http://kubernetes.io/docs/user-guide/labels
kubernetes-docs-labels#maps "Labels selectors for both objects are defined in json or yaml files using maps, and only equality-based requirement selectors are supported:" kubernetes-docs-labels#maps
kubernetes-docs-labels#add-label-using-kubectlkubectl label nodes <node-name> <label-key>=<label-value> kubernetes-docs-labels#add-label-using-kubectl
The issue in the doc is:
"or restricting negative matching via exists operator: $ kubectl get pods -l 'environment,environment notin (frontend)'"