Receive "ssh action: AUTH_FAILED: Not able to perform operation" when using ssh function in Oozie

[#1]

SYMPTOM: When you create an Oozie workflow which contains a SSH function, it can fail with an error of "Not able to perform operation [ssh -o PasswordAuthentication=no -o KbdInteractiveDevices=no -o StrictHostKeyChecking=no -o ConnectTimeout=20 root@localhost mkdir -p oozie-oozi/0000009-131023115150605-oozie-oozi-W/Ssh--ssh/ ] | ErrorStream: Permission denied (publickey,gssapi-keyex,gssapi-with-mic,password)."

ROOT CAUSE: Passwordless SSH must be setup correctly from oozie@server1 to $user@server2
For example: 

RESOLUTION: 
If an Oozie workflow contains an ssh command from server 1 to server 2 as root, then the passwordless SSH must be setup as the following:

oozie@server1 > root@server2

This article created by Hortonworks Support (Article: 000001722) on 2015-04-01 11:05
OS: Linux
Type: Configuration,Executing_Jobs

[#2]

Do you enter that line in the workflow itself to set up passwordless SSH?

[#3]

Can someone please elaborate more on how to set up passwordless SSH or embed into workflow? Thank you.