How to pass password automatically for rsync SSH command?

Use "sshpass" non-interactive ssh password provider utility

On Ubuntu

 sudo apt-get install sshpass

Command to rsync

 /usr/bin/rsync -ratlz --rsh="/usr/bin/sshpass -p password ssh -o StrictHostKeyChecking=no -l username" src_path  dest_path

You should use a keyfile without passphrase for scripted ssh logins. This is obviously a security risk, take care that the keyfile itself is adequately secured.

Instructions for setting up passwordless ssh access