Install DevStack on CentOS 7, without dependency errors

DevStack is a single machine based OpenStack version which can be simply used for any development on OpenStack. However, installing DevStack is not an easy process especially when you face a dependency error (as like any other dependency problem...). In this article, I will describe how to install DevStack on CentOS 7 without any dependency error.

1. Install CentOS 7.
Download the Minimal ISO version of CentOS 7 and install. If you install CentOS/DevStack on a virtual machine, my personal recommended settings are:
- CPU: 2 cores
- RAM: 4GB
- HDD: 10GB

2. Set up network
CentOS 7 uses NetworkManager by default, which means network can be set up by running 'nmtui' tool. If you don't want to use NetworkManager, disable it and use the traditional way by editing /etc/sysconfig/network-scripts/ifcfg-* files.

3. Install git and add user 'stack'.
First, install git software using yum:

# sudo yum install -y git

Then, add a non-root user 'stack' to run devstack. Details can be found on the official document:
https://docs.openstack.org/devstack/latest/#add-stack-user

Switch to the user 'stack' using su command:

# sudo su - stack

4. Clone DevStack git repository
Clone DevStack git repository using the following command:

# git clone https://git.openstack.org/openstack-dev/devstack
# cd devstack

5. Change to the recent stable branch *IMPORTANT*

Use the following command to change to the 'most recent' stable branch.

# git checkout stable/pike

Find the latest branch here:

https://github.com/openstack-dev/devstack/branches

When git repository is cloned, it syncs to the latest master branch of DevStack which might include some bugs resulting in installation error. I strongly suggest to use the latest 'stable' branch instead of master branch. Master branch includes all new features and functions which might cause a problem.

Also, do NOT use any OLD stable branches. Use only the most recent stable branch (stable/pike as of October 2017), because DevStack always selects the most recent yum package repository on their process regardless of the selected git branch.

6. Create local.conf

Create a local.conf file in devstack directory. The contents should be:

[[local|localrc]]

ADMIN_PASSWORD=secret

DATABASE_PASSWORD=$ADMIN_PASSWORD

RABBIT_PASSWORD=$ADMIN_PASSWORD

SERVICE_PASSWORD=$ADMIN_PASSWORD

HOST_IP=127.0.0.1

"secret" and the local ip address should be changed. Also, add extra features if needed. For example, if ceilometer is necessary, add the following line in the local.conf file.

enable_plugin ceilometer https://git.openstack.org/openstack/ceilometer stable/pike

7. Snapshot the virtual machine (Optional)

If you're installing DevStack on a VM, this is the best time to snapshot the VM because './stack.sh' script messes up all the configuration and package installation of our clean-installed CentOS 7.

8. Start the installation script

# ./stack

This command will start the installation of DevStack. The script uses python, pip, git, yum, and other tools to install DevStack, which means it simply changes all the package installation and dependencies based on DevStack git repository and the recent OpenStack release.

If this script ended up with any error, e.g. dependency error, version error, or failure of any module installation, then restore using the snapshot of Step 7, and then go back to Step 5 to check what branch is used for git repository. Make sure the git branch is changed to the MOST RECENT OpenStack release.