How to achieve cross-namespace access in k8s?

To achieve cross-access between different namespaces in Kubernetes, you can utilize the following methods:

1. By using Fully Qualified Domain Names (FQDNs), Kubernetes creates domain names for all services within the cluster. Specifying the service name as a Fully Qualified Domain Name allows a Pod in one namespace to access a service in another namespace. For example, to access a service in namespace B from a Pod in namespace A, you can use the FQDN of the service, such as ..svc.cluster.local.
2. Utilize Service Proxy: Kubernetes allows accessing services through a proxy. You can create a service proxy in one namespace, pointing it to a service in another namespace. Then, you can access the target service by accessing the proxy on your local host.
3. Using Ingress: Ingress is a routing mechanism provided by Kubernetes that routes traffic to services in different namespaces using Ingress resources. By specifying the target service’s namespace and service name in the Ingress rules, cross-namespace access can be achieved.
4. Utilize network policies: Kubernetes network policies can establish rules for controlling network access between Pods. By creating a network policy in the target namespace, it allows Pods from other namespaces to access services within the target namespace.

It is important to note that accessing across namespaces may involve considerations of security and permission management. When setting up cross-namespace access, appropriate authentication and authorization mechanisms should be used to ensure the security of the access.