Jetty allows for deploying an arbitrary context or web application by monitoring a directory for changes. If a web application or a context descriptor is added to the directory, Jetty’s DeploymentManager (DM) deploys a new context. If a context descriptor is touched or updated, the DM stops, reconfigures, and redeploys its context. If a context is removed, the DM stops it and removes it from the server.

This behavior can be controlled by configuring WebAppProvider properties.

The default location for this configuration is in the ${jetty.home}/etc/jetty-deploy.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="addBean">
    <Arg>
      <New id="DeploymentManager" class="org.eclipse.jetty.deploy.DeploymentManager">
        <Set name="contexts">
          <Ref refid="Contexts" />
        </Set>
        <Call name="setContextAttribute">
          <Arg>org.eclipse.jetty.server.webapp.ContainerIncludeJarPattern</Arg>
          <Arg>.*/[^/]*servlet-api-[^/]*\.jar$|.*/javax.servlet.jsp.jstl-.*\.jar$|.*/org.apache.taglibs.taglibs-standard-impl-.*\.jar$</Arg>
        </Call>

        <Call id="webappprovider" name="addAppProvider">
          <Arg>
            <New class="org.eclipse.jetty.deploy.providers.WebAppProvider">
              <Set name="monitoredDirName"><Property name="jetty.base" default="." />/<Property name="jetty.deploy.monitoredDir" deprecated="jetty.deploy.monitoredDirName" default="webapps"/></Set>
              <Set name="defaultsDescriptor"><Property name="jetty.home" default="." />/etc/webdefault.xml</Set>
              <Set name="scanInterval"><Property name="jetty.deploy.scanInterval" default="1"/></Set>
              <Set name="extractWars"><Property name="jetty.deploy.extractWars" default="true"/></Set>
            </New>
          </Arg>
        </Call>
      </New>
    </Arg>
  </Call>
</Configure>

See Understanding the Default WebAppProvider for more configuration details.

See also Deployment Architecture for detailed conceptual information.