***create_key**: If defined to True then ssh-keygen is called on local machine and then:
private key copied to ~/.ssh on management node
public key inserted into authroized_keys on SQL_BK_DEST_HOST
*private key copied to ~/.ssh on management node
*public key inserted into authroized_keys on SQL_BK_DEST_HOST
***SQL_BK_DEST_HOST:** IP number of Machine where we store mysql dumps
***SQL_BK_DEST_DIR:** Directory on backup machine for mysql dumps. Note this is owned by ec2-user and is manually created. It should be cluster-specific, i.e. different for each cluster