<html><head><META http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>The Apache Tomcat Connectors - Reference Guide - Configuring Apache</title><meta name="author" value="Mladen Turk"><meta name="email" value="mturk@apache.org"><link href="../../style.css" type="text/css" rel="stylesheet"></head><body bgcolor="#ffffff" text="#000000" link="#525D76" alink="#525D76" vlink="#525D76"><table border="0" width="100%" cellspacing="4"><!--PAGE HEADER--><tr><td colspan="2"><!--TOMCAT LOGO--><a href="http://tomcat.apache.org/"><img src="../../images/tomcat.gif" align="left" alt="Apache Tomcat" border="0"></a><!--APACHE LOGO--><a href="http://www.apache.org/"><img src="http://www.apache.org/images/asf-logo.gif" align="right" alt=" :: Apache Software Foundation" border="0"></a></td></tr><!--HEADER SEPARATOR--><tr><td colspan="2"><hr noshade size="1"></td></tr><tr><!--RIGHT SIDE MAIN BODY--><td width="80%" valign="top" align="left"><table border="0" width="100%" cellspacing="4"><tr><td align="left" valign="top"><h1>The Apache Tomcat Connectors - Reference Guide</h1><h2>Configuring Apache</h2></td><td align="right" valign="top" nowrap="true"><img src="../../images/void.gif" width="1" height="1" vspace="0" hspace="0" border="0" alt=" "></td></tr></table><table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Configuration Directives"><strong>Configuration Directives</strong></a></font></td></tr><tr><td><blockquote>
<p>
Most of the directives are allowed once in the global part of the Apache httpd
configuration and once in every <VirtualHost> elements. Exceptions from this rule are
explicitly listed in the table below.
</p>
<p>
Most values are inherited from the main server to the virtual hosts.
Since version 1.2.20 they can be overwritten in the virtual hosts.
Exceptions from this rule are again explicitly listed in the table below.
See especially JkMountCopy.
</p>
<p><font color="#ff0000">
Warning: If Apache httpd and Tomcat are configured to serve content from
the same filing system location then care must be taken to ensure that httpd is
not able to serve inappropriate content such as the contents of the WEB-INF
directory or JSP source code.
</font></p>
<p>
This could occur if the httpd DocumentRoot
overlaps with a Tomcat Host's appBase or the docBase of any Context. It could
also occur when using the httpd Alias directive with a Tomcat Host's appBase or
the docBase of any Context.
</p>
<p>
Here are the all directives supported by Apache:
</p>
<table border="1" cellpadding="5"><tr><th width="20%" bgcolor="#023264"><font color="#ffffff">Directive</font></th><th width="80%" bgcolor="#023264"><font color="#ffffff">Description</font></th></tr><tr><td align="left" valign="center"><code>JkWorkersFile</code></td><td align="left" valign="center"><p>
The name of a worker file for the Tomcat servlet containers.
<br>
This directive is only allowed once. It must be put into
the global part of the configuration.
<br>
If you don't use the JkWorkerProperty directives, then you must
define your workers with a valid JkWorkersFile. There is no default
value.
</p></td></tr><tr><td align="left" valign="center"><code>JkWorkerProperty</code></td><td align="left" valign="center"><p>
Enables setting worker properties inside Apache configuration file.
The syntax is the same as in the JkWorkersFile (usually workers.properties).
Simply prefix each line with "JkWorkerProperty" to put it directly into
the Apache httpd config files.
<br>
This directive is allowed multiple times.
It must be put into the global part of the configuration.
<br>
If you don't use the JkWorkerProperty directives, then you must
define your workers with a valid JkWorkersFile. There is no default
value.
<br>
This directive is available in jk1.2.7 version and later.
</p></td></tr><tr><td align="left" valign="center"><code>JkShmFile</code></td><td align="left" valign="center"><p>
Shared memory file name. Used only on unix platforms.
The shm file is used by balancer and status workers.
<br>
This directive is only allowed once. It must be put into
the global part of the configuration.
<br>
The default value is logs/jk-runtime-status.
It is highly recommended that the shm file be placed on a local
drive and not an NFS share.
</p>
<p>
The shared memory contains configuration and runtime information for load balancer
workers and their members. It is need in order that all apache children
<ul>
<li>share the same status information for load balancing members (OK, ERROR, ...),</li>
<li>share the information about load taken by the individual workers,</li>
<li>share the information for the parts of the configuration, which are changeable
during runtime by status workers.</li>
</ul>
</p>
</td></tr><tr><td align="left" valign="center"><code>JkShmSize</code></td><td align="left" valign="center"><p>
Size of the shared memory file name.
<br>
This directive is only allowed once. It must be put into
the global part of the configuration.
<br>
The default value depends on the platform. It is usually less than 64KB.
</p></td></tr><tr><td align="left" valign="center"><code>JkMountFile</code></td><td align="left" valign="center"><p>
File containing multiple mappings from a context to a Tomcat worker.
It is usually called uriworkermap.properties.
<br>
For inheritance rules, see: JkMountCopy.
<br>
There is no default value.
</p></td></tr><tr><td align="left" valign="center"><code>JkMountFileReload</code></td><td align="left" valign="center"><p>
This directive configures the reload check interval in seconds.
The JkMountFile is checked periodically for changes.
A changed file gets reloaded automatically. If you set
this directive to "0", reload checking is turned off.
<br>
The default value is 60 seconds.
<br>
This directive has been added in version 1.2.20 of mod_jk.
</p></td></tr><tr><td align="left" valign="center"><code>JkMount</code></td><td align="left" valign="center"><p>
A mount point from a context to a Tomcat worker.
<br>
This directive is allowed multiple times.
It is allowed in the global configuration and in VirtualHost.
<br>
You can also use it inside Location with a different syntax.
Inside Location, one omits the first argument (path),
which gets inherited verbatim from the Location argument.
Whereas <Location /myapp> matches any URI beginning with
"/myapp", any JkMount nested in such a Location block will
only match for requests with exact URI /myapp. Therefore nesting
JkMount in Location is typically not the right thing to do.
<br>
By default JkMount entries are not inherited from the global
server to other VirtualHosts or between VirtualHosts.
For the complete inheritance rules, see: JkMountCopy.
<br>
You might append rule extensions to the worker name.
The extensions are separated from the worker name by a
semicolon ";" using the same syntax as in the
uriworkermap.properties file.
</p></td></tr><tr><td align="left" valign="center"><code>JkUnMount</code></td><td align="left" valign="center"><p>
An exclusion mount point from a context to a Tomcat worker.
