Download and install VirtualBox.

Download the CoreOS ISO

Create a new VM in VirtualBox

  • For the OS, Other Linux, 64-bit should be fine
  • Give the VM 1gb of memory, like your physical hardware has.
  • Create a disk of whatever size you want. I made a VMDK file that could expand dynamically up to 8gb.

Mount the ISO in the VM

  • Right click on the VM and click settings
  • Go to the storage tab
  • Click on the empty disk on the left
  • Click the disk icon next to IDE Secondary on the right
  • Choose the ISO
  • Check the Live CD/DVD box
  • Go to the network tab
  • Make sure NAT is selected
  • Edit the port forwarding settings and add a rule for:
Host IP: 127.0.0.1
Host Port: 22022
Guest IP: 10.0.2.15
Guest Port: 22

Start the VM. It should boot into CoreOS to a core@localhost prompt.

Run sudo fdisk -l. You should have a /dev/sda device. That's the VM's disk.

Upload your SSH public key to an HTTP server somewhere that the VM can access. Suggestion:

cd ~/.ssh
python -m SimpleHTTPServer

Use curl to download your SSH public key to the box.

curl http://10.0.2.2:8000/id_rsa.pub -O

Rename the file to cloud-config.yaml.

Edit the file with vim and make it look something like:

#cloud-config
ssh_authorized_keys:
  - ssh_rsa AAAAB3NzaC1...snip

Use coreos-install to install to the VM's disk with your keys:

sudo coreos-install -d /dev/sda -C stable -c ~/cloud-config.yaml
sudo poweroff

Edit the VM settings again and remove the ISO from the machine.

Power it up again. You should end up at a login prompt.

SSH into the VM:

$ ssh -p 22022 core@127.0.0.1
Last login: Thu Apr 23 15:50:31 2015 from 192.168.59.3
CoreOS stable (633.1.0)
core@localhost ~ $