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From Apache Wiki <wikidi...@apache.org>
Subject [Tomcat Wiki] Update of "TomcatDevelopmentVirtualHosts" by MarkEggers
Date Fri, 07 May 2010 01:54:34 GMT
Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Tomcat Wiki" for change notification.

The "TomcatDevelopmentVirtualHosts" page has been changed by MarkEggers.
http://wiki.apache.org/tomcat/TomcatDevelopmentVirtualHosts

--------------------------------------------------

New page:
= Tomcat Virtual Hosts Development Environment =
== Introduction ==
This document describes a clean way to create Tomcat virtual hosts in a development environment.
This setup will not work as is for a production environment, since the Tomcat virtual hosts
described by this document will not be visible except on the local host. However, this document
can be used as a basis for creating a production Tomcat virtual host environment.

This document is based on a response I originally wrote concerning logging issues and Tomcat
virtual hosts.

== Environments ==
I use primarily the following two environments when developing concepts and testing ideas.
||<tablewidth="400px" tableheight="365px"style="font-weight: bold;">Component ||<style="font-weight:
bold;">Version ||
||OS ||Fedora 11 32 bit ||
||JDK/JRE ||1.6.0_20 ||
||Tomcat ||6.0.26 ||
||IDE ||!NetBeans 6.8 ||
||Spring ||2.5 (provided with !NetBeans) ||
|| || ||
||OS ||Windows/XP Professional SP 4 32 bit ||
||JDK/JRE ||1.6.0_20 ||
||Tomcat ||6.0.26 ||
||IDE ||!NetBeans 6.8 ||
||Spring ||2.5 (provided with !NetBeans) ||




I am reworking the Spring Developer's Notebook bike store example so I can understand Spring
testing and the use of mock objects. I've also added logging to this application. Logging
is provided by Apache's commons-logging, since Spring ships with the commons-logging package.
The back end logging provider is Apache's log4j.

I've run into a lot of "interesting" issues, mostly having to do with Spring test libraries
versus JUnit versus mock objects. However, that's a topic for another discussion.

== Directory Structure ==
In order to create virtual hosts, do the following:

 1. Create a separate directory for each host '''outside of $CATALINA_HOME/webapps'''
 1. Underneath each directory, create a webapps directory.

For example, here is a sample directory structure for hosts foo and bar.

=== Windows Environment ===
Tomcat is located in C:\Apache\apache-tomcat-6.0.26. While recent versions of Tomcat and Apache
HTTPD manage spaces in directory names, I prefer to have my services live outside of C:\Program
Files.
||<tablewidth="425px"style="font-weight: bold;">Hostname ||Location ||
||localhost ||C:\Apache\apache-tomcat-6.0.26\webapps ||
||foo ||C:\Apache\hosts\foo-host\webapps ||
||bar ||C:\Apache\hosts\bar-host\webapps ||




=== Linux Environment ===
Tomcat is located in ~/Apache/apache-tomcat-6.0.26. This is a development copy and lives in
my home directory. I can easily start, stop, deploy, undeploy, and make changes to this Tomcat
server both from the command line and from within my development environment.
||<tablewidth="425px"style="font-weight: bold;">Hostname ||Location ||
||localhost ||~/Apache/apache-tomcat-6.0.26/webapps ||
||foo ||~Apache/hosts/foo-host/webapps ||
||bar ||~Apache/hosts/bar-host/webapps ||




=== Environment Notes ===
Putting the virtual host directory structure outside of the Tomcat installation provides the
following advantages..

 * When Tomcat is upgraded, virtual hosts are not a concern
 * A pristine Tomcat environment is preserved, which can be useful for debugging
 * Creating new virtual hosts is easy, and does not disturb a running Tomcat

Creating a hosts/<host-name>/webapps structure provides several advantages as well.