All exclusion mounts are checked after mapping a request
to a tomcat worker. If the request maps also to an exclusion,
it will not be forwarded to tomcat, and instead be served locally.
<br>
This directive is allowed multiple times.
It is allowed in the global configuration and in VirtualHost.
<br>
You can also use it inside Location with a different syntax.
Inside Location, one omits the first argument (path),
which gets inherited verbatim from the Location argument.
Whereas <Location /myapp> matches any URI beginning with
"/myapp", any JkUnMount nested in such a Location block will
only match for requests with exact URI /myapp. Therefore nesting
JkUnMount in Location is typically not the right thing to do.
<br>
For inheritance rules, see: JkMountCopy.
<br>
This directive is available in jk1.2.7 version and later.
</p></td></tr><tr><td align="left" valign="center"><code>JkAutoAlias</code></td><td align="left" valign="center"><p>
Automatically Alias webapp context directories into the Apache
document space.
<br>
Care should be taken to ensure that only static content is served via httpd as a
result of using this directive. Any static content served by httpd will bypass any
security constraints defined in the application's web.xml.
<br>
For inheritance rules, see: JkMountCopy.
<br>
There is no default value.
</p></td></tr><tr><td align="left" valign="center"><code>JkMountCopy</code></td><td align="left" valign="center"><p>
If this directive is set to "On" in some virtual server,
the mounts from the global server will be copied to this
virtual server, more precisely all mounts defined by JkMount
or JkUnMount. The Mounts defined by JkMountFile and JkAutoAlias
will only be inherited, if the VirtualHost does not define
it's own JkMountFile or JkAutoAlias.
<br>
If you want all vhost to inherit mounts from the main server,
you can set JkMountCopy to 'All' in the main server.
<br>
This directive is only allowed inside VirtualHost (with value "On")
and in the global server (with value "All").
<br>
The default is Off, so no mounts will be inherited from the global
server to any VirtualHost.
<br>
Starting with version 1.2.26 you can also set it to "All" in the
global virtual server. This will switch the default to On.
</p></td></tr><tr><td align="left" valign="center"><code>JkWorkerIndicator</code></td><td align="left" valign="center"><p>
Name of the Apache environment variable that can be used to set worker names
in combination with SetHandler jakarta-servlet.
<br>
This directive is only allowed once per virtual server.
It is allowed in the global configuration and in VirtualHost.
<br>
The default value is JK_WORKER_NAME.
</p></td></tr><tr><td align="left" valign="center"><code>JkWatchdogInterval</code></td><td align="left" valign="center"><p>
This directive configures the watchdog thread interval in seconds.
The workers are maintained periodically by a background thread
running periodically every watchdog_interval seconds. Worker maintenance
checks for idle connections, corrects load status and is able
to detect backend health status.
<br>
The maintenance only happens, if since the last maintenance at
least <a href="workers.html"><b class="code">worker.maintain</b></a>
seconds have passed. So setting the JkWatchdogInterval
much smaller than <b class="code">worker.maintain</b> is not useful.
<br>
The default value is 0 seconds, meaning the watchdog thread
will not be created, and the maintenance is done in combination
with normal requests instead.
<br>
This directive is only allowed once. It must be put into
the global part of the configuration.
<br>
This directive has been added in version 1.2.27 of mod_jk.
It is available only for httpd 2.x and above using APR libraries
including thread support.
</p></td></tr><tr><td align="left" valign="center"><code>JkLogFile</code></td><td align="left" valign="center"><p>
Full or server relative path to the mod_jk log file.
It will also work with pipe, by using a value of the form "| ...".
<br>
The default value is logs/mod_jk.log.
<br>
Pipes are supported for Apache 1.3 only since version 1.2.16.
The default value exists only since version 1.2.20.
</p></td></tr><tr><td align="left" valign="center"><code>JkLogLevel</code></td><td align="left" valign="center"><p>
The mod_jk log level, can be debug, info, warn
error or trace.
<br>
The default value is info.
</p></td></tr><tr><td align="left" valign="center"><code>JkLogStampFormat</code></td><td align="left" valign="center"><p>
The mod_jk <b>date</b> log format, using an
extended strftime syntax.
This format will be used for the time stamps in the JkLogFile.
The maximum length of the format is 63 characters.
<br>
Starting with version 1.2.24 of mod_jk you can also use %Q
for adding milliseconds to the log and %q for microseconds.
These conversion specifiers are an extension to strftime.
They will only work on platforms with a gettimeofday() function.
You can use %Q and %q only once in the pattern and also not both
together in the same pattern.
<br>
The default value is "[%a %b %d %H:%M:%S %Y] " and beginning
with version 1.2.24 on platforms with a gettimeofday()
function it is "[%a %b %d %H:%M:%S.%Q %Y] ".
</p></td></tr><tr><td align="left" valign="center"><code>JkRequestLogFormat</code></td><td align="left" valign="center"><p>
Request log format string. See detailed description below.
<br>
There is no default value. Without defining a value, the request logging
is turned off.
</p></td></tr><tr><td align="left" valign="center"><code>JkExtractSSL</code></td><td align="left" valign="center"><p>
Turns on SSL processing and information gathering by mod_jk
<br>
The default value is On.
<br>
In order to make SSL data available for mod_jk in Apache, you need to
set <b class="code">SSLOptions +StdEnvVars</b>. For the certificate information you also need
to add <b class="code">SSLOptions +ExportCertData</b>.
</p>
<p>
Specifically, mod_jk will export the following environment variables from
Apache httpd to Tomcat under these request attributes as per the
Servlet Specification 3.0, section 3.8:
</p>
<table>
<tr><th>Env Var</th><th>Request Attribute Name</th><th>Type</th><th>Example</th></tr>
<tr>
<td>SSL_CIPHER<br>(or <b class="code">JkKEYSIZEIndicator</b>)</td>
<td>javax.servlet.request.cipher_suite</td>
<td>java.lang.String</td>
<td>DHE-RSA-AES256-SHA</td>
</tr>
<tr>
<td>SSL_CIPHER_USEKEYSIZE<br>(or <b class="code">JkKEYSIZEIndicator</b>)</td>
<td>javax.servlet.request.key_size</td>
<td>java.lang.Integer</td>
<td>256</td>
</tr>
<tr>
<td>SSL_SESSION_ID<br>(or <b class="code">JkSESSIONIndicator</b>)</td>
<td>javax.servlet.request.ssl_session</td>
<td>java.lang.String</td>
<td>905...32E (a hex string)</td>
</tr>
<tr>
<td>SSL_CLIENT_CERT_CHAIN_<i>n</i><br>(or <b class="code">JkCERTCHAINPrefix</b><i>n</i>)</td>
<td>javax.servlet.request.X509Certificate</td>
<td>java.security.X509Certificate[]</td>
<td>(A chain of certs in ascending order of trust, the first one being
ths client's certificate, the second being the signer of that
certificate, and so on)</td>
</tr>
</table>
<p>
In addition mod_jk sends the name of the SSL protocol used as a proprietary
request attribute named <b class="code">AJP_SSL_PROTOCOL</b>. Modern Tomcat
versions will expose this attribute under the name
<b class="code">org.apache.tomcat.util.net.secure_protocol_version</b>.
