Nothing. The app is based on Node.js so you won't need apache or any other PHP services. If you already have a VPS running other services you can still use this app if you have root access to install Docker.
This error happens when your app application id or fingerprint doesn't match what has been entered on the firebase console. Make sure those two are correct and generate a new
google-services.jsonand try again in a few minutes.
This could happen if the firewall is not open for the ports used by the app for external connections for example you can open port 8080 using these commands:
sudo firewall-cmd --zone=public --add-port=4000/tcp --permanent
sudo firewall-cmd --zone=public --add-port=4001/tcp --permanent
sudo firewall-cmd --zone=public --add-port=4002/tcp --permanent
sudo firewall-cmd --zone=public --add-port=4003/tcp --permanent
sudo firewall-cmd --reload
sudo ufw allow 4000
sudo ufw allow 4001
sudo ufw allow 4002
sudo ufw allow 4003
Most of the time it is due to a misconfiguration in Maps API key provided for Backend App. Check it's own section for having correct configuration in terms of Billing, Library and restrictions.
Most probable reason for this is system reboot. Some hostings might occasionally reboot their servers. In case of reboot following command would restart the app services
docker-compose up -d