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Deploying WebApps

Using Location-Based Deployment
Deploying Contexts (Descriptor Based)

You can make Jetty aware of web applications to deploy in two ways:

In either case the web application may be either packed or unpacked WAR files.

Before discussing the mechanisms for deploying Jetty applications, it is helpful to define two terms:

Using Location-Based Deployment

In a default installation, Jetty scans its $JETTY_HOME/webapps directory at startup for web applications to deploy. To deploy your web application, simply place it in that directory.

Once it detects the web application, Jetty deploys it in the following manner:

  • It deploys the file foo.war as a webapp at context /foo.

  • It deploys the directory foo/ at context /foo. If the directory has a WEB-INF subdirectory, Jetty treats it as a servlet webapp, otherwise Jetty serves it only as static content.

  • If both a foo.war and a foo/ directory exist, Jetty uses the one with the most recent last-modified date.

  • If the webapp is called root.war or the directory is called root/, Jetty deploys it at the / context.

  • If the contextXmlDir option is used and a foo.xml file exists in that directory, the WebAppProvider defers to the ContextProvider for actual webapp deployment.

Deploying Contexts (Descriptor Based)

Using the location based deployment model is quick and easy, but sometimes you might need to tune certain deployment properties (for example, you want to deploy with a context path that is not based on the file name, or you want to define a special database connection pool just for this web application). You can use a context deployment descriptor file to accomplish such tuning.

Using Basic Descriptor Files

In a default Jetty installation, Jetty scans its $JETTY_HOME/contexts directory for context deployment descriptor files. To deploy a web application using such a file, simply place the file in that directory.

The deployment descriptor file itself is a standard Jetty [[Jetty/Reference/jetty.xml syntax|configuration]] //TODO Xref// file that configures a WebAppContext class. For a basic installation you probably need to set only two properties:

  • war –the filesystem path to the web application file/directory.

  • contextPath –the context path to use for the web application.

For example, here is a descriptor file that deploys the file /opt/myapp/myapp.war to the context path /wiki:


<?xml version="1.0"  encoding="ISO-8859-1"?>
<!DOCTYPE Configure PUBLIC "-//Jetty//Configure//EN" "http://www.eclipse.org/jetty/configure.dtd">

<Configure class="org.eclipse.jetty.webapp.WebAppContext">
  <Set name="contextPath">/wiki</Set>
  <Set name="war">/opt/myapp/myapp.war</Set>
</Configure>

        

Note

You can use the SystemProperty and Property elements in your descriptor file. For example, if you set the system property myapp.home=/opt/myapp, you can rewrite the previous example as:


<?xml version="1.0"  encoding="ISO-8859-1"?>
<!DOCTYPE Configure PUBLIC "-//Jetty//Configure//EN" "http://www.eclipse.org/jetty/configure.dtd">

<Configure class="org.eclipse.jetty.webapp.WebAppContext">
  <Set name="contextPath">/wiki</Set>
  <Set name="war"><SystemProperty name="myapp.home"/>/myapp.war</Set>
</Configure>

        

If you need to change the home path for your application, you can simply change the system property. This is useful if you frequently switch among multiple versions of an app.

Configuring Advanced Descriptor Files

If you look at the documentation for the WebAppContext class, you notice that there are a lot more properties than just the two mentioned above. Here are some examples that configure advanced optons with your descriptor file.

This first example tells Jetty not to expand the WAR file when deploying it. This can help make it clear that people should not be making changes to the temporary unpacked WAR because such changes do not persist, and therefore do not apply the next time the web application deploys.


<?xml version="1.0"  encoding="ISO-8859-1"?>
<!DOCTYPE Configure PUBLIC "-//Jetty//Configure//EN" "http://www.eclipse.org/jetty/configure.dtd">

<Configure class="org.eclipse.jetty.webapp.WebAppContext">
  <Set name="contextPath">/wiki</Set>
  <Set name="war"><SystemProperty name="myapp.home"/>/myapp.war</Set>
  <Set name="extractWAR">false</Set>
</Configure>

        

The next example retrieves the JavaEE Servlet context and sets an initialization parameter on it. You can also use the setAttribute method to set a Servlet context attribute. However, since the web.xml for the web application is processed after the deployment descriptor, the web.xml values overwrite like-named attributes from the deployment descriptor.


<?xml version="1.0"  encoding="ISO-8859-1"?>
<!DOCTYPE Configure PUBLIC "-//Jetty//Configure//EN" "http://www.eclipse.org/jetty/configure.dtd">

<Configure class="org.eclipse.jetty.webapp.WebAppContext">
  <Set name="contextPath">/wiki</Set>
  <Set name="war"><SystemProperty name="myapp.home"/>/myapp.war</Set>
  <Get name="ServletContext">
     <Call name="setInitParameter">
       <Arg>myapp.config</Arg>
       <Arg><SystemProperty name="myapp.home">/config/app-config.xml</Arg>
    </Call>
  </Get>
</Configure>

        

The following example sets a special web.xml override descriptor. This descriptor is processed after the web application's web.xml, so may override like-named attributes. This feature is useful if you want to add parameters or additional Servlet mappings without breaking open a packed WAR file.


<?xml version="1.0"  encoding="ISO-8859-1"?>
<!DOCTYPE Configure PUBLIC "-//Jetty//Configure//EN" "http://www.eclipse.org/jetty/configure.dtd">

<Configure class="org.eclipse.jetty.webapp.WebAppContext">
  <Set name="contextPath">/wiki</Set>
  <Set name="war"><SystemProperty name="myapp.home"/>/myapp.war</Set>
  <Set name="overrideDescriptor">/opt/myapp/overlay-web.xml</Set>
</Configure>

        

The next example configures not only the web application context, but also a database connection pool (see ??? that our application can then use. If the web.xml does not include a reference to this data source, you can use the override descriptor mechanism (the previous example), to include it.


<?xml version="1.0"  encoding="ISO-8859-1"?>
<!DOCTYPE Configure PUBLIC "-//Jetty//Configure//EN" "http://www.eclipse.org/jetty/configure.dtd">

<Configure class="org.eclipse.jetty.webapp.WebAppContext">
  <Set name="contextPath">/wiki</Set>
  <Set name="war"><SystemProperty name="myapp.home"/>/myapp.war</Set>
</Configure>

<New id="DSTest" class="org.eclipse.jetty.plus.jndi.Resource">
  <Arg></Arg>
  <Arg>jdbc/DSTest</Arg>
  <Arg>
    <New class="org.apache.commons.dbcp.BasicDataSource">
      <Set name="driverClassName">org.some.Driver</Set>
      <Set name="url">jdbc.url</Set>
      <Set name="username">jdbc.user</Set>
      <Set name="password">jdbc.pass</Set>
    </New>
  </Arg>
</New>

        

Jetty Maven Plugin

If you develop your web application as a Maven project, you can deploy it in Jetty with mvn jetty:run, using the Configuring the Jetty Maven Plugin.

Maven lets you build your web applications by overlaying on other template web applications (for example, CometD) and manages the transitive dependencies needed to populate WEB-INF/lib.

Using the OSGi Web Application Bundle

TBD

Using Embedded Jetty

You can also deploy web applications into embedded Jetty, either via direct configuration or via configuration of a deployer. For an example see ???.

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