Red Hat build of MicroShift

Extending the port range for NodePort services

The serviceNodePortRange setting extends the port range available to NodePort services. This option is useful when specific standard ports under the 30000-32767 range need to be exposed. For example, if your device needs to expose the 1883/tcp MQ Telemetry Transport (MQTT) port on the network because client devices cannot use a different port.

NodePorts can overlap with system ports, causing a malfunction of the system or MicroShift.

Consider the following when configuring the NodePort service ranges:

Do not create any NodePort service without an explicit nodePort selection. When an explicit nodePort is not specified, the port is assigned randomly by the kube-apiserver and cannot be predicted.
Do not create any NodePort service for any system service port, MicroShift port, or other services you expose on your device HostNetwork.

Table one specifies ports to avoid when extending the port range:

Table 5. Ports to avoid.
Port	Description
22/tcp	SSH port
80/tcp	OpenShift Router HTTP endpoint
443/tcp	OpenShift Router HTTPS endpoint
1936/tcp	Metrics service for the openshift-router, not exposed today
2379/tcp	etcd port
2380/tcp	etcd port
6443	Kubernetes API
8445/tcp	openshift-route-controller-manager
9537/tcp	cri-o metrics
10250/tcp	kubelet
10248/tcp	kubelet healthz port
10259/tcp	kube scheduler