Does ambari agent renew kerberos ticket automaticly?

[Zhang Ruiqiang]

Hi all:
    When kerberos is enabled, the authed user and service get the ticket use a 
"kinit" command, the ticket will expired after about 6 days.
    So, my question is: does ambari agent will renew the ticket automaticly, if 
so, where is the source code to implement this.

Thanks.