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Updated details on VM builds

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David Young
2017-07-16 22:59:04 +12:00
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# Introduction
We start building our cloud with virtual machines. You could use bare-metal machines as well, the configuration would be the same. Given that most readers (myself included) will be using virtual infrastructure, from now on I'll be referring strictly to VMs.
Let's start building our cloud with virtual machines. You could use bare-metal machines as well, the configuration would be the same. Given that most readers (myself included) will be using virtual infrastructure, from now on I'll be referring strictly to VMs.
I chose the "[Atomic](https://www.projectatomic.io/)" CentOS/Fedora image for the VM layer because:
1. I want less responsibility for maintaining the system, including ensuring regular software updates and reboots. Atomic's idempotent nature means the OS is largely real-only, and updates/rollbacks are "atomic" (haha) procedures, which can be easily rolled back if required.
2. For someone used to administrating servers individually, Atomic is a PITA. You have to employ [tricky](atomic-trick2) [tricks](atomic-trick1) to get it to install in a non-cloud environment. It's not designed for tweaking or customizing beyond what cloud-config is capable of. For my purposes, this is good, because it forces me to change my thinking - to consider every daemon as a container, and every config as code, to be checked in and version-controlled. Atomic forces this thinking on you.
3. I want the design to be as "portable" as possible. While I run it on VPSs now, I may want to migrate it to a "cloud" provider in the future, and I'll want the most portable, reproducible design.
[atomic-trick1]:https://spinningmatt.wordpress.com/2014/01/08/a-recipe-for-starting-cloud-images-with-virt-install/
[atomic-trick2]:http://blog.oddbit.com/2015/03/10/booting-cloud-images-with-libvirt/
## Ingredients
3 x Virtual Machines, each with:
* CentOS/Fedora Atomic
* At least 1GB RAM
* At least 20GB disk space (but it'll be tight)
* Connectivity to each other within the same subnet, and on a low-latency link (i.e., no WAN links)
* At least 20GB disk space (_but it'll be tight_)
* Connectivity to each other within the same subnet, and on a low-latency link (_i.e., no WAN links_)
## Preparation
### Install Virtual machines
1. Install Virtual machines
2. Setup super-user access for your admin user, as a member of the "docker" group
1. Install / launch virtual machines.
2. The default username on CentOS atomic is "centos", and you'll have needed to supply your SSH key during the build process. If you're not using a platform with cloud-init support (i.e., you're building a VM manually, not provisioning it through a cloud provider), you'll need to refer to [trick #1][atomic-trick1] and [#2][atomic-trick2] for a means to override the automated setup, apply a manual password to the CentOS account, and enable SSH password logins.
I chose the "Atomic" CentOS/Fedora image because:
### Upgrade Atomic
1. I want less responsibility for maintaining the system, including ensuring regular software updates and reboots. Atomic's idempotent nature means the OS is largely real-only, and updates/rollbacks are "atomic" (haha) procedures, which can be easily rolled back if required.
2. For someone used to administrating servers individually, Atomic is a PITA. You have to employ [tricky](http://blog.oddbit.com/2015/03/10/booting-cloud-images-with-libvirt/) [tricks](https://spinningmatt.wordpress.com/2014/01/08/a-recipe-for-starting-cloud-images-with-virt-install/) to get it to install in a non-cloud environment. It's not designed for tweaking or customizing beyond what cloud-config is capable of. For my purposes, this is good, because it forces me to change my thinking - to consider every daemon as a container, and every config as code, to be checked in and version-controlled. Atomic forces this thinking on you.
3. I want the design to be as "portable" as possible. While I run it on VPSs now, I may want to migrate it to a "cloud" provider in the future, and I'll want the most portable, reproducible design.
Run ```atomic host upgrade```, and reboot if necessary.
atomic host upgrade
## Serving
After completing the above, you should have:
* [X] 3 fresh atomic instances, at the latest releases
* [X] A user belonging to the docker group for administration