This feature has been added in version 1.2.41 of mod_jk. See also
JkSSLPROTOCOLIndicator.
</p>
<p>
For all other SSL-related variables, use <b class="code">JkEnvVar</b> for each
variable you want. Please note that, like <b class="code">JkEnvVar</b>, these
variables are available from the request <i><b>attributes</b></i>, not as
environment variables or as request headers.
</p>
</td></tr><tr><td align="left" valign="center"><code>JkHTTPSIndicator</code></td><td align="left" valign="center"><p>
Name of the Apache environment variable that contains SSL indication.
<br>
The default value is "HTTPS".
</p></td></tr><tr><td align="left" valign="center"><code>JkSSLPROTOCOLIndicator</code></td><td align="left" valign="center"><p>
Name of the Apache environment variable that contains the SSL protocol name.
<br>
The default value is "SSL_PROTOCOL".
<br>
This directive has been added in version 1.2.41 of mod_jk.
</p></td></tr><tr><td align="left" valign="center"><code>JkCERTSIndicator</code></td><td align="left" valign="center"><p>
Name of the Apache environment variable that contains SSL client certificates.
<br>
The default value is "SSL_CLIENT_CERT".
</p></td></tr><tr><td align="left" valign="center"><code>JkCIPHERIndicator</code></td><td align="left" valign="center"><p>
Name of the Apache environment variable that contains SSL client cipher.
<br>
The default value is "SSL_CIPHER".
</p></td></tr><tr><td align="left" valign="center"><code>JkCERTCHAINPrefix</code></td><td align="left" valign="center"><p>
Name of the Apache environment (prefix) that contains SSL client chain certificates.
<br>
The default value is "SSL_CLIENT_CERT_CHAIN_".
</p></td></tr><tr><td align="left" valign="center"><code>JkSESSIONIndicator</code></td><td align="left" valign="center"><p>
Name of the Apache environment variable that contains SSL session.
<br>
The default value is "SSL_SESSION_ID".
</p></td></tr><tr><td align="left" valign="center"><code>JkKEYSIZEIndicator</code></td><td align="left" valign="center"><p>
Name of the Apache environment variable that contains SSL key size in use.
<br>
The default value is "SSL_CIPHER_USEKEYSIZE".
</p></td></tr><tr><td align="left" valign="center"><code>JkLocalNameIndicator</code></td><td align="left" valign="center"><p>
Name of the Apache environment variable which can be used to overwrite
the forwarded local name.
Use this only if you need to adjust the data (see the
<a href="../../common_howto/proxy.html">proxy</a> documentation).
<br>
The default value is "JK_LOCAL_NAME".
<br>
This directive has been added in version 1.2.28 of mod_jk.
</p></td></tr><tr><td align="left" valign="center"><code>JkIgnoreCLIndicator</code></td><td align="left" valign="center"><p>
Name of the Apache environment variable which forces to
ignore an existing Content-Length request header. This can be
used to make mod_jk conpatible with mod_deflate request body
inflation (see <a href="#Advanced Environment Variables">below</a>).
<br>
The default value is "JK_IGNORE_CL".
<br>
This directive has been added in version 1.2.41 of mod_jk.
</p></td></tr><tr><td align="left" valign="center"><code>JkLocalAddrIndicator</code></td><td align="left" valign="center"><p>
Name of the Apache environment variable which can be used to overwrite
the forwarded local IP address.
Use this only if you need to adjust the data (see the
<a href="../../common_howto/proxy.html">proxy</a> documentation).
<br>
The default value is "JK_LOCAL_ADDR".
<br>
This directive has been added in version 1.2.41 of mod_jk.
</p></td></tr><tr><td align="left" valign="center"><code>JkLocalPortIndicator</code></td><td align="left" valign="center"><p>
Name of the Apache environment variable which can be used to overwrite
the forwarded local port.
Use this only if you need to adjust the data (see the
<a href="../../common_howto/proxy.html">proxy</a> documentation).
<br>
The default value is "JK_LOCAL_PORT".
<br>
This directive has been added in version 1.2.28 of mod_jk.
</p></td></tr><tr><td align="left" valign="center"><code>JkRemoteHostIndicator</code></td><td align="left" valign="center"><p>
Name of the Apache environment variable which can be used to overwrite
the forwarded remote (client) host name.
Use this only if you need to adjust the data (see the
<a href="../../common_howto/proxy.html">proxy</a> documentation).
<br>
The default value is "JK_REMOTE_HOST".
<br>
This directive has been added in version 1.2.28 of mod_jk.
</p></td></tr><tr><td align="left" valign="center"><code>JkRemoteAddrIndicator</code></td><td align="left" valign="center"><p>
Name of the Apache environment variable which can be used to overwrite
the forwarded remote (client) IP address.
Use this only if you need to adjust the data (see the
<a href="../../common_howto/proxy.html">proxy</a> documentation).
<br>
The default value is "JK_REMOTE_ADDR".
<br>
This directive has been added in version 1.2.28 of mod_jk.
</p></td></tr><tr><td align="left" valign="center"><code>JkRemotePortIndicator</code></td><td align="left" valign="center"><p>
Name of the Apache environment variable which can be used to overwrite
the forwarded remote (client) IP address.
Use this only if you need to adjust the data (see the
<a href="../../common_howto/proxy.html">proxy</a> documentation).
<br>
The default value is "JK_REMOTE_PORT".
<br>
This directive has been added in version 1.2.32 of mod_jk.
</p></td></tr><tr><td align="left" valign="center"><code>JkRemoteUserIndicator</code></td><td align="left" valign="center"><p>
Name of the Apache environment variable which can be used to overwrite
the forwarded user name.
Use this only if you need to adjust the data (see the
<a href="../../common_howto/proxy.html">proxy</a> documentation).
<br>
The default value is "JK_REMOTE_USER".
<br>
This directive has been added in version 1.2.28 of mod_jk.