 * All the hosts are located in one directory, making it easy to move, change permissions,
or otherwise manage a collection of virtual hosts
 * Provides a consistent and easily understood naming convention
 * the hosts/<host-name> location provides a good place to locate cross-context web
applications such as [[http://lucene.apache.org/solr/|Solr]]

== Tomcat Configuration ==
=== Server.xml ===
To create virtual hosts, I just copied the original locahost entry for the foo and bar hosts.
I changed the name and appBase values to fit the targeted hosts. The resulting files (Windows
and Linux) are shown below. Adjust those locations to reflect your directory structure.

==== Server.xml fragment for Windows ====
{{{
<Host name="localhost"  appBase="webapps"
  unpackWARs="true" autoDeploy="true"
  xmlValidation="false" xmlNamespaceAware="false">
</Host>

<Host name="foo"  appBase="C:/Apache/hosts/foo-host/webapps"
  unpackWARs="true" autoDeploy="true"
  xmlValidation="false" xmlNamespaceAware="false">
</Host>

<Host name="bar"  appBase="C:/Apache/hosts/bar-host/webapps"
  unpackWARs="true" autoDeploy="true"
  xmlValidation="false" xmlNamespaceAware="false">
</Host>
}}}
==== Server.xml fragment for Linux ====
{{{
<Host name="localhost"  appBase="webapps"
  unpackWARs="true" autoDeploy="true"
  xmlValidation="false" xmlNamespaceAware="false">
</Host>

<Host name="foo"  appBase="/home/mdeggers/Apache/hosts/foo-host/webapps"
  unpackWARs="true" autoDeploy="true"
  xmlValidation="false" xmlNamespaceAware="false">
</Host>

<Host name="bar"  appBase="/home/mdeggers/Apache/hosts/bar-host/webapps"
  unpackWARs="true" autoDeploy="true"
  xmlValidation="false" xmlNamespaceAware="false">
</Host>
}}}
Note that I didn't change any of the logging prefixes and suffixes, so all common logging
gets mixed together. Since this is just a proof of concept, I don't really mind.

=== Application Setup ===
I like having both the default web page and the manager application available for each virtual
host in a development environment. This provides me with a couple of advantages.

 * Applications can be managed on a virtual host basis without copying war files around
 * I know that the Tomcat virtual host is running even if I've broken the web application
for that particular virtual host

To do this, use the following steps.

 1. Copy manager.xml from $CATALINA_HOME/conf/Catalina/localhost to each of the virtual host
configuration directories:
  1. For virtual host '''foo''', this means '''manager.xml''' gets copied into $CATALINA_HOME/conf/Catalina/'''foo'''
  1. For virtual host '''bar''', this means '''manager.xml''' gets copied into $CATALINA_HOME/conf/Catalina/'''bar'''
 1. Copy the ROOT application from $CATALINA_HOME/webapps to each of the virtual host webapp
directories
  1. For virtual host '''foo''', this means copying '''ROOT''' to '''hosts/foo-host/webapps'''
(full path depends on actual location to match the '''server.xml entry''')
  1. For virtual host '''bar''', this means copying '''ROOT''' to '''hosts/bar-host/webapps'''
(full path depends on actual location to match the '''server.xml entry''')
 1. Copy the manager application from $CATALINA_HOME/webapps to each of the  virtual host
webapp directories
  1. For virtual host '''foo''', this  means copying '''manager''' to '''hosts/foo-host/webapps'''
(full path  depends on actual location to match the '''server.xml  entry''')
  1. For virtual host '''bar''', this  means copying '''manager''' to '''hosts/bar-host/webapps'''
(full path  depends on actual location to match the '''server.xml  entry''')

=== Network Setup ===
In order to browse to '''http://foo:<port>/<application>''' and '''http://bar:<port>/<application>''',
hosts foo and bar have to be resolved to an IP address. The simplest way to accomplish this
is to create entries for foo and bar in the appropriate hosts file and associate the entries
with 127.0.0.1 (locahost). Note that by setting up the IP addresses in this fashion, '''the
virtual hosts will only be visible on your local machine'''.

If these virtual hosts need to be visible from some other machine, then an externally visible
IP address will have to be used (not 127.0.0.1) and an entry into the remote host machine's
host file will have to be made. Alternatively, the IP address and fully qualified domain name
will have to be entered into a domain name server. Explaining these options are beyond the
scope of this document.

