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[[configuring-virtual-hosts]]
=== Configuring Virtual Hosts

A virtual host is an alternative name, registered in DNS, for an IP address such that multiple domain names will resolve to the same IP of a shared server instance.
If the content to be served to the aliases names is link:#different-virtual-hosts-different-contexts[different], then a virtual host needs to be configured for each deployed link:{JDURL}/org/eclipse/jetty/server/handler/ContextHandler.html[context] to indicate which names a context will respond to.

Virtual hosts are set on a link:{JDURL}/org/eclipse/jetty/server/handler/ContextHandler.html[context] by calling the link:{JDURL}/org/eclipse/jetty/server/handler/ContextHandler.html#setVirtualHosts-java.lang.String:A-[`setVirtualHosts`] or link:{JDURL}/org/eclipse/jetty/server/handler/ContextHandler.html#addVirtualHosts-java.lang.String:A-[`addVirtualHost`] method which can be done in several ways:

* Using a link:#deployable-descriptor-file[context XML] file in the webapps directory (see the example in link:{SRCDIR}/tests/test-webapps/test-jetty-webapp/src/main/config/demo-base/webapps/test.xml[test.xml] in the Jetty distribution).
* Creating a link:#deployment-architecture[custom deployer] with a binding to configure virtual hosts for all contexts found in the same `webapps` directory.
* Calling the link:{JDURL}/org/eclipse/jetty/server/handler/ContextHandler.html#setVirtualHosts-java.lang.String:A-[API] directly on an link:#advanced-embedding[embedded] usage.
* Using a `WEB-INF/jetty-web.xml` file (now deprecated).

[[configuring-a-virtual-host]]
==== Virtual Host Names

Jetty supports the following styles of virtual host name:

www.hostname.com::
  A fully qualified host name. It is important to list all variants as a site may receive traffic from both www.hostname.com and just hostname.com
*.hostname.com::
  A wildcard qualified host which will match only one level of arbitrary names.
  *.foo.com will match www.foo.com and m.foo.com, but not www.other.foo.com
10.0.0.2::
  An IP address may be given as a virtual host name to indicate that a context should handle requests received on that server port that do not have a host name specified (HTTP/0.9 or HTTP/1.0).
@ConnectorName::
  A connector name, which is not strictly a virtual host, but instead will only match requests that are received on connectors that have a matching name set with  link:{JDURL}/org/eclipse/jetty/server/AbstractConnector.html#setName(java.lang.String)[Connector.setName(String)].
www.√integral.com::
  Non-ASCII and  http://en.wikipedia.org/wiki/Internationalized_domain_name[IDN] domain names can be set as virtual hosts using http://en.wikipedia.org/wiki/Punycode[Puny Code] equivalents that may be obtained from a http://network-tools.com/idn-convert.asp[Punycode/IDN converters].
  For example if the non-ASCII domain name `www.√integral.com` is given to a browser, then it will make a request that uses the domain name `www.xn--integral-7g7d.com`, which is the name that should be added as the virtual host name.

==== Example Virtual Host Configuration

Virtual hosts can be used with any context that is a subclass of link:{JDURL}/org/eclipse/jetty/server/handler/ContextHandler.html[ContextHandler].
Lets look at an example where we configure a web application - represented by the link:{JDURL}/org/eclipse/jetty/webapp/WebAppContext.html[WebAppContext] class - with virtual hosts.
You supply a list of IP addresses and names at which the web application is reachable, such as the following:

* `333.444.555.666`
* `127.0.0.1`
* `www.blah.com`
* `www.blah.net`
* `www.blah.org`

Suppose you have a webapp called `blah.war`, that you want all of the above names and addresses to be served at path "`/blah`".
Here's how you would configure the virtual hosts with a link:#deployable-descriptor-file[context XML] file:

[source, xml, subs="{sub-order}"]
----
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE Configure PUBLIC "-//Jetty//Configure//EN" "http://www.eclipse.org/jetty/configure_9_3.dtd">

<Configure class="org.eclipse.jetty.webapp.WebAppContext">
  <Set name="contextPath">/blah</Set>
  <Set name="war"><Property name="jetty.webapps"/>blah.war</Set>
  <Set name="virtualHosts">
    <Array type="java.lang.String">
      <Item>333.444.555.666</Item>
      <Item>127.0.0.1</Item>
      <Item>www.blah.com</Item>
      <Item>www.blah.net</Item>
      <Item>www.blah.org</Item>
    </Array>
  </Set>
</Configure>
----

[[different-virtual-hosts-different-contexts]]
==== Using Different Sets of Virtual Hosts to Select Different Contexts

You can configure different contexts to respond on different virtual hosts by supplying a specific list of virtual hosts for each one.

