Install sftp on centos docker container

Tried installing sftp on centos 7.0 docker image using below but once inside the docker I dont see sftp utility.

from Docker - SFTP installation

RUN yum install -y ntp \
    && yum install -y vsftpd

Also tried by installing openssh-server

RUN yum install -y openssh-server passwd

If these installs are not correct, what should I be installing to get sftp? Do I need to start any service to enable sftp? Please help.