title: Apache returning null for environment variables in header
body: <p>I am trying to troubleshoot my apache test site right now.  I need to have the mod_rewrite variables returned in the header so that I can see what is going on.  However, when I try to set them in the header, I get null</p>
  <p>Server version: Apache/2.4.51 (Fedora)</p>
  <p><strong>config</strong></p>
  <pre><code>&lt;VirtualHost mysite.local:80&gt;
    ServerName mysite
    DocumentRoot /var/www/html/mysite
    Header always set TestHeader &quot;%{SERVER_NAME}e&quot;
  </code></pre>
  <p><strong>output from curl</strong></p>
  <p><code>curl -I http://mysite.local/index.html</code></p>
  <pre><code>HTTP/1.1 200 OK
  Date: Tue, 01 Feb 2022 02:05:42 GMT
  Server: Apache/2.4.51 (Fedora)
  TestHeader: (null)
  Last-Modified: Tue, 25 Jan 2022 19:37:28 GMT
  ETag: &quot;15-5d66d372009de&quot;
  Accept-Ranges: bytes
  Content-Length: 21
  Content-Type: text/html; charset=UTF-8
  </code></pre>
  <p>Also, mod_headers and mod_rewrite are enabled</p>
  <pre><code>$ grep -R 'mod_rewrite' conf.modules.d/
  conf.modules.d/00-base.conf:LoadModule rewrite_module modules/mod_rewrite.so
  </code></pre>
  <pre><code>$ grep -R 'mod_headers' conf.modules.d/
  conf.modules.d/00-base.conf:LoadModule headers_module modules/mod_headers.so
  </code></pre>
  <p>Am I missing some setting or configuration?</p>