We will use SSH to run commands on a worker node.
In order to SSH into a worker node, you first have to find the external IP address of the node:
$ kubectl get nodes -o wide
NAME STATUS ROLES AGE VERSION EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
metakube-fhgbvx12xg-4kmht Ready <none> 1d v1.10.3 123.123.123.1 Ubuntu 16.04.4 LTS 4.4.0-116-generic docker://17.3.2
metakube-fhgbvx12xg-jzspq Ready <none> 1d v1.10.3 123.123.123.2 Ubuntu 16.04.4 LTS 4.4.0-116-generic docker://17.3.2
metakube-fhgbvx12xg-t8nwc Ready <none> 1d v1.10.3 123.123.123.3 Ubuntu 16.04.4 LTS 4.4.0-116-generic docker://17.3.2
You can now use ssh to get access to the worker node:
ssh ubuntu@123.123.123.1
The default username depends on the used operating system, for a complete list see Supported Operating Systems.