After building you application, there are five ways to expose it through the concept of a Service. The idea of a service is to provide a stable virtual IP to a group of endpoints (usually pods). The set pods behind a service can change however clients only need the VIP, which does not change. The five types of Services are
ClusterIP: Exposes the service on a cluster-internal IP. Choosing this value makes the service only reachable from within the cluster. This is the default ServiceType
NodePort: Exposes the service on each Node’s IP at a static port (the NodePort). A ClusterIP service, to which the NodePort service will route, is automatically created. You’ll be able to contact the NodePort service, from outside the cluster, by requesting :.
LoadBalancer: Exposes the service externally using a cloud provider’s load balancer. NodePort and ClusterIP services, to which the external load balancer will route, are automatically created.
A ClusterIP exposes the following:
- spec.clusterIp:spec.ports[*].port
You can only access this service while inside the cluster. It is accessible from its spec.clusterIp port. If a spec.ports[*].targetPort is set it will route from the port to the targetPort.
A NodePort exposes the following:
- (NodeIP):spec.ports[*].nodePort
- spec.clusterIp:spec.ports[*].port
If you access this service on a nodePort from the node's external IP, it will route the request to spec.clusterIp:spec.ports[].port, which will in turn route it to your spec.ports[].targetPort, if set
A LoadBalancer exposes the following:
- spec.loadBalancerIp:spec.ports[*].port
- (NodeIP):spec.ports[*].nodePort
- spec.clusterIp:spec.ports[*].port
You can access this service from your loadbalancer's IP address, which routes your request to a nodePort, which in turn routes the request to the clusterIP port. You can access this service as you would a NodePort or a ClusterIP service as well.
If you have a look at the yaml for a loadbalancer, you will notice the clusterIP, nodePort and loadbalancer ip
