How to fix Magento 2.0 Index Management stuck at processing state?
There's no var/lock to delete inside Magento 2 root directory, so old ways to fix this are obsolete.
Forcing with these new CLI didn't work either:
sudo -u www-data php /var/www/html/magento2/bin/magento cache:flush
sudo -u www-data php /var/www/html/magento2/bin/magento indexer:reindex