Some versions of sudo have a default configuration that prevents sudo from being invoked from a non-interactive shell. In order for the agent to run it's commands non-interactively, some defaults need to be overridden.

Defaults exempt_group = ambari
Defaults !env_reset,env_delete-=PATH
Defaults: ambari !requiretty 

To re-iterate, this sudo configuration must be done on every node in the cluster. To ensure that the configuration has been done properly, you can su to the ambari user and run sudo -l. There, you can double-check that there are no warnings, and that the configuration output matches what was just applied.