For example, suppose your imaginary machine has these DNS names:

* `www.blah.com`
* `www.blah.net`
* `www.blah.org`
* `www.other.com`
* `www.other.net`
* `www.other.org`

Suppose also you have 2 webapps, one called `blah.war` that you would like served from the `*.blah.*` names, and one called `other.war` that you want served only from the `*.other.*` names.

Using the method of preparing link:#deployable-descriptor-file[contextXML] files, one for each webapp yields the following:

For `blah` webapp:

[source, xml, subs="{sub-order}"]
----
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE Configure PUBLIC "-//Jetty//Configure//EN" "http://www.eclipse.org/jetty/configure_9_3.dtd">

<Configure class="org.eclipse.jetty.webapp.WebAppContext">
  <Set name="contextPath">/blah</Set>
  <Set name="war"><Property name="jetty.webapps"/>/blah.war</Set>
  <Set name="virtualHosts">
    <Array type="java.lang.String">
      <Item>www.blah.com</Item>
      <Item>www.blah.net</Item>
      <Item>www.blah.org</Item>
    </Array>
  </Set>
</Configure>
----

These URLs now resolve to the blah context (ie `blah.war`):

* `http://www.blah.com/blah`
* `http://www.blah.net/blah`
* `http://www.blah.org/blah`

For `other` webapp:

[source, xml, subs="{sub-order}"]
----
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE Configure PUBLIC "-//Jetty//Configure//EN" "http://www.eclipse.org/jetty/configure_9_3.dtd">

<Configure class="org.eclipse.jetty.webapp.WebAppContext">
  <Set name="contextPath">/other</Set>
  <Set name="war"><Property name="jetty.webapps"/>/other.war</Set>
  <Set name="virtualHosts">
    <Array type="java.lang.String">
      <Item>www.other.com</Item>
      <Item>www.other.net</Item>
      <Item>www.other.org</Item>
    </Array>
  </Set>
</Configure>
----

These URLs now resolve to the other context (i.e. `other.war`):

* `http://www.other.com/other`
* `http://www.other.net/other`
* `http://www.other.org/other`

[[different-virtual-hosts-different-context-same-path]]
==== Using Different Sets of Virtual Hosts to Select Different Contexts at the Same Context Path

In the previous section we setup 2 different contexts to be served from different virtual hosts at _different_ context paths.
However, there is no requirement that the context paths must be distinct: you may use the same context path for multiple contexts, and use virtual hosts to determine which one is served for a given request.

Consider an example where we have the same set of DNS names as before, and the same webapps `blah.war` and `other.war`. We still want `blah.war` to be served in response to hostnames of `*.blah.*`, and we still want `other.war` to be served in response to `*.other.*` names.
However, we would like__all__ of our clients to use the `"/"` context path, no matter which context is being targeted.

In other words, we want all of the following URLs to map to `blah.war`:

* `http://www.blah.com/`
* `http://www.blah.net/`
* `http://www.blah.org/`

Similarly, we want the following URLs to map to `other.war`:

* `http://www.other.com/`
* `http://www.other.net/`
* `http://www.other.org/`

To achieve this, we simply use the same context path of `/` for each of our webapps, while still applying our different set of virtual host names.

For foo webapp:

[source, xml, subs="{sub-order}"]
----
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE Configure PUBLIC "-//Jetty//Configure//EN" "http://www.eclipse.org/jetty/configure_9_3.dtd">

<Configure class="org.eclipse.jetty.webapp.WebAppContext">
  <Set name="contextPath">/</Set>
  <Set name="war"><Property name="jetty.webapps"/>/foo.war</Set>
  <Set name="virtualHosts">
    <Array type="java.lang.String">
      <Item>www.blah.com</Item>
      <Item>www.blah.net</Item>
      <Item>www.blah.org</Item>
    </Array>
  </Set>
</Configure>
----

For bar webapp:

[source, xml, subs="{sub-order}"]
----
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE Configure PUBLIC "-//Jetty//Configure//EN" "http://www.eclipse.org/jetty/configure_9_3.dtd">

<Configure class="org.eclipse.jetty.webapp.WebAppContext">
  <Set name="contextPath">/</Set>
  <Set name="war"><Property name="jetty.webapps"/>/bar.war</Set>
  <Set name="virtualHosts">
    <Array type="java.lang.String">
      <Item>www.other.com</Item>
      <Item>www.other.net</Item>
      <Item>www.other.org</Item>
    </Array>
  </Set>
</Configure>
----