==== Windows Network Setup for Virtual Hosts ====
Edit the hosts file for Windows. This is normally found in %windir%\system32\drivers\etc.
You will need administrator rights in order to do this. For my machine this is C:\WINNT\system32\drivers\etc
since this machine was upgraded from Windows/2000 Professional.

Add a line for each of your virtual hosts. The line looks like the following:

{{{
    127.0.0.1    <hostname>
}}}
For the example above, there are two lines which read:

{{{
    127.0.0.1    foo
    127.0.0.1    bar
}}}
==== Linux Network Setup for Virtual Hosts ====
The hosts file for Linux is located in /etc. You will need root permission in order to do
this. The entries are the same as those for the Windows hosts file.

There is an additional consideration for Linux. Linux has a file called /etc/nsswitch.conf
which controls how various name resolution operations are performed. Make sure that for hosts,
the files directive is present. For example:

{{{
hosts:dns files
}}}
If you do not use DNS, then obviously do not have the dns entry present. The important entry
is files, so that Linux will (eventually) look at /etc/hosts for name to IP address resolution.

== Results and Testing ==
=== Results ===
Upon starting Tomcat, all three hosts should be visible at localhost:8080, foo:8080, and bar:8080
(if you have not changed the default connector port). This is where having the default ROOT
application is handy. If you do not see the Tomcat home page for each of the virtual hosts,
then something is wrong with the setup.

The manager application should be available for each virtual host as well. The passwords will
all be the same, since the web.xml is pointing to the same global resource reference. Having
different passwords for each virtual host can be accomplised by pointing either to different
global resources or by pointing to a suitable entry in virtual host's manager.xml file. Both
changes are beyond the scope of this document.

=== Log Testing ===
==== Application Notes ====
In order to test that each virtual host was acting independently, I made use of the [[http://oreilly.com/catalog/9780596009106/|Spring
Developer's Notebook]] bike shop application. I added some logging via commons-logging to
!BikeValidator.java. The exact syntax isn't important. What is important is that I added logging
statements for several different failed validations. I could then cause a specific validation
failure on a particular virtual host. By looking at the log files, I could make sure that
the validation error was only logged on the virtual host where it occured.

To accomplish this, I created three war files, one for each virtual host. The only change
that was made was to the log4j.properties file. The complete log4j.properties file for the
localhost virtual host is shown below.

{{{
### direct messages to file dnb-02.log ###
log4j.appender.file=org.apache.log4j.FileAppender log4j.appender.file.File=${catalina.home}/logs/dnb-02.log
log4j.appender.file.layout=org.apache.log4j.PatternLayout log4j.appender.file.layout.ConversionPattern=%d{ABSOLUTE}
%5p %c{1}:%L - %m%n

### set log levels - for more verbose logging change 'info' to 'debug' ###
log4j.rootLogger=warn, file

### Spring Framework logging
log4j.logger.org.springframework=info
}}}
'''Important issues to note:'''

 * Change the log4j.appder.file name for each log4j.properties file. I used foo-dnb-02.log
and bar-dnb-02.log for virtual hosts foo and bar.
 * '''DO NOT PUT commons-logging or log4j jars in $CATALINA_HOME/lib. '''

==== Test Results ====
After starting Tomcat with three virtual hosts (localhost, foo, and bar), I caused specific
warnings to occur by making invalid entries for editing a bike (no serial number, frame too
small, weight too light, etc.). To verify that the virtual hosts were working as expected,
I verified the following:

 * Three log files were created - dnb-02.log, foo-dnb-02.log, and bar-dnb-02.log
 * Time stamps in the log files were consistent with browser access
 * No duplicate Spring info messages were logged
 * Warning messages from the application were logged
  * Warning messages were in the appropriate files
  * Warning messages had time stamps consistent with the warning

== Conclusion ==
This document demonstrates a simple way to set up virtual hosts in a development environment.
The resulting setup works as expected, maintaining separate management and application logging.
Virtual hosts are easily added, modified, enabled, or disabled. Tomcat upgrades can occur
without impacting the virtual host structure.

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