[root@k8s yaml-demo]# kubectl apply -f mysql-pod-ConfigMap.yaml 
configmap/mysql-config unchanged
The Pod "mysql-pod-ConfigMap" is invalid: metadata.name: Invalid value: "mysql-pod-ConfigMap": a lowercase RFC 1123 subdomain must consist of lower case alphanumeric characters, '-' or '.', and must start and end with an alphanumeric character (e.g. 'example.com', regex used for validation is '[a-z0-9]([-a-z0-9]*[a-z0-9])?(\.[a-z0-9]([-a-z0-9]*[a-z0-9])?)*')