remm 2004/02/05 08:05:31
Modified: webapps/docs balancer-howto.xml cluster-howto.xml
project.xml
Log:
- Document other methods for load balancing.
- The mod_rewrite + mod_proxy one is untested (at least by me; Pier did it).
Revision Changes Path
1.3 +117 -9 jakarta-tomcat-catalina/webapps/docs/balancer-howto.xml
Index: balancer-howto.xml
===================================================================
RCS file: /home/cvs/jakarta-tomcat-catalina/webapps/docs/balancer-howto.xml,v
retrieving revision 1.2
retrieving revision 1.3
diff -u -r1.2 -r1.3
--- balancer-howto.xml 25 Nov 2003 18:38:49 -0000 1.2
+++ balancer-howto.xml 5 Feb 2004 16:05:31 -0000 1.3
@@ -8,13 +8,119 @@
<properties>
<author email="[EMAIL PROTECTED]">Yoav Shapira</author>
+ <author>Remy Maucherat</author>
+ <author>Andy Oliver</author>
<title>Load Balancer HOW-TO</title>
</properties>
<body>
+<section name="Table of Contents">
+<p>
+<a href="#Using the JK native connector">
+Using the JK native connector</a><br />
+<a href="#Using Apache 2 with mod_proxy and mod_rewrite">
+Using Apache 2 with mod_proxy and mod_rewrite</a><br />
+<a href="#Using the balancer webapp">Using the balancer webapp</a><br />
+</p>
+</section>
+
+<section name="Using the JK native connector">
+
+Please refer to the JK documentation.
+
+</section>
-<section name="Overview">
+<section name="Using Apache 2 with mod_proxy and mod_rewrite">
+
+<subsection name="Overview">
+
+<p>
+It is possible to use Apache 2, with mod_proxy and mod_rewrite, to load balance
+requests to a set of Tomcat servers, using the HTTP protocol rather than AJP.
+Although it does not have any advanced load balancing or failover strategies,
+it is very easy to setup.
+</p>
+
+<p>
+Thanks to Pier Fumagalli for helping document this method.
+</p>
+
+</subsection>
+
+<subsection name="Configuring Tomcat">
+
+<p>
+Edit <code>$CATALINA_HOME/conf/server.xml</code>, and find the Engine element
+and add an attribute called jvmRoute. Set its value to LB1.
+</p>
+
+<source>
+<Engine name="MainEngine" defaultHost="localhost" jvmRoute="LB1">
+</source>
+
+<p>
+Do the same for each server in the group, giving each a different ID: LB2,
+LB3, ...
+</p>
+
+</subsection>
+
+<subsection name="Apache 2 configuration">
+
+<p>
+First we must create a rewrite map (for mod_rewrite) (balancing.conf):
+</p>
+
+<source>
+LB1 tomcat1.foo.com:8080
+LB2 tomcat2.foo.com:8080
+LB3 tomcat3.foo.com:8888
+ALL tomcat1.foo.com:8080|tomcat2.foo.com:8080|tomcat3.foo.com:8888
+</source>
+
+<p>
+This means each worker is associated with a specific server and port. The name
+associated with each node <strong>must</strong> match the one used for the
+jvmRoute attribute specified on the Engine element of each node's server.xml.
+</p>
+
+<p>
+In <code>httpd.conf</code>:
+</p>
+
+<source>RewriteMap SERVERS rnd:/usr/local/httpd/conf/servers.conf
+
+<Location /webapp>
+ RewriteEngine On
+
+ RewriteCond "%{HTTP_COOKIE}"
"(^|;\s*)jsessionid=\w*\.(\w+)($|;)"
+ RewriteRule "(.*)"
"http://${SERVERS:%2}%{REQUEST_URI}"; [P,L]
+ RewriteRule "^.*;jsessionid=\w*\.(\w+)($|;)"
"http://${SERVERS:$1}%{REQUEST_URI}"; [P,L]
+ RewriteRule "(.*)"
"http://${SERVERS:ALL}%{REQUEST_URI}"; [P,L]
+</Location>
+</source>
+
+<p>
+The first entry means that we want to load the server map which we
+created. The "ALL" entry in the server map will affect those users who
+do not yet have a session ID. Meaning the session cookie which Tomcat
+creates will have the LBx id in it, the other entries will govern which
+host we're directed to.
