What is the best method to ensure all traffic within a Google Kubernetes Engine cluster is encrypted?

Installing Istio and enabling mutual TLS (mTLS) for application traffic is the best method to ensure that all traffic within a Google Kubernetes Engine (GKE) cluster is encrypted. Istio is a service mesh that provides advanced traffic management, security, and observability for applications running in a Kubernetes environment.

By enabling mTLS, Istio ensures that all services within the cluster communicate with each other over encrypted channels. This means that, not only is the data transferred between services encrypted, but the identities of the communicating services are also verified, which prevents unauthorized access. mTLS establishes secure connections between microservices by automatically managing the certificates required for encryption, thereby enhancing security significantly without the need for manual intervention by developers.

While other options may assist in managing network traffic and security, they do not provide the same level of built-in encryption and identity assurance that mTLS does. For example, Network Policies can help control traffic flow but do not encrypt it. Defining Trusted Network ranges is about managing IP addresses rather than encryption. Requesting SSL Certificates from Let's Encrypt helps with securing external traffic but does not address the encryption of service-to-service communication within the cluster. Thus, enabling mTLS through Istio provides a comprehensive solution for securing traffic within GKE