</p></td></tr><tr><td align="left" valign="center"><code>JkAuthTypeIndicator</code></td><td align="left" valign="center"><p>
Name of the Apache environment variable which can be used to overwrite
the forwarded authentication type.
Use this only if you need to adjust the data (see the
<a href="../../common_howto/proxy.html">proxy</a> documentation).
<br>
The default value is "JK_AUTH_TYPE".
<br>
This directive has been added in version 1.2.28 of mod_jk.
</p></td></tr><tr><td align="left" valign="center"><code>JkOptions</code></td><td align="left" valign="center"><p>
Set one of more options to configure the mod_jk module. See below for
details about this directive.
<br>
This directive can be used multiple times per virtual server.
<br>
The default value is "ForwardURIProxy" since version 1.2.24.
It was "ForwardURICompatUnparsed" in version 1.2.23 and
"ForwardURICompat" until version 1.2.22.
</p></td></tr><tr><td align="left" valign="center"><code>JkEnvVar</code></td><td align="left" valign="center"><p>
Adds a name and an optional default value of environment variable
that should be sent to servlet-engine as a request attribute.
If the default value is not given explicitly, the variable
will only be send, if it is set during runtime.
<br>
The default is empty, so no additional variables will be sent.
<br>
This directive can be used multiple times per virtual server.
The settings will be merged between the global server and any
virtual server.
<br>
You can retrieve the variables on Tomcat as request attributes
via request.getAttribute(attributeName). Note that the variables
send via JkEnvVar will not be listed in request.getAttributeNames().
<br>
Empty default values are supported since version 1.2.20.
Not sending variables with empty defaults and empty runtime value
has been introduced in version 1.2.21.
</p></td></tr><tr><td align="left" valign="center"><code>JkStripSession</code></td><td align="left" valign="center"><p>
If this directive is set to On in some virtual server,
the session IDs <b class="code">;jsessionid=...</b> will be
removed for URLs which are not forwarded but instead are
handled by the local server.
<br>
This directive is only allowed inside VirtualHost.
<br>
The default is Off.
<br>
This directive has been introduced in version 1.2.21.
<br>With version 1.2.27 and later this directive can have optional
session ID identifier. If not specified it defaults to
<b class="code">;jsessionid</b>.
</p>
</td></tr></table>
</blockquote></td></tr></table><table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td bgcolor="#525D76"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Configuration Directives Types"><strong>Configuration Directives Types</strong></a></font></td></tr><tr><td><blockquote>
<p>
We'll discuss here the mod_jk directive types.
</p>
<table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Define workers"><strong>Define workers</strong></a></font></td></tr><tr><td><blockquote>
<p>
<b>JkWorkersFile</b> specify the location where mod_jk will find the workers definitions.
Take a look at <a href="workers.html">Workers documentation</a> for detailed description.
<div class="example"><pre>
JkWorkersFile /etc/httpd/conf/workers.properties
</pre></div>
<br>
<br>
</p>
</blockquote></td></tr></table>
<table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Logging"><strong>Logging</strong></a></font></td></tr><tr><td><blockquote>
<p>
<b>JkLogFile</b> specify the location where mod_jk is going to place its log file.
</p>
<div class="example"><pre>
JkLogFile /var/log/httpd/mod_jk.log
</pre></div>
<p>
Since JK 1.2.3 for Apache 2.x and JK 1.2.16 for Apache 1.3 this can also
be used for piped logging:
</p>
<div class="example"><pre>
JkLogFile "|/usr/bin/rotatelogs /var/log/httpd/mod_jk.log 86400"
</pre></div>
<p>
<b>JkLogLevel</b>
set the log level between :
</p>
<ul>
<li>
<b>info</b> log will contain standard mod_jk activity (default).
</li>
<li>
<b>warn</b> log will contain non fatal error reports.
</li>
<li>
<b>error</b> log will contain also error reports.
</li>
<li>
<b>debug</b> log will contain all information on mod_jk activity
</li>
<li>
<b>trace</b> log will contain all tracing information on mod_jk activity
</li>
</ul>
<div class="example"><pre>
JkLogLevel info
</pre></div>
<p>
<b class="code">info</b> should be your default selection for normal operations.
<br>
<br>
</p>
<p>
<b>JkLogStampFormat</b> will configure the date/time format found on mod_jk log file.
See above for details.
</p>
<div class="example"><pre>
JkLogStampFormat "[%Y-%m-%d %H:%M:%S.%Q] "
</pre></div>
<p>
<br>
<br>
</p>
<p>
You can log mod_jk information using the Apache standard module <b>mod_log_config</b>.
The module sets several notes in the Apache httpd notes table.
Most of them are are only useful in combination with a load balancer worker.
