Yaml definition of the Kubernetes Pod to be used as slave. For example (JENKINS_URL should be substituted):

apiVersion: "v1"
kind: "Pod"
metadata:
  name: "jenkins-slave"
  labels:
    name: "jenkins-slave"
spec:
  containers:
    - name: "jenkins-slave"
      image: "jenkinsci/jnlp-slave"
  env:
    - name: "JENKINS_URL"
      value: "${JENKINS_URL}"