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Chapter 1. How configuration tools work

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A YAML file customizes Red Hat build of MicroShift instances with your preferences, settings, and parameters.

1.1. Using a YAML configuration file

Red Hat build of MicroShift searches for a configuration file in the user-specific directory, ~/.microshift/config.yaml, then the system-wide /etc/microshift/config.yaml directory. You must create the configuration file and specify any settings that should override the defaults before starting Red Hat build of MicroShift.

1.1.1. Default settings

If you do not create a config.yaml file, the default values are used. The following example configuration contains the default settings. You must change any settings that should override the defaults before starting Red Hat build of MicroShift.

Default YAML file example

dns:
  baseDomain: microshift.example.com 1
network:
  clusterNetwork:
    - cidr: 10.42.0.0/16 2
  serviceNetwork:
    - 10.43.0.0/16 3
  serviceNodePortRange: 30000-32767 4
node:
  hostnameOverride: "" 5
  nodeIP: "" 6
apiServer:
  subjectAltNames: [] 7
debugging:
  logLevel: "Normal" 8

1
Base domain of the cluster. All managed DNS records will be subdomains of this base.
2
A block of IP addresses from which Pod IP addresses are allocated.
3
A block of virtual IP addresses for Kubernetes services.
4
The port range allowed for Kubernetes services of type NodePort.
5
The name of the node. The default value is the hostname.
6
The IP address of the node. The default value is the IP address of the default route.
7
Subject Alternative Names for API server certificates.
8
Log verbosity. Valid values for this field are Normal, Debug, Trace, or TraceAll.
Important

Restart Red Hat build of MicroShift after changing any configuration settings to have them take effect. Red Hat build of MicroShift reads the configuration file only on start.

1.2. 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.

Important

NodePorts can overlap with system ports, causing a malfunction of the system or Red Hat build of 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, Red Hat build of MicroShift port, or other services you expose on your device HostNetwork.

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

    Table 1.1. Ports to avoid.
    PortDescription

    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

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