</p>
<p>
<table border="1" cellpadding="5"><tr><th width="20%" bgcolor="#023264"><font color="#ffffff">Note</font></th><th width="80%" bgcolor="#023264"><font color="#ffffff">Description</font></th></tr><tr><td align="left" valign="center"><code>JK_WORKER_NAME</code></td><td align="left" valign="center">Name of the worker selected by the URI mapping</td></tr><tr><td align="left" valign="center"><code>JK_WORKER_TYPE</code></td><td align="left" valign="center">Type of the worker selected by the URI mapping</td></tr><tr><td align="left" valign="center"><code>JK_WORKER_ROUTE</code></td><td align="left" valign="center">Actual worker name selected by the URI mapping (usually a member of the load balancer).<br>
Before version 1.2.26 only available if JkRequestLogFormat is set.</td></tr><tr><td align="left" valign="center"><code>JK_REQUEST_DURATION</code></td><td align="left" valign="center">Request duration in seconds and microseconds.<br>
Before version 1.2.26 only available if JkRequestLogFormat is set.</td></tr><tr><td align="left" valign="center"><code>JK_LB_FIRST_NAME</code></td><td align="left" valign="center">Load-Balancer: Name of the first worker tried</td></tr><tr><td align="left" valign="center"><code>JK_LB_FIRST_TYPE</code></td><td align="left" valign="center">Load-Balancer: Type of the first worker tried</td></tr><tr><td align="left" valign="center"><code>JK_LB_FIRST_ACCESSED</code></td><td align="left" valign="center">Load-Balancer: Access count for the first worker tried</td></tr><tr><td align="left" valign="center"><code>JK_LB_FIRST_SESSIONS</code></td><td align="left" valign="center">Load-Balancer: Count of created sessions for the first worker tried</td></tr><tr><td align="left" valign="center"><code>JK_LB_FIRST_READ</code></td><td align="left" valign="center">Load-Balancer: Bytes read for the first worker tried</td></tr><tr><td align="left" valign="center"><code>JK_LB_FIRST_TRANSFERRED</code></td><td align="left" valign="center">Load-Balancer: Bytes transferred for the first worker tried</td></tr><tr><td align="left" valign="center"><code>JK_LB_FIRST_ERRORS</code></td><td align="left" valign="center">Load-Balancer: Error count for the first worker tried</td></tr><tr><td align="left" valign="center"><code>JK_LB_FIRST_BUSY</code></td><td align="left" valign="center">Load-Balancer: Busy count for the first worker tried</td></tr><tr><td align="left" valign="center"><code>JK_LB_FIRST_ACTIVATION</code></td><td align="left" valign="center">Load-Balancer: Activation state for the first worker tried</td></tr><tr><td align="left" valign="center"><code>JK_LB_FIRST_STATE</code></td><td align="left" valign="center">Load-Balancer: Error state for the first worker tried</td></tr><tr><td align="left" valign="center"><code>JK_LB_LAST_NAME</code></td><td align="left" valign="center">Load-Balancer: Name of the last worker tried</td></tr><tr><td align="left" valign="center"><code>JK_LB_LAST_TYPE</code></td><td align="left" valign="center">Load-Balancer: Type of the last worker tried</td></tr><tr><td align="left" valign="center"><code>JK_LB_LAST_ACCESSED</code></td><td align="left" valign="center">Load-Balancer: Access count for the last worker tried</td></tr><tr><td align="left" valign="center"><code>JK_LB_LAST_SESSIONS</code></td><td align="left" valign="center">Load-Balancer: Count of created sessions for the last worker tried</td></tr><tr><td align="left" valign="center"><code>JK_LB_LAST_READ</code></td><td align="left" valign="center">Load-Balancer: Bytes read for the last worker tried</td></tr><tr><td align="left" valign="center"><code>JK_LB_LAST_TRANSFERRED</code></td><td align="left" valign="center">Load-Balancer: Bytes transferred for the last worker tried</td></tr><tr><td align="left" valign="center"><code>JK_LB_LAST_ERRORS</code></td><td align="left" valign="center">Load-Balancer: Error count for the last worker tried</td></tr><tr><td align="left" valign="center"><code>JK_LB_LAST_BUSY</code></td><td align="left" valign="center">Load-Balancer: Busy count for the last worker tried</td></tr><tr><td align="left" valign="center"><code>JK_LB_LAST_ACTIVATION</code></td><td align="left" valign="center">Load-Balancer: Activation state for the last worker tried</td></tr><tr><td align="left" valign="center"><code>JK_LB_LAST_STATE</code></td><td align="left" valign="center">Load-Balancer: Error state for the last worker tried</td></tr></table>
<div class="example"><pre>
LogFormat "%h %l %u %t \"%r\" %>s %b %{JK_WORKER_NAME}n %{JK_LB_FIRST_NAME}n \
%{JK_LB_FIRST_BUSY}n %{JK_LB_LAST_NAME}n %{JK_LB_LAST_BUSY}n" mod_jk_log
CustomLog logs/access_log mod_jk_log
</pre></div>
<br>
<br>
</p>
<p>
You can also log a request protocol in the mod_jk log file instead of
the access log. This is not recommended and mostly a backward compatibility
feature. The directive <b>JkRequestLogFormat</b> will configure the format
of this protocol. It gets configured and enabled on a per virtual host basis.
To enable request logging for a virtual host just add a JkRequestLogFormat config.
The syntax of the format string is similar to the Apache LogFormat command,
here is a list of the available request log format options:
</p>
<p>
<table border="1" cellpadding="5"><tr><th width="20%" bgcolor="#023264"><font color="#ffffff">Options</font></th><th width="80%" bgcolor="#023264"><font color="#ffffff">Description</font></th></tr><tr><td align="left" valign="center"><code>%b</code></td><td align="left" valign="center">Bytes sent, excluding HTTP headers (CLF format)</td></tr><tr><td align="left" valign="center"><code>%B</code></td><td align="left" valign="center">Bytes sent, excluding HTTP headers</td></tr><tr><td align="left" valign="center"><code>%H</code></td><td align="left" valign="center">The request protocol</td></tr><tr><td align="left" valign="center"><code>%m</code></td><td align="left" valign="center">The request method</td></tr><tr><td align="left" valign="center"><code>%p</code></td><td align="left" valign="center">The canonical Port of the server serving the request</td></tr><tr><td align="left" valign="center"><code>%q</code></td><td align="left" valign="center">The query string (prepended with a ? if a query string exists, otherwise an empty string)</td></tr><tr><td align="left" valign="center"><code>%r</code></td><td align="left" valign="center">First line of request</td></tr><tr><td align="left" valign="center"><code>%s</code></td><td align="left" valign="center">Request HTTP status code</td></tr><tr><td align="left" valign="center"><code>%T</code></td><td align="left" valign="center">Request duration, elapsed time to handle request in seconds '.' micro seconds</td></tr><tr><td align="left" valign="center"><code>%U</code></td><td align="left" valign="center">The URL path requested, not including any query string.</td></tr><tr><td align="left" valign="center"><code>%v</code></td><td align="left" valign="center">The canonical ServerName of the server serving the request</td></tr><tr><td align="left" valign="center"><code>%V</code></td><td align="left" valign="center">The server name according to the UseCanonicalName setting</td></tr><tr><td align="left" valign="center"><code>%w</code></td><td align="left" valign="center">Tomcat worker name</td></tr><tr><td align="left" valign="center"><code>%R</code></td><td align="left" valign="center">Real worker name</td></tr></table>
<div class="example"><pre>
JkRequestLogFormat "%w %V %T"
</pre></div>
<br>
<br>
</p>
</blockquote></td></tr></table>
<table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Forwarding"><strong>Forwarding</strong></a></font></td></tr><tr><td><blockquote>
<p>
The directive JkOptions allow you to set many forwarding options which will enable (+)
or disable (-) following option. Without any leading signs, options will be enabled.
<br>
<br>
</p>
<p>
The four following options <b>+ForwardURIxxx</b> are mutually exclusive.
Exactly one of them is required, a negative sign prefix is not allowed with them.
The default value is "ForwardURIProxy" since version 1.2.24.
It was "ForwardURICompatUnparsed" in version 1.2.23 and
"ForwardURICompat" until version 1.2.22.
You can turn the default off by switching on one of the other two options.
You should leave this at it's default value, unless you have a very good
reason to change it.
<br>
<br>
</p>
<p>
All options are inherited from the global server to virtual hosts.
