CORS (resource sharing between different sources) is browser technology that allows a web page to access resources from another domain.
To enable CORS in Apache2, you must first activate the headers module, in Ubuntu Server, you can do this with the command:
sudo a2enmod headers
Then you need to enable the configuration for a specific site in the VirtualHost section or in the .htaccess file by adding the following line:
Header set Access-Control-Allow-Origin "*"
You can check for example on this site:
If HAProxy is used on the server, then you also need to make the settings, add one line at the end of the frontend section:
capture request header origin len 128
And the second at the end of the backend section:
http-response set-header Access-Control-Allow-Origin %[capture.req.hdr(0)]