Description:
This is feature request.

Server variables "default_password_lifetime" is introduced from 5.7.4.

http://dev.mysql.com/doc/refman/5.7/en/server-system-variables.html#sysvar_default_passwor...

Its implicit default value is "360", but, that's too danger value for users who is not expert to MySQL.
Because 5.6 and earlier releases don't have such password-lifetime implementation, thus there is few information about this new implementation.

Password-expiration will make to stop applications.

How to repeat:
1. Newbie and/or lightweight users install 5.7.
2. They sets up account without knowing default_password_lifetime.
3. After 360 days, their application will be stopped.

Suggested fix:
1. Default value of default_password_lifetime set "0"

And/or

2. Inform by error-log and/or returning warning, "this account's password will be expired", when the time is near to its lifetime.