How to set apache into maintenance mode

I found a way to set apache show maintenance page automatically without restart apache. With the following method, we just touch or remove one file, it will turn on or off the maintenance mode. Basically, I learnt from this page: Redirect-Site-to-Maintenance-Page-using-Apache-and-HTAccess

Change httpd.conf

make sure the rewrite module is loaded:

LoadModule rewrite_module modules/mod_rewrite.so

Then add rewrite rule:

DocumentRoot "/opt/root_dir/"
<IfModule mod_rewrite.c>
   RewriteEngine On
   #RewriteCond %{REMOTE_ADDR} !^123\.456\.789\.000
   RewriteCond %{DOCUMENT_ROOT}/maintenance.html -f
   RewriteCond %{DOCUMENT_ROOT}/maintenance.enable -f
   RewriteCond %{SCRIPT_FILENAME} !maintenance.html
   RewriteRule ^.*$ /maintenance.html [R=503,L]
   ErrorDocument 503 /maintenance.html
   Header Set Cache-Control "max-age=0, no-store"
</IfModule>

Then add the maintenance.html page in the DocumentRoot. When the site is under maintenance mode, please touch maintenance.enable file in DocumentRoot. After the site becomes normally, please just remove the maintenance.enable

TIPs: as we used the wsgi in apache, any changes to python file, we need to restart the apache.

Add alias in wsgi conf

add the following line in the conf.d/myproject.conf or conf.d/otherproject.conf:

Alias /maintenance.html /opt/root_dir/maintenance.html

Restart Apache and Demo

restart Apache, it should work. And I already make a demo, here are the config files with path:

httpd.conf -> /opt/root_dir/httpd/conf
application.conf -> /opt/root_dir/httpd/conf.d
maintenance.html -> /opt/root_dir
maintenance.enable -> /opt/root_dir