This is a web application for ApisCP.

cd /usr/local/apnscp
mkdir -p config/custom/webapps
git clone https://github.com/LithiumHosting/apiscp-webapp-whmcs config/custom/webapps/whmcs
./composer dump-autoload -o

Edit config/custom/boot.php, create if not exists:

<?php
	\a23r::registerModule('whmcs', \lithiumhosting\whmcs\Whmcs_Module::class);
	\Module\Support\Webapps::registerApplication('whmcs', \lithiumhosting\whmcs\Handler::class);

Then restart ApisCP.

systemctl restart apiscp

Voila!

To install WHMCS to whmcs.domain.test for the domain domain.test run the following:

cpcmd -d domain.test whmcs:install whmcs.domain.test '' '[license_key:DEV123XYZ]'

Or to install WHMCS to a subfolder of whmcs on the domain domain.test run the following:

cpcmd -d domain.test whmcs:install domain.test 'whmcs' '[license_key:DEV123XYZ]'

WHMCS installation requires a License Key, be sure to pass it as license_key.

cpcmd -d domain.test whmcs:uninstall domain.test 'whmcs' all

passing "all" as the 3rd parameter will remove the database and files

All third-party documentation is available via docs.apiscp.com.