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

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

1 101 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.