse.jetty.servlet.ServletContextHandler;
import org.eclipse.jetty.servlet.ServletHandler;
import org.eclipse.jetty.servlet.ServletHolder;
import org.eclipse.jetty.util.resource.Resource;
import org.eclipse.jetty.util.ssl.SslContextFactory;
import org.eclipse.jetty.webapp.WebAppContext;

public class Start {

    public static void main(String[] args) throws Exception {
        int timeout = (int) Duration.ONE_HOUR.getMilliseconds();

        SocketConnector connector = newConnector(timeout);
        Server server = newServer(timeout, connector);

        addSecureSupport(timeout, connector, server);

        addJmxSupport(server);

        try {
            System.out.println(">>> STARTING EMBEDDED JETTY SERVER, PRESS ANY KEY TO STOP");
            server.start();
            System.in.read();
            System.out.println(">>> STOPPING EMBEDDED JETTY SERVER");
            server.stop();
            server.join();
        } catch (Exception e) {
            e.printStackTrace();
            System.exit(1);
        }
    }

    private static void addJmxSupport(Server server) throws Exception
    {
        // START JMX SERVER
        MBeanServer mBeanServer = ManagementFactory.getPlatformMBeanServer();
        MBeanContainer mBeanContainer = new MBeanContainer(mBeanServer);
        server.getContainer().addEventListener(mBeanContainer);
        mBeanContainer.start();
    }

    private static void addSecureSupport(int timeout, SocketConnector connector, Server server)
    {
        Resource keystore = Resource.newClassPathResource("/keystore");
        if (keystore != null && keystore.exists()) {
            // if a keystore for a SSL certificate is available, start a SSL
            // connector on port 8443.
            // By default, the quickstart comes with a Apache Wicket Quickstart
            // Certificate that expires about half way september 2021. Do not
            // use this certificate anywhere important as the passwords are
            // available in the source.

            connector.setConfidentialPort(8443);

            SslContextFactory factory = new SslContextFactory();
            factory.setKeyStoreResource(keystore);
            factory.setKeyStorePassword("wicket");
            factory.setTrustStoreResource(keystore);
            factory.setKeyManagerPassword("wicket");
            SslSocketConnector sslConnector = new SslSocketConnector(factory);
            sslConnector.setMaxIdleTime(timeout);
            sslConnector.setPort(8443);
            sslConnector.setAcceptors(4);
            server.addConnector(sslConnector);

            System.out.println("SSL access to the quickstart has been enabled on port 8443");
            System.out.println("You can access the application using SSL on https://localhost:8443");
            System.out.println();
        }
    }

    private static Server newServer(int timeout, SocketConnector connector) {
        Server server = new Server(); 
        server.setHandler(newHandlers(server));
        server.addConnector(connector);
        return server;
    }

    private static HandlerList newHandlers(Server server) {
        WebAppContext appContext = newWebAppContext(server);

        HandlerList handlers = new HandlerList();
        handlers.setHandlers(new Handler[] {appContext, proxyHandler(), new DefaultHandler()});
        return handlers;
    }

    private static SocketConnector newConnector(int timeout) {
        SocketConnector connector = new SocketConnector();

        // Set some timeout options to make debugging easier.
        connector.setMaxIdleTime(timeout);
        connector.setSoLingerTime(-1);
        connector.setPort(8080);

        return connector;

    }

    private static WebAppContext newWebAppContext(Server server) {
        WebAppContext bb = new WebAppContext();
        bb.setServer(server);
        bb.setContextPath("/webApp");
        bb.setWar("src/main/webapp");
        return bb;
    }

    private static ServletContextHandler proxyHandler() {
        ServletContextHandler contextHandler = new ServletContextHandler();
        contextHandler.setServletHandler(newServletHandler());

        return contextHandler;
    }

    private static ServletHandler newServletHandler() {


        ServletHandler handler = new ServletHandler();

        ServletHolder holder = handler.addServletWithMapping(org.eclipse.jetty.servlets.ProxyServlet.Transparent.class, "/proxy/*");
        holder.setInitParameter("ProxyTo", "http://localhost:8080/webApp");
        holder.setInitParameter("Prefix", "/proxy");        

        return handler;
    }
}

Configuring Using Maven Jetty Plugin

<plugin>
    <groupId>org.mortbay.jetty</groupId>
    <artifactId>jetty-maven-plugin</artifactId>
    <version>${jetty.version}</version>
    <configuration>
        <webAppConfig>
            <contextPath>/webApp</contextPath>
        </webAppConfig>
        <jettyConfig>src/main/etc/jetty.xml</jettyConfig>
        <connectors>
            <connector implementation="org.eclipse.jetty.server.nio.SelectChannelConnector">
                <port>8080</port>
                <maxIdleTime>3600000</maxIdleTime>
            </connector>                      
        </connectors>
    </configuration>
    <dependencies>
        <dependency>
            <groupId>org.eclipse.jetty.aggregate</groupId>
            <artifactId>jetty-all-server</artifactId>
            <version>${jetty.version}</version>
        </dependency>
    </dependencies>
</plugin>

src/main/etc/jetty.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE Configure PUBLIC "-//Jetty//Configure//EN" "http://www.eclipse.org/jetty/configure_9_0.dtd">

<Configure id="server" class="org.eclipse.jetty.server.Server">

<New id="ServletContextHandler" class="org.eclipse.jetty.servlet.ServletContextHandler">
 <Set name="servletHandler">
<New id="servletHandler" class="org.eclipse.jetty.servlet.ServletHandler">
<Call id="proxyHolder" name="addServletWithMapping">
<Arg>org.eclipse.jetty.servlets.ProxyServlet$Transparent</Arg>
<Arg>/proxy/*</Arg>
<Call name="setInitParameter">
<Arg>maxThreads</Arg>
<Arg>
<Property name="jetty.proxy.maxThreads" default="128" />
</Arg>
</Call>
<Call name="setInitParameter">
<Arg>maxConnections</Arg>
<Arg>
<Property name="jetty.proxy.maxConnections" default="256" />
</Arg>
</Call>
<Call name="setInitParameter">
<Arg>idleTimeout</Arg>
<Arg>
<Property name="jetty.proxy.idleTimeout" default="30000" />
</Arg>
</Call>
<Call name="setInitParameter">
<Arg>timeout</Arg>
<Arg>
<Property name="jetty.proxy.timeout" default="60000" />
</Arg>
</Call>
<Call name="setInitParameter">
<Arg>ProxyTo</Arg>
<Arg>http://localhost:8080/wicket</Arg>
</Call>
<Call name="setInitParameter">
<Arg>Prefix</Arg>
<Arg>/proxy</Arg>
</Call>
</Call>

</New>
</Set>
</New>

<Set name="handler">
<New class="org.eclipse.jetty.server.handler.HandlerList">
<Set name="handlers">
<Array type="org.eclipse.jetty.server.Handler">
<Item>
<Ref id="ServletContextHandler"></Ref>
</Item>
</Array>
</Set>
</New>
</Set>


</Configure>