Google Cloud Armor helps to protect applications from DDoS attacks and web application firewall (WAF) threats like XSS and SQLi. To use Google Cloud Armor security policies, certain requirements must be met:

External Load Balancers: Google Cloud Armor is specifically designed to work with external HTTP(S) load balancers, which handle traffic at the edge of the Google Cloud network. This type of load balancer provides a global frontend that can distribute traffic to various backends.

Load Balancing Scheme: The backend service associated with the Google Cloud Armor policy must have an EXTERNAL load balancing scheme. This scheme allows the service to accept traffic from outside the Google Cloud network, which is necessary for applying security policies effectively at the network edge.

These requirements ensure that Google Cloud Armor can inspect and filter incoming traffic before it reaches your web application's backend services, providing an additional layer of security against common web vulnerabilities.

References

Google Cloud Armor Documentation

External HTTP(S) Load Balancing Overview