Fedora CoreOS working on VirtualBox

Note, a lot of this was inspired from this GitHub gist.

Hi! I wanted to build up a VM for Fedora CoreOS, and these were my steps to get it to work. It’s just a basic installation, and enough to play with it. I have a romatic goal of moving all my servers and applications to an immutable OSs, and getting my hands on a disposable Fedora CoreOS is the first learning step.

Prereqs

• Download and install VirtualBox.
• Download the CoreOS ISO from here

Create a new VM in VirtualBox

• Select Fedora 64-bit
• Give the VM at least 4 Gigs, I gave mine 8 Gigs
• 16 Gigs for the hard drive to test
• Set the network to “NAT” and add the following to the port forwarding:
  • Host IP: 127.0.0.1
  • Host Port: 2222
  • Guest IP: 10.0.2.15
  • Guest Port: 22
• Mount the LiveCD as an Optical Device
• Confirm that you’ll boot off it as your first device

Boot the machine

• Go ahead and boot the machine, and you should boot into something like:

[core@localhost ~]$

Configure your ignition file

There are a ton of options for your file, see here but for this basic installation take the following yaml file.

variant: fcos
version: 1.0.0
passwd:
  users:
    - name: core
      ssh_authorized_keys:
        - ssh-rsa AAAA...

Put it on your local file system, and add your id_rsa.pub as the - ssh-rsa AAA line. Save the file as something like example.yaml. Next, you want to convert it to the json for the .ignfile. Run the following on your local machine, (this is assuming you have Docker installed):

docker run -i --rm quay.io/coreos/fcct:release --pretty \
   --strict < example.yaml > example.ign

This will create the json friendly version from your yaml.

Get the ign file onto your VM

Next you need to get your file onto your VM. The easiest way to do this is in your directory with the example.ign run the following to start a simple python3 webserver.:

python3 -m http.server

Now you can go to your booted Fedora CoreOS machine and run a curl to bring it to the box: (10.0.2.2 is the default host machine, check yours by route -n whatever the Gateway is)

curl -LO 10.0.2.2:8000/example.ign

Note: by default the python server runs on port 8000.You should now have your example.ign on your Fedora CoreOS machine.

Install the base image

Now that you have your example.ign on the machine you can run the installer, there are multiple options but the basic command is the following:

sudo coreos-installer install /dev/sda --ignition-file example.ign

You should see a default image being pulled down, and it should inject yourexample.ign file. It will be done when you see:

Install complete.

Now that it’s done, you need to sudo shutdown -h now and pull the ISOfrom the Virtual Drive. Power up the machine again.

This will start going through the first boot, and then you should see:

localhost login:

Now go to another terminal on your local machine and SSH in:

ssh 127.0.0.1 -p 2222 -l core
Fedora CoreOS 31.20200505.3.0
Tracker: https://github.com/coreos/fedora-coreos-tracker
Discuss: https://discussion.fedoraproject.org/c/server/coreos/

[core@localhost ~]$

Congratulations! You now have a Fedora CoreOS machine ready to play with.

Verifying your docker installation

Just as a quick sanity check, you can run the following to make sure you’re machinecan pull from the docker registry and also run the containers:

[core@localhost ~]$ sudo docker run hello-world
Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
0e03bdcc26d7: Pull complete
Digest: sha256:6a65f928fb91fcfbc963f7aa6d57c8eeb426ad9a20c7ee045538ef34847f44f1
Status: Downloaded newer image for hello-world:latest

Hello from Docker!
This message shows that your installation appears to be working correctly.

Hopefully this’ll help you get your hands on Fedora CoreOS to play around with.