In most cases, the cluster IP and node IP addresses of a Kubernetes or OpenShift cluster are internal and not directly accessible from outside the cluster's network. These internal IPs are typically assigned from private IP address ranges defined by RFC 1918 (e.g., 10.0.0.0/8, 172.16.0.0/12, or 192.168.0.0/16) and are used for communication between the nodes and components within the cluster.
Here's a breakdown of these terms:
1. **Cluster IP**: This is an internal IP address assigned to a Kubernetes service within the cluster. It allows other components within the cluster to communicate with the service. Cluster IPs are typically not accessible from outside the cluster without going through a service proxy or load balancer.
2. **Node IP**: Each node in the Kubernetes or OpenShift cluster has its own internal IP address. These node IPs are used for intra-cluster communication between nodes, as well as for communication between nodes and cluster components. Node IPs are also generally not directly accessible from outside the cluster's network.
To make services or applications running in the cluster accessible from outside, Kubernetes or OpenShift clusters often use load balancers, Ingress controllers, or NodePort services to expose services to external traffic. These external access mechanisms typically involve exposing services on publicly accessible IP addresses and ports, often through a combination of network configurations and cloud provider services.
It's essential to configure network policies and security controls to ensure that only authorized traffic can access services exposed externally from the cluster, maintaining the security and integrity of the cluster environment.