Options that support enabling (plus options) and disabling (minus options),
are inherited in the following way:
<br>
<br>
options(vhost) = plus_options(global) - minus_options(global) + plus_options(vhost) - minus_options(vhost)
<br>
<br>
</p>
<p>
Using JkOptions <b>ForwardURIProxy</b>, the forwarded URI
will be partially reencoded after processing inside Apache httpd and
before forwarding to Tomcat. This will be compatible with local
URL manipulation by mod_rewrite and with URL encoded session ids.
<div class="example"><pre>
JkOptions +ForwardURIProxy
</pre></div>
<br>
<br>
</p>
<p>
Using JkOptions <b>ForwardURICompatUnparsed</b>, the forwarded URI
will be unparsed. It's spec compliant and secure.
It will always forward the original request URI, so rewriting
URIs with mod_rewrite and then forwarding the rewritten URI
will not work.
<div class="example"><pre>
JkOptions +ForwardURICompatUnparsed
</pre></div>
<br>
<br>
</p>
<p>
Using JkOptions <b>ForwardURICompat</b>, the forwarded URI will
be decoded by Apache httpd. Encoded characters will be decoded and
explicit path components like ".." will already be resolved.
This is less spec compliant and is <b>not safe</b> if you are using
prefix JkMount. This option will allow to rewrite URIs with
mod_rewrite before forwarding.
<div class="example"><pre>
JkOptions +ForwardURICompat
</pre></div>
<br>
<br>
</p>
<p>
Using JkOptions <b>ForwardURIEscaped</b>, the forwarded URI will
be the encoded form of the URI used by ForwardURICompat.
Explicit path components like ".." will already be resolved.
This will not work in combination with URL encoded session IDs,
but it will allow to rewrite URIs with mod_rewrite before forwarding.
<div class="example"><pre>
JkOptions +ForwardURIEscaped
</pre></div>
<br>
<br>
</p>
<p>
JkOptions <b>RejectUnsafeURI</b> will block all
URLs, which contain percent signs '%' or backslashes '\'
after decoding.
<br>
<br>
</p>
<p>
Most web apps do not use such URLs. Using the option RejectUnsafeURI, you
can block several well known URL encoding attacks. By default, this option
is not set.
</p>
<p>
You can also realise such a check with mod_rewrite, which is more powerful
but also slightly more complicated.
<div class="example"><pre>
JkOptions +RejectUnsafeURI
</pre></div>
<br>
<br>
</p>
<p>
JkOptions <b>CollapseSlashesAll</b> will collapse multiple
adjacent slashes in request URLs before looking for mount or unmount
matches.
<div class="example"><pre>
JkOptions +CollapseSlashesAll
</pre></div>
<br>
<br>
</p>
<p>
JkOptions <b>CollapseSlashesUnmount</b> will collapse multiple
adjacent slashes in request URLs only before looking for unmount
matches. This is the default value.
<div class="example"><pre>
JkOptions +CollapseSlashesUnmount
</pre></div>
<br>
<br>
</p>
<p>
JkOptions <b>CollapseSlashesNone</b> will never collapse multiple
adjacent slashes in request URLs before looking for mount or unmount
matches. Using this value might make you vulnerable for attacks
bypassing your unmount rules.
<div class="example"><pre>
JkOptions +CollapseSlashesNone
</pre></div>
<br>
<br>
</p>
<p>
JkOptions <b>ForwardDirectories</b> is used in conjunction with <b>DirectoryIndex</b>
directive of Apache web server. As such mod_dir should be available to Apache,
statically or dynamically (DSO)
<br>
<br>
</p>
<p>
When DirectoryIndex is configured, Apache will create sub-requests for
each of the local-url's specified in the directive, to determine if there is a
local file that matches (this is done by stat-ing the file).
</p>
<p>
If ForwardDirectories is set to <b>false</b> (default) and Apache doesn't find any
files that match, Apache will serve the content of the directory (if directive
Options specifies Indexes for that directory) or a <b class="code">403 Forbidden</b> response (if
directive Options doesn't specify Indexes for that directory).
</p>
<p>
If ForwardDirectories is set to <b>true</b> and Apache doesn't find any files that
match, the request will be forwarded to Tomcat for resolution. This is used in
cases when Apache cannot see the index files on the file system for various
reasons: Tomcat is running on a different machine, the JSP file has been
precompiled etc.
</p>
<p>Note that locally visible files will take precedence over the
ones visible only to Tomcat (i.e. if Apache can see the file, that's the one
that's going to get served). This is important if there is more then one type of
file that Tomcat normally serves - for instance Velocity pages and JSP pages.
<div class="example"><pre>
JkOptions +ForwardDirectories
</pre></div>
<br>
<br>
</p>
<p>
Setting JkOptions <b>ForwardLocalAddress</b>, you ask mod_jk to send the local address,
of the Apache web server instead remote client address. This can be used by
Tomcat remote address valve for allowing connections only from registered Apache
web servers.
<div class="example"><pre>
JkOptions +ForwardLocalAddress
</pre></div>
<br>
<br>
</p>
<p>
Setting JkOptions <b>ForwardPhysicalAddress</b>, you ask mod_jk to send the
physical peer TCP IP address as the client address. By default mod_jk
uses the logical address as provided by the web server. For example the module
mod_remoteip sets the logical IP address to the client IP forwarded by proxies
in the <b class="code">X-Forwarded-For</b> header.
<div class="example"><pre>
JkOptions +ForwardPhysicalAddress
</pre></div>
<br>
<br>
</p>
<p>
JkOptions <b>FlushPackets</b>, you ask mod_jk to flush Apache's connection
buffer after each AJP packet chunk received from Tomcat. This option can have
a strong performance penalty for Apache and Tomcat as writes are performed
more often than would normally be required (ie: at the end of each
response).
<div class="example"><pre>
JkOptions +FlushPackets
</pre></div>
<br>
<br>
</p>
<p>
JkOptions <b>FlushHeader</b>, you ask mod_jk to flush Apache's connection
buffer after the response headers have been received from Tomcat.
<div class="example"><pre>
JkOptions +FlushHeader
</pre></div>
<br>
<br>
</p>
<p>
JkOptions <b>DisableReuse</b>, you ask mod_jk to close connections immediately
after their use. Normally mod_jk uses persistent connections and pools idle
connections to reuse them, when new requests have to be sent to Tomcat.
</p>
<p>
Using this option will have a strong performance penalty for Apache and Tomcat.
Use this only as a last resort in case of unfixable network problems.
If a firewall between Apache and Tomcat silently kills idle connections,
try to use the worker attribute socket_keepalive in combination with an appropriate
TCP keepalive value in your OS.
