Docs: Add an example for Apache VHost configuration into Advanced Topics

doc/20-Advanced-Topics.md

@@ -1,7 +1,88 @@
 # Advanced Topics <a id="advanced-topics"></a>
 
-This chapter contains advanced Icinga Web 2 topics such as source installation
-or automation hints.
+This chapter provides details for advanced Icinga Web 2 topics.
+
+* [VirtualHost configuration](20-Advanced-Topics.md#virtualhost-configuration)
+* [Source installation](20-Advanced-Topics.md#installing-from-source)
+* [Automated setup](20-Advanced-Topics.md#web-setup-automation)
+
+## VirtualHost Configuration <a id="virtualhost-configuration"></a>
+
+This describes how to run Icinga Web 2 on your FQDN's `/` entry point without
+any redirect to `/icingaweb2`.
+
+### VirtualHost Configuration for Apache <a id="virtualhost-configuration-apache"></a>
+
+Use the setup CLI commands to generate the default Apache configuration which serves
+Icinga Web 2 underneath `/icingaweb2`.
+
+The next steps are to create the VirtualHost configuration:
+
+* Copy the `<Directory "/usr/share/icingaweb2/public">` into the main VHost configuration. Don't forget to correct the indent.
+* Set the `DocumentRoot` variable to look into `/usr/share/icingaweb2/public`
+* Modify the `RewriteBase` variable to use `/` instead of `/icingaweb2`
+
+Example on RHEL/CentOS:
+
+```
+vim /etc/httpd/conf.d/web.icinga.com.conf
+
+<VirtualHost *:80>
+  ServerName web.icinga.com
+
+  ## Vhost docroot
+  # modified for Icinga Web 2
+  DocumentRoot "/usr/share/icingaweb2/public"
+
+  ## Rewrite rules
+  RewriteEngine On
+
+  <Directory "/usr/share/icingaweb2/public">
+      Options SymLinksIfOwnerMatch
+      AllowOverride None
+
+      <IfModule mod_authz_core.c>
+          # Apache 2.4
+          <RequireAll>
+              Require all granted
+          </RequireAll>
+      </IfModule>
+
+      <IfModule !mod_authz_core.c>
+          # Apache 2.2
+          Order allow,deny
+          Allow from all
+      </IfModule>
+
+      SetEnv ICINGAWEB_CONFIGDIR "/etc/icingaweb2"
+
+      EnableSendfile Off
+
+      <IfModule mod_rewrite.c>
+          RewriteEngine on
+          # modified base
+          RewriteBase /
+          RewriteCond %{REQUEST_FILENAME} -s [OR]
+          RewriteCond %{REQUEST_FILENAME} -l [OR]
+          RewriteCond %{REQUEST_FILENAME} -d
+          RewriteRule ^.*$ - [NC,L]
+          RewriteRule ^.*$ index.php [NC,L]
+      </IfModule>
+
+      <IfModule !mod_rewrite.c>
+          DirectoryIndex error_norewrite.html
+          ErrorDocument 404 /error_norewrite.html
+      </IfModule>
+  </Directory>
+</VirtualHost>
+```
+
+Reload Apache and open the FQDN in your web browser.
+
+```
+systemctl reload httpd
+```
+
 
 ## Installing Icinga Web 2 from Source <a id="installing-from-source"></a>
 
@@ -312,7 +393,7 @@ password = "api"
 
 Finally visit Icinga Web 2 in your browser to login as `icingaadmin` user: `/icingaweb2`.
 
-## Automating the Installation of Icinga Web 2
+## Automating the Installation of Icinga Web 2 <a id="web-setup-automation"></a>
 
 If you are automating the installation of Icinga Web 2, you may want to skip the wizard and do things yourself.
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