+</p>
+
+<p>The rewrite rules govern those users with a cookie. Apache will
+rewrite the URL and point you to one of the instances of Tomcat. This
+is vodoo but it should work.
+</p>
+
+</subsection>
+
+</section>
+
+<section name="Using the balancer webapp">
+
+<subsection name="Overview">
<p>
Tomcat 5.0.15 and later ships with a webapp named balancer. This is
@@ -30,9 +136,9 @@
to use a filter to redirect traffic. If you wish to redirect traffic
using a servlet, you may use any servlet container.
</p>
-</section>
+</subsection>
-<section name="Sample Configuration">
+<subsection name="Sample Configuration">
<p>
The default balancer installation uses a single filter, BalancerFilter,
mapped to all requests (url-pattern /*). The filter reads its rules
@@ -53,9 +159,9 @@
http://localhost:8080/balancer/BlahBlah?paramName=paramValue will
be redirected to http://www.yahoo.com.
</p>
-</section>
+</subsection>
-<section name="Balancer Rules">
+<subsection name="Balancer Rules">
<p>
A <i>Rule</i> in the balancer system is a combination of
a request matching criterion and a redirection URL for
@@ -85,9 +191,9 @@
in the Servlet Specification. Each filter will have
its own RuleChain.
</p>
-</section>
+</subsection>
-<section name="How it Works">
+<subsection name="How it Works">
<p>
<ol>
<li>You write a rules configuration file containing various
@@ -104,13 +210,15 @@
</ol>
</p>
-</section>
+</subsection>
-<section name="Comments">
+<subsection name="Comments">
<p>
Please direct questions, comments, suggestions, etc. to the
tomcat-user mailing list. Thank you.
</p>
+</subsection>
+
</section>
</body>
1.5 +2 -2 jakarta-tomcat-catalina/webapps/docs/cluster-howto.xml
Index: cluster-howto.xml
===================================================================
RCS file: /home/cvs/jakarta-tomcat-catalina/webapps/docs/cluster-howto.xml,v
retrieving revision 1.4
retrieving revision 1.5
diff -u -r1.4 -r1.5
--- cluster-howto.xml 9 Jan 2004 23:36:34 -0000 1.4
+++ cluster-howto.xml 5 Feb 2004 16:05:31 -0000 1.5
@@ -26,8 +26,8 @@
attribute is unique for each instance.</li>
<li>Make sure your <code>web.xml</code> has the <code><distributable/></code>
element</li>
</ul>
-<p>Then all you have to do is start Tomcat, I suggest using <a
href="http://balance.sourceforge.net";>Balance</a>
- as a load balancer. Apache/mod_jk will also do or hardware of course</p>
+<p>Load balancing can be achieved through many techniques, as seen in the
+<a href="balancer-howto.html">Load Balancing</a> chapter.</p>
<p>Note: Remember that your session state is tracked by a cookie, so your URL must
look the same from the out
side otherwise, a new session will be created.</p>
<p>Note: Clustering support currently requires the JDK version 1.4 or later.</p>
1.20 +1 -1 jakarta-tomcat-catalina/webapps/docs/project.xml
Index: project.xml
===================================================================
RCS file: /home/cvs/jakarta-tomcat-catalina/webapps/docs/project.xml,v
retrieving revision 1.19
retrieving revision 1.20
diff -u -r1.19 -r1.20
--- project.xml 13 Dec 2003 17:21:21 -0000 1.19
+++ project.xml 5 Feb 2004 16:05:31 -0000 1.20
@@ -37,7 +37,7 @@
href="mbeans-descriptor-howto.html"/>
<item name="17) Default Servlet" href="default-servlet.html"/>
<item name="18) Clustering" href="cluster-howto.html"/>
- <item name="19) Balancer" href="balancer-howto.html"/>
+ <item name="19) Load Balancer" href="balancer-howto.html"/>
</menu>
<menu name="Reference">
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