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Booting Fedora CoreOS
Now that we have an Ignition config, we can boot a virtual machine with it. This tutorial uses the QEMU image with `libvirt`, but you should be able to use the same Ignition config on all the platforms supported by Fedora CoreOS.
We use `virt-install` to create a new Fedora CoreOS virtual machine with a specific config:
# Setup the correct SELinux label to allow access to the config
chcon --verbose --type svirt_home_t autologin.ign
# Start a Fedora CoreOS virtual machine
virt-install --name=fcos --vcpus=2 --ram=2048 --os-variant=fedora-coreos-stable \
--import --network=bridge=virbr0 --graphics=none \
--qemu-commandline="-fw_cfg name=opt/com.coreos/config,file=${PWD}/autologin.ign" \
The `virt-install` command will start an instance named `fcos` from the `fedora-coreos.qcow2` image using the `autologin.ign` Ignition config. It will auto-attach the serial console of the machine so you will be able to see the image bootup messages.
We use the `backing_store` option to `virt-install --disk` to quickly create a new disk image and avoid writing to the original image we have downloaded. This new disk image can be easily thrown away.
Depending on your version of `virt-install`, you may not be able to use `--os-variant=fedora-coreos-stable` and will get an error. In this case, you should pick an older Fedora variant (`--os-variant=fedora31` for example). You can find the variants that are supported by you current version of `virt-install` with `osinfo-query os | grep '^\s*fedora'`.
Once the machine is booted up you should see a few prompts and then you should be automatically logged in and presented with a bash shell:
[ OK ] Started rpm-ostree System Management Daemon.
Fedora CoreOS 32.20200715.3.0
Kernel 5.7.8-200.fc32.x86_64 on an x86_64 (ttyS0)
SSH host key: SHA256:XlbayjbgDKNoAAHQxsEL5Q7BdwLxxWSw4NXN9SALLmo (ED25519)
SSH host key: SHA256:3sx5jseteO4BvdOMWIi0J4koQL015mLonnD0UPTtnZk (ECDSA)
SSH host key: SHA256:K0fn5/TMJOoMs7Fu7RRkE7IBEf2t8OYCfVaVc+GJWGs (RSA)
ens2: fe80::5054:ff:feb9:3d97
Ignition: user provided config was applied
No ssh authorized keys provided by Ignition or Afterburn
tutorial login: core (automatic login)
[core@tutorial ~]$
Let's verify that our configuration has been correctly applied. As we were automatically logged in to the terminal, we can safely assume that the systemd dropin has been created:
[core@tutorial ~]$ systemctl cat serial-getty@ttyS0.service
# /usr/lib/systemd/system/serial-getty@.service
# /etc/systemd/system/serial-getty@ttyS0.service.d/autologin-core.conf
# Override Execstart in main unit
# Add new Execstart with `-` prefix to ignore failure`
ExecStart=-/usr/sbin/agetty --autologin core --noclear %I $TERM
We can also check that the hostname has correctly been set:
[core@tutorial ~]$ cat /etc/hostname
[core@tutorial ~]$ hostnamectl
Static hostname: tutorial
Icon name: computer-vm
Chassis: vm
Machine ID: d06466128a1c4a6ab255d9581748755c
Boot ID: 2a19abb9681e442cb1e10271350bfff3
Virtualization: kvm
Operating System: Fedora CoreOS 32.20200715.3.0
CPE OS Name: cpe:/o:fedoraproject:fedora:32
Kernel: Linux 5.7.8-200.fc32.x86_64
Architecture: x86-64
Exploring Fedora CoreOS internals
Once we have access to the console of the machine we can browse around a bit to see some of the different pieces of the operating system. For example, even though this is an OSTree based system it was still composed via RPMs and we can inspect the system to see what it was composed of: