Problems setting up a new whitelabel service via CNAME - php

Question

I have a SAAS and am trying to allow other people to use my SAAS in their own domain. So, supposing my site is app.example.com (hosted with Apache and with PHP as the backend language), I want to allow someone to offer my website from, for example, app.anotherwebsite.com.
I already created a CNAME on app.anotherwebsite.com:
app.anotherwebsite.com CNAME app.example.com.
But if I access app.anotherwebsite.com, it loads the default cPanel page on app.anotherwebsite.com/cgi-sys/defaultwebpage.cgi.
I already tried many solutions offered on the web with no luck. Does anyone have any clue how to solve this? Do I have to do something on the example.com server to fix this?
Thanks a lot!

Answer 1

When you create a CNAME and try to make a HTTP request to it, the computer does the follow:
1) Try to discover the IP related to your hostname (in this case, app.anotherwebsite.com), and the CNAME it's an alias to another hostname, that need to point to an IP address;
2) When the computer has the IP address of the hostname, it connect to port 80 (in case of HTTP) or port 443 (in case of HTTPS) and request the page app.anotherwebsite.com;
3) Your HTTP server at the IP address will search it configuration for a virtual host that match app.anotherwebsite.com. If there's no virtual host configured that match the requested hostname, it will serve the default virtual host. At Apache, if there's no explicit declared default virtual host, the first virtual host configured will be elected as default.
In your case, your CPANEL is your default virtual host, and that's why it's displaying it.
So, to make your SASS work at this scenario, you can change your default virtual host to your application or you can add a virtual host with wildcard, like app.*. It'll receive the requested hostname (at PHP, you can access it as $_SERVER["SERVER_NAME"]).
Below is an example code:
<?php
echo "Hello!<br />\n";
echo "<br />\n";
echo "I'm seeing you're requesting the hostname " . $_SERVER["SERVER_NAME"] . "!\n";
?>
Your code can handle this information and serve your client based on that variable.
EDIT:
You can add a virtual server at Apache using this code:
<VirtualHost *:80>
ServerName app.example.com
ServerAlias app.*
DocumentRoot /var/www/SASS
<Directory /var/www/SASS>
Options -Indexes +FollowSymLinks +MultiViews
AllowOverride All
Require all granted
</Directory>
ErrorLog ${APACHE_LOG_DIR}/SASS-error.log
CustomLog ${APACHE_LOG_DIR}/SASS-access.log combined
</VirtualHost>
This Apache virtual host add a new server named app.example.com, and will also match app.* requests.
The server will point to /var/www/SASS as root directory, looking for index.html or index.php (if there's PHP enabled at Apache) file.
The permissions to /var/www/SASS granted with tag <Directory> disallow the automatic creation of index files of directories without index file and allow use of .htaccess.
Also, was created a separated error_log and access_log to log requests matching this entry.
To check your Apache configuration and look for all your virtual hosts, use the following command:
apachectl -t -D DUMP_VHOSTS
This will produce an output like:
VirtualHost configuration:
wildcard NameVirtualHosts and _default_ servers:
*:80 is a NameVirtualHost
default server cpanel.example.com (/etc/httpd/conf/httpd.conf:994)
port 80 namevhost cpanel.example.com (/etc/httpd/conf/httpd.conf:994)
port 80 namevhost app.example.com (/etc/httpd/conf/httpd.conf:1044)
wild alias app.*
Syntax OK