Mike Lutaaya: You need to create a non-root user on your VM to run devstack. You could use this few commands;

2. Set up a Stack user with superuser permissions

Devstack should be run as a non-root user with sudo enabled (standard logins to cloud images such as “ubuntu” or “cloud-user” are usually fine). Since this user will be making many changes to your system, it will need to have sudo privileges.

a) Create the group stack and add the user stack in it:

$sudo groupadd stack

$sudo useradd -g stack -s /bin/bash -d /opt/stack -m stack

b) Grant superuser permissions to the stack user:

$sudo su

$echo "stack ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers

c) Logout as your default user:
Ctrl+d

d) Create a password for the stack user:

$sudo passwd stack

e) Now to login as the stack user:

$su stack

f) Go to the home directory of the stack user:

$cd ~