configmap yaml 文件：

[root@master ~]# kubectl apply -f configmap.yaml
configmap/my-db-config unchanged
pod/busybox created
[root@master ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
busybox 0/1 Completed 1 3s

[root@master ~]# kubectl logs busybox
KUBERNETES_PORT=tcp://10.96.0.1:443
KUBERNETES_SERVICE_PORT=443
HOSTNAME=busybox
SHLVL=1
HOME=/root
KUBERNETES_PORT_443_TCP_ADDR=10.96.0.1
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
KUBERNETES_PORT_443_TCP_PORT=443
KUBERNETES_PORT_443_TCP_PROTO=tcp
KUBERNETES_PORT_443_TCP=tcp://10.96.0.1:443
KUBERNETES_SERVICE_PORT_HTTPS=443
PWD=/
KUBERNETES_SERVICE_HOST=10.96.0.1

没有显示db-url=localhost ，执行命令没有报错。