httpd 2.4.1 and later) prevents this.</p>
<p>The optional <var>interpolate</var> keyword, in combination with
- <code class="directive">ProxyPassInterpolateEnv</code>, causes the ProxyPass
+ <code class="directive"><a href="#proxypassinterpolateenv">ProxyPassInterpolateEnv</a></code>, causes the ProxyPass
to interpolate environment variables, using the syntax
<var>${VARNAME}</var>. Note that many of the standard CGI-derived
environment variables will not exist when this interpolation happens,
so you may still have to resort to <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>
- for complex rules. Also note that interpolation is not supported
- within the scheme/hostname/port portion of a URL. Dynamic determination of
+ for complex rules. Also note that interpolation is supported
+ within the scheme/hostname/port portion of a URL only for variables that
+ are available when the directive is parsed
+ (like <code class="directive"><a href="../mod/core.html#define">Define</a></code>). Dynamic determination of
those fields can be accomplished with <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>.
The following example describes how to use <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code>
to dynamically set the scheme to http or https:</p>
and causes them to substitute the value of an environment
variable <code>varname</code> for the string <code>${varname}</code>
in configuration directives if the <var>interpolate</var> option is set.</p>
- <p>The scheme/hostname/port portion of <code class="directive">ProxyPass</code> cannot
- contain variables, please consider using <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> instead.</p>
- <p>Keep this turned off (for server performance) unless you need it!
+ <p>The scheme/hostname/port portion of <code class="directive">ProxyPass</code> may
+ contain variables, but only the ones available when the directive is parsed
+ (for example, using <code class="directive"><a href="../mod/core.html#define">Define</a></code>).
+ For all the other use cases, please consider using
+ <code class="module"><a href="../mod/mod_rewrite.html">mod_rewrite</a></code> instead.</p>
+ <div class="warning"><h3>Performance warning</h3>
+ <p>Keep this turned off unless you need it!
Adding variables to <code class="directive">ProxyPass</code> for example may lead to
- using the default mod_proxy's workers configured (that don't allow any fine
+ the use of the default mod_proxy's workers configured (that don't allow any fine
tuning like connections reuse, etc..).</p>
+ </div>
</div>
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