agent uniqueness change

[anda-ren]

Is your feature request related to a problem? Please describe.
Now we give an unique constrain on anget through ip address. But the ip address of an agent is constantly changing in K8S context. A new uniqueness field of agent is required

Describe the solution you'd like

• add an unique field of agent called serial_number
• agents report the serial_number to controller and make sure these numbers are universal unique