<div class="example"><pre>
JkOptions +DisableReuse
</pre></div>
<br>
<br>
</p>
<p>
JkOptions <b>ForwardKeySize</b>, you ask mod_jk, when using ajp13, to forward also the SSL Key Size as
required by Servlet API 2.3.
This flag shouldn't be set when servlet engine is Tomcat 3.2.x (on by default).
<div class="example"><pre>
JkOptions +ForwardKeySize
</pre></div>
<br>
<br>
</p>
<p>
JkOptions <b>ForwardSSLCertChain</b>, you ask mod_jk, when using ajp13,
to forward SSL certificate chain (off by default).
Mod_jk only passes the <b class="code">SSL_CLIENT_CERT</b> to the AJP connector. This is not a
problem with self-signed certificates or certificates directly signed by the
root CA certificate. However, there's a large number of certificates signed by
an intermediate CA certificate, where this is a significant problem: A servlet
will not have the possibility to validate the client certificate on its own. The
bug would be fixed by passing on the <b class="code">SSL_CLIENT_CERT_CHAIN</b> to Tomcat via the AJP connector.
<br>
This directive exists only since version 1.2.22.
<div class="example"><pre>
JkOptions +ForwardSSLCertChain
</pre></div>
<br>
<br>
</p>
<p>
The directive <b>JkEnvVar</b> allows you to forward environment variables
from Apache server to Tomcat engine.
You can add a default value as a second parameter to the directive.
If the default value is not given explicitly, the variable
will only be send, if it is set during runtime.
<br>
The variables can be retrieved on the Tomcat side as request attributes
via request.getAttribute(attributeName).
Note that the variables send via JkEnvVar will not be listed
in request.getAttributeNames().
<br>
<br>
The variables are inherited from the global server to virtual hosts.
<div class="example"><pre>
JkEnvVar SSL_CLIENT_V_START undefined
</pre></div>
<br>
<br>
</p>
</blockquote></td></tr></table>
<table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Assigning URLs to Tomcat"><strong>Assigning URLs to Tomcat</strong></a></font></td></tr><tr><td><blockquote>
<p>
If you have created a custom or local version of mod_jk.conf-local as noted above,
you can change settings such as the workers or URL prefix.
</p>
<p>
<b>JkMount</b> directive assign specific URLs to Tomcat.
In general the structure of a JkMount directive is:
</p>
<div class="example"><pre>
JkMount [URL prefix] [Worker name]
</pre></div>
<div class="example"><pre>
# send all requests ending in .jsp to worker1
JkMount /*.jsp worker1
# send all requests ending /servlet to worker1
JkMount /*/servlet/ worker1
# send all requests jsp requests to files located in /otherworker will go worker2
JkMount /otherworker/*.jsp worker2
</pre></div>
<p>
You can use the JkMount directive at the top level or inside <VirtualHost>
sections of your httpd.conf file.
</p>
<p><b>JkUnMount</b> directive acts as an opposite to JkMount and blocks access
to a particular URL. The purpose is to be able to filter out the particular content
types from mounted context. The following example mounts /servlet/*
context, but all .gif files that belongs to that context are not served.
</p>
<div class="example"><pre>
# send all requests ending with /servlet to worker1
JkMount /servlet/* worker1
# do not send requests ending with .gif to worker1
JkUnMount /servlet/*.gif worker1
</pre></div>
<p>
JkUnMount takes precedence over JkMount directives, meaning that the JK
will first try to mount and then checks, if there is an exclusion defined by a
JkUnMount. A JkUnMount overrides a JkMount only, if the worker names in the
JkMount and in the JkUnMount are the same.
</p>
<p>
The following example will block all .gif files although there is a JkMount for them:
</p>
<div class="example"><pre>
# do not send requests ending with .gif to worker1
JkUnMount /*.gif worker1
# The .gif files will not be mounted cause JkUnMount takes
# precedence over JkMount directive
JkMount /servlet/*.gif worker1
</pre></div>
<p>
Starting with version 1.2.26 of JK you can apply a JkUnMount to any worker,
by using the star character '*' as the worker name in the JkUnMount.
More complex patterns in JkUnMount worker names are not allowed.
</p>
<div class="example"><pre>
# Mapping the webapps myapp1 and myapp2:
/myapp1/*=worker1
/myapp2/*=worker2
# Exclude the all subdirectories static for all workers:
!/*/static/*=*
# Exclude some suffixes for all workers:
!*.html=*
</pre></div>
<p>
<b>JkAutoAlias</b> directive automatically <b>Alias</b> webapp context directories into
the Apache document space. It enables Apache to serve a static context while Tomcat
serving dynamic context. This directive is used for convenience so that you don't
have to put an apache Alias directive for each application directory inside Tomcat's
webapp directory. For security reasons it is strongly recommended that JkMount
is used to pass all requests to Tomcat by default and JkUnMount is used to
explicitly exclude static content to be served by httpd. It should also be noted
that content served by httpd will bypass any security constraints defined in the
application's web.xml.
</p>
<div class="example"><pre>
# enter the full path to the tomcat webapps directory
JkAutoAlias /opt/tomtact/webapps
</pre></div>
<p>The following example shows how to serve a dynamic context by
Tomcat and static using Apache. The webapps directory has to
be accessible by apache.</p>
<div class="example"><pre>
# enter the full path to the tomcat webapps directory
JkAutoAlias /opt/tomtact/webapps
# Mount 'servlets-examples' directory. It's physical location
# is assumed to be in the /opt/tomtact/webapps/servlets-examples
# ajp13w is a worker defined in the workers.properties
JkMount /servlets-examples/* ajp13w
# Unmount desired static content from servlets-examples webapp.
# This content will be served by the httpd directly.
JkUnMount /servlets-examples/*.gif ajp13w
JkUnMount /servlets-examples/*.jpg ajp13w
</pre></div>
<p>Note that you can have a single JkAutoAlias directive per virtual
host inside your httpd.conf
</p>
<p>
<b>JkWorkerProperty</b> is a new directive available from JK 1.2.7
version. It is a convenient method for setting directives that are
usually set inside <b>workers.propeties</b> file. The parameter for
that directive is raw line from workers.properties file.
</p>
<div class="example"><pre>
# Just like workers.properties but exact line is prefixed
# with JkWorkerProperty
# Minimal jk configuration
JkWorkerProperty worker.list=ajp13w
JkWorkerProperty worker.ajp13w.type=ajp13
JkWorkerProperty worker.ajp13w.host=localhost
JkWorkerProperty worker.ajp13w.port=8009
</pre></div>
<p>
<b>JkMountFile</b> is a new directive available from JK 1.2.9
version. It is used for dynamic updates of mount points at runtime.
