Run java web apps in embedded containers with Maven, Jetty and Tomcat

Adrian MateiJune 26th, 2015Last Updated: June 26th, 2015

1 90 2 minutes read

While developing java web applications is very practical to have quick feedback from a “real” environment. In this post I’ll explore how to run a java web application with Maven in an embedded container be it Jetty or Tomcat. I’ll show how I have configured them for the development of podcastpedia project backing the Podcastpedia.org website.

Prerequisites

You should have Maven and at least Java 7 installed. Ideally you could setup up the podcastpedia project yourself to see it in action.

Jetty Maven Plugin

Plugin Configuration

<!-- http://www.eclipse.org/jetty/documentation/current/jetty-maven-plugin.html -->
<plugin>
	<groupId>org.eclipse.jetty</groupId>
	<artifactId>jetty-maven-plugin</artifactId>
	<version>${jetty.version}</version>
	<configuration>
		<jettyConfig>${project.basedir}/src/main/resources/config/jetty9.xml</jettyConfig>
		<stopKey>STOP</stopKey>
		<stopPort>9999</stopPort>
		<scanIntervalSeconds>5</scanIntervalSeconds>
		<scanTargets>
			<scanTarget>${project.basedir}/src/main</scanTarget>
			<scanTarget>${project.basedir}/src/test</scanTarget>
		</scanTargets>
		<contextXml>${project.basedir}/src/test/resources/jetty-context.xml</contextXml>
		<webAppConfig>
			<contextPath>/</contextPath>
		</webAppConfig>
	</configuration>
	<dependencies>
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<version>${mysql.connector.java.version}</version>
		</dependency>
		<dependency>
			<groupId>javax.mail</groupId>
			<artifactId>mail</artifactId>
			<version>${java.mail.version}</version>
		</dependency>
		<dependency>
			<groupId>org.apache.tomcat</groupId>
			<artifactId>tomcat-jdbc</artifactId>
			<version>${tomcat.jdbc.version}</version>
		</dependency>
	</dependencies>
</plugin>

Notes:

jettyConfig points to the Jetty configuration file; see next section for more explanations
defined folders (scanTargets) where Jetty looks for changes every 5 seconds (scanInterval)
defined external dependencies to connect to database and send email

Jetty.xml configuration file

Jetty xml configuration file

<?xml version="1.0" encoding="UTF-8"?>
<Configure class="org.eclipse.jetty.webapp.WebAppContext">
	<New id="pcmdbDS" class="org.eclipse.jetty.plus.jndi.Resource">
		<Arg>jdbc/pcmDB</Arg>
		<Arg>
			<New class="com.mysql.jdbc.jdbc2.optional.MysqlConnectionPoolDataSource">
				<Set name="Url">jdbc:mysql://localhost:3307/pcmDB?allowMultiQueries=true
				</Set>
				<Set name="User">pcm</Set>
				<Set name="Password">pcm_pw</Set>
			</New>
		</Arg>
	</New>
	<New id="mailSessionId" class="org.eclipse.jetty.plus.jndi.Resource">
		<Arg>mail/Session</Arg>
		<Arg>
			<New class="org.eclipse.jetty.jndi.factories.MailSessionReference">
				<Set name="user">test-dev@podcastpedia.org</Set>
				<Set name="password">test-dev</Set>
				<Set name="properties">
					<New class="java.util.Properties">
						<Put name="mail.host">mail.podcastpedia.org</Put>
						<Put name="mail.debug">true</Put>
						<Put name="mail.transport.protocol">smtp</Put>
						<Put name="mail.smtp.port">25</Put>
						<Put name="mail.smtp.auth">true</Put>
					</New>
				</Set>
			</New>
		</Arg>
	</New>
</Configure>

In the Jetty configuration file (jetty.xml) you have the following configured:

The Server class (or subclass if extended) and global options.
A ThreadPool (min and max thread).
Connectors (ports, timeouts, buffer sizes, protocol).
The handler structure (default handlers and/or a contextHandlerCollections).
The deployment manager that scans for and deploys webapps and contexts.
Login services that provide authentication checking.
A request log.

Apache Tomcat Maven Plugin

Apache Tomcat Maven Plugin Configuration

<!-- https://tomcat.apache.org/maven-plugin-trunk/index.html -->
<plugin>
	<groupId>org.apache.tomcat.maven</groupId>
	<artifactId>tomcat7-maven-plugin</artifactId>
	<version>2.2</version>
	<configuration>
		<!-- http port -->
		<port>8080</port>
		<!-- application path always starts with /-->
		<path>/</path>
		<!-- optional path to a context file -->
		<contextFile>context.xml</contextFile>
		<!-- optional system propoerties you want to add -->
		<systemProperties>
			<appserver.base>${project.build.directory}/appserver-base</appserver.base>
			<appserver.home>${project.build.directory}/appserver-home</appserver.home>
			<derby.system.home>${project.build.directory}/appserver-base/logs</derby.system.home>
			<java.io.tmpdir>${project.build.directory}</java.io.tmpdir>
		</systemProperties>
		<!-- if you want to use test dependencies rather than only runtime -->
		<useTestClasspath>false</useTestClasspath>
		<!-- optional if you want to add some extra directories into the classloader -->
		<additionalClasspathDirs>
			<additionalClasspathDir></additionalClasspathDir>
		</additionalClasspathDirs>
	</configuration>
	<!-- For any extra dependencies needed when running embedded Tomcat (not WAR dependencies) add them below -->
	<dependencies>
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<version>${mysql.connector.java.version}</version>
		</dependency>
		<dependency>
			<groupId>javax.mail</groupId>
			<artifactId>mail</artifactId>
			<version>${java.mail.version}</version>
		</dependency>
		<dependency>
			<groupId>org.apache.tomcat</groupId>
			<artifactId>tomcat-jdbc</artifactId>
			<version>${tomcat.jdbc.version}</version>
		</dependency>
	</dependencies>
</plugin>

Notes

specify port where Tomcat runs
specify contextFile where Tomcat looks for configuration
defined external dependencies to connect to database and send email

Context.xml

<Context>
  <Resource
            name="jdbc/pcmDB"
            auth="Container"
            type="javax.sql.DataSource"
            factory="org.apache.tomcat.jdbc.pool.DataSourceFactory"
            initialSize="5"
            maxActive="55"
            maxIdle="21"
            minIdle="13"
            timeBetweenEvictionRunsMillis="34000"
            minEvictableIdleTimeMillis="55000"
            validationQuery="SELECT 1"
            validationInterval="34"
            testOnBorrow="true"
            removeAbandoned="true"
            removeAbandonedTimeout="233"
            username="pcm"
            password="pcm_pw"
            driverClassName="com.mysql.jdbc.Driver"
            url="jdbc:mysql://localhost:3307/pcmDB?allowMultiQueries=true"
   /> 

	<Resource name="mail/Session" auth="Container"
	            type="javax.mail.Session"
		        username="test-dev@podcastpedia.org"
		        password="test-dev"	            
	            mail.smtp.host="mail.podcastpedia.org"
	            mail.smtp.port="25"
	            mail.smtp.user="test-dev@podcastpedia.org"
	            mail.transport.protocol="smtp" 
	            mail.smtp.auth="true"
	/> 
</Context>

In context.xml there are defined the database and email resources.

There you go… Java webapps powered by Spring Framework running light servlet containers posing a true alternative to JAVA EE servers and all the costs that come with them.

Note:
These are simple configurations, but suffice for current development. My advice is to read the corresponding documentation for more advanced options and capabilities.