Chapter 8. Configuring network settings for fully disconnected hosts

Procedure

1. Stop the MicroShift service by running the following command:

   $ sudo systemctl stop microshift

2. Stop the kubepods.slice systemd unit by running the following command:

   $ sudo systemctl stop kubepods.slice

3. MicroShift installs a helper script to undo network changes made by OVN-K. Run the cleanup script by entering the following command:

   $ sudo /usr/bin/microshift-cleanup-data --ovn

Procedure

1. Add a fake IP address to the loopback interface by running the following command:

   $ IP="10.44.0.1" 1
   $ sudo nmcli con add type loopback con-name stable-microshift ifname lo ip4 ${IP}/32

   1

   The fake IP address used in this example is “10.44.0.1”.

   Note

   Any valid IP works if it avoids both internal MicroShift and potential future external IP conflicts. This can be any subnet that does not collide with the MicroShift node subnet or is be accessed by other services on the device.

2. Configure the DNS interface to use the local name server by setting modifying the settings to ignore automatic DNS and reset it to the local name server:

   1. Bypass the automatic DNS by running the following command:

      $ sudo nmcli conn modify stable-microshift ipv4.ignore-auto-dns yes

   2. Point the DNS interface to use the local name server:

      $ sudo nmcli conn modify stable-microshift ipv4.dns "10.44.1.1"

3. Get the hostname of the device by running the following command:

   $ NAME="$(hostnamectl hostname)"

4. Add an entry for the hostname of the node in the /etc/hosts file by running the following command:

   $ echo "$IP $NAME" | sudo tee -a /etc/hosts >/dev/null

5. Update the MicroShift configuration file by adding the following YAML snippet to /etc/microshift/config.yaml:

   sudo tee /etc/microshift/config.yaml > /dev/null <<EOF
   node:
     hostnameOverride: hostnameOverride: $(echo $NAME)
     nodeIP: $(echo $IP)
   EOF

6. MicroShift is now ready to use the loopback device for cluster communications. Finish preparing the device for offline use.

   1. If the device currently has a NIC attached, disconnect the device from the network.
   2. Shut down the device and disconnect the NIC.
   3. Restart the device for the offline configuration to take effect.

7. Restart the MicroShift host to apply the configuration changes by running the following command:

   $ sudo systemctl reboot 1

   1

   This step restarts the cluster. Wait for the greenboot health check to report the system healthy before implementing verification.

1. Verify that the MicroShift cluster is running by entering the following command:

   $ export KUBECONFIG=/var/lib/microshift/resources/kubeadmin/kubeconfig
   $ sudo -E oc get pods -A

   Example output

   NAMESPACE                  NAME                                       READY   STATUS    RESTARTS      AGE
   kube-system                csi-snapshot-controller-74d566564f-66n2f   1/1     Running   0             1m
   kube-system                csi-snapshot-webhook-69bdff8879-xs6mb      1/1     Running   0             1m
   openshift-dns              dns-default-dxglm                          2/2     Running   0             1m
   openshift-dns              node-resolver-dbf5v                        1/1     Running   0             1m
   openshift-ingress          router-default-8575d888d8-xmq9p            1/1     Running   0             1m
   openshift-ovn-kubernetes   ovnkube-master-gcsx8                       4/4     Running   1             1m
   openshift-ovn-kubernetes   ovnkube-node-757mf                         1/1     Running   1             1m
   openshift-service-ca       service-ca-7d7c579f54-68jt4                1/1     Running   0             1m
   openshift-storage          topolvm-controller-6d777f795b-bx22r        5/5     Running   0             1m
   openshift-storage          topolvm-node-fcf8l                         4/4     Running   0             1m