When the mount file is changed, JK will reload it's content.
</p>
<div class="example"><pre>
# Load mount points
JkMountFile conf/uriworkermap.properties
</pre></div>
<p>If the mount point uri starts with an exclamation mark '!'
it defines an exclusion in the same way JkUnMount does.
If the mount point uri starts with minus sign '-'
the mount point will only be disabled. A disabled mount can be reenabled
by deleting the minus sign and waiting for the JkMountFile to reload.
An exclusion can be disabled by prefixing it with a minus sign.
</p>
<div class="example"><pre>
# Sample uriworkermap.properties file
/servlets-examples/*=ajp13w
# Do not map .jpeg files
!/servlets-examples/*.jpeg=ajp13w
# Make jsp examples initially disabled
-/jsp-examples/*=ajp13w
</pre></div>
<p>At run time you can change the content of this file. For example
removing minus signs will enable the previously disabled uri mappings.
You can add any number of new entries at runtime that reflects the newly deployed
applications. Apache will reload the file and update the mount
points within 60 second interval.
</p>
<p>
There is no way to delete entries by dynamic reloading, but you can disable or
exclude mappings.
<br>
<br>
</p>
</blockquote></td></tr></table>
<table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Using SetHandler and Environment Variables"><strong>Using SetHandler and Environment Variables</strong></a></font></td></tr><tr><td><blockquote>
<p>
Alternatively to the mod_jk specific directives, you can also use
SetHandler and environment variables to control, which requests
are being forwarded via which worker. This gives you more flexibility,
but the results might be more difficult to understand. If you mix both
ways of defining the forwards, in general to mod_jk directives will win.
</p>
<p>
<b>SetHandler jakarta-servlet</b> forces requests to be handled by mod_jk.
If you neither specify any workers via JkMount and the related directives,
not via the environment variable described below,
the first worker in the list of all worker will be chosen. You can use SetHandler
for example in Location blocks or with Apache 2.2 and later also in RewriteRule.
</p>
<p>
In order to control the worker using <b>SetEnvIf</b> or <b>RewriteRule</b>
for more complex rules, you can set the environment variable <b>JK_WORKER_NAME</b>
to the name of your chosen target worker. This enables you to decide on
the chosen worker in a more flexible way, including dependencies on cookie values.
This feature has been added in version 1.2.19 of mod_jk. Furthermore you might
append rule extensions to the worker name. The extensions are separated from the
worker name by a semicolon ";" using the same syntax as in the
uriworkermap.properties file. Supporting rule extensions in the worker name has
been added in version 1.2.33.
</p>
<p>
In order to use another variable than <b>JK_WORKER_NAME</b>, you can set the name
of this variable via the <b>JkWorkerIndicator</b> directive.
</p>
<p>
You can also define exclusions from mod_jk forwards by setting the environment
variable <b>no-jk</b>.
</p>
<div class="example"><pre>
# Automatically map all encoded urls
<Location *;jsessionid=>
SetHandler jakarta-servlet
SetEnv JK_WORKER_NAME my_worker
</Location>
# Map all subdirs to workers via naming rule
# and exclude static content.
<Location /apps/>
SetHandler jakarta-servlet
SetEnvIf REQUEST_URI ^/apps/([^/]*)/ JK_WORKER_NAME=$1
SetEnvIf REQUEST_URI ^/apps/([^/]*)/static no-jk
</Location>
</pre></div>
</blockquote></td></tr></table>
<table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td bgcolor="#828DA6"><font color="#ffffff" face="arial,helvetica.sanserif"><a name="Advanced Environment Variables"><strong>Advanced Environment Variables</strong></a></font></td></tr><tr><td><blockquote>
<p>
Environment variables allow to overwrite the default behaviour
of mod_jk depending on request properties like e.g. the request URI,
header values or cookie. This can be done using the <b>SetEnvIf</b> or
<b>RewriteRule</b> directives.
</p>
<p>
The environment variable
<b>JK_ROUTE</b> can be set to explicitely choose a member of a
load balancer worker. The value must be equal to the
route attribute of the member, or if that attribute is not
used, equal to the member name. Note that this is only needed if
session IDs and routes are encoded in a non standard way in the
request. Stickyness using the Java Servlet compliant way of encoding
the IDs is supported by default.
This is available since version 1.2.33.
</p>
<p>
The environment variable
<b>JK_REPLY_TIMEOUT</b> can be set to dynamically define a reply timeout.
The value must be given in milliseconds.
This is available since version 1.2.27.
</p>
<p>
The environment variable
<b>JK_STICKY_IGNORE</b> can be set to disable session stickyness
for individual requests. If the variable is set to an empty string
or a nonzero number, session stickyness will be disabled. Setting
it to <b>0</b> will reset to the behaviour defined by the worker
configuration.
This is available since version 1.2.33.
</p>
<p>
This feature can be useful to optimize load balancing when using
cookie based session stickyness. In this case, as long as she keeps
her browser open, any request by a user who started a session will
be send to the same Tomcat instance, even if he left the part of
the application which uses the session. You can for instance
set this environment variable when a user requests a login form
to ensure, that this initial session request is balanced non-sticky.
</p>
<p>
The environment variable
<b>JK_STATELESS</b> can be used to improve load balancing
for the session based balancing methods <b>Session</b> and
<b>Next</b>.
In this case normally any request which does not come with
a session id counts as a new session. This can be problematic,
if for instance static content is retrieved without a session id.
If you set the environment variable <b>JK_STATELESS</b> for a request,
then the request will not count as a new session, even if it does not
come with a session id.
This is available since version 1.2.33.
</p>
<p>
The environment variable
<b>JK_IGNORE_CL</b> can be set to force ignoring the request
Content-Length header (if it exists). mod_jk will then stream
the request body until the web server indicates that the full body
was read. No Content-Length header will be send to the backend.
This is available since version 1.2.41.
</p>
<p>
This feature can be used to make mod_jk compatible with filters
which change the size of the request body. One such filter is
mod_deflate when used to inflate the body of a request with gzip
encoded body. In this case mod_jk will by default forward a truncated
body, because it gets the wrong body size from the web server.
Telling mod_jk to ignore the Content-Length header will result
in streaming all request body data it can read from the web server
to the backend.
</p>
<p>
You should only set the <b>JK_IGNORE_CL</b> environment variables
for requests that actually need it. Unfortunately there's no way
for mod_jk to detect the need automatically.
</p>
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