Provisioning Fedora CoreOS on Hetzner

This guide shows how to provision new Fedora CoreOS (FCOS) nodes on Hetzner. Fedora CoreOS is currently not available as an option in the operating system selection on Hetzner. Thus you must first download the Fedora CoreOS disk image for Hetzner, then create a snapshot from it in your Hetzner account using the hcloud-upload-image tool, and finally create your servers from this snapshot.

Support for Fedora CoreOS on Hetzner is considered emerging, in that it does not yet offer an optimized user experience and relies on tools not officially supported by Hetzner. See issue #1324 for more details.

The hcloud-upload-image tool is not an official Hetzner Cloud product and Hetzner Cloud does not provide support for it. Alternatively, you can also use the official packer-plugin-hcloud to install the image via coreos-installer.

In order to create a snapshot, the hcloud-upload-image tool will provision a small server and boot it in rescue mode. As this server is short lived, the cost should be very limited. The resulting snapshots are charged per GB per month. See Backups/Snapshots in the Hetzner Cloud documentation. You may delete this snapshot once the server has been provisioned.

Prerequisites

Before provisioning an FCOS machine, you must have an Ignition configuration file containing your customizations. If you do not have one, see Producing an Ignition File.

Fedora CoreOS has a default core user that can be used to explore the OS. If you want to use it, finalize its configuration by providing e.g. an SSH key.

If you do not want to use Ignition to get started, you can make use of the Afterburn support and only configure SSH keys.

You also need to have access to a Hetzner account. The examples below use the hcloud command-line tool, the hcloud-upload-image tool and jq as a command-line JSON processor.

Downloading an Hetzner image

Fedora CoreOS is designed to be updated automatically, with different schedules per stream. Once you have picked the relevant stream, download and verify the latest Hetzner image:

ARCH="x86_64"    # or "aarch64"
STREAM="stable"  # or "testing", "next"
coreos-installer download -s "$STREAM" -p hetzner -a "$ARCH" -f raw.xz

Both x86_64 and aarch64 architectures are supported on Hetzner.

Alternatively, you can manually download an Hetzner image from the download page. Verify the download, following the instructions on that page.

Creating a snapshot

Use the hcloud-upload-image to create a snapshot from this image:

IMAGE_NAME="fedora-coreos-41.20250213.0-hetzner.x86_64.raw.xz"
export HCLOUD_TOKEN="<your token>"
STREAM="stable"     # or "testing", "next"
HETZNER_ARCH="x86"  # or "arm"

hcloud-upload-image upload \
    --architecture "$HETZNER_ARCH" \
    --compression xz \
    --image-path "$IMAGE_NAME" \
    --labels os=fedora-coreos,channel="$STREAM" \
    --description "Fedora CoreOS ($STREAM, $ARCH)"

The hcloud-upload-image tool uses different names for architectures (x86_64 → x86, aarch64 → arm).

Wait for the process to complete and validate that you have a snapshot:
```
hcloud image list --type=snapshot --selector=os=fedora-coreos
```

Launching a server

If you don’t already have an SSH key uploaded to Hetzner, you may upload one:

Example uploading an SSH key to Hetzner

SSH_PUBKEY="ssh-ed25519 ..."
SSH_KEY_NAME="fedora-coreos-hetzner"
hcloud ssh-key create --name "$SSH_KEY_NAME" --public-key "$SSH_PUBKEY"

Launch a server. Your Ignition configuration can be passed to the VM as its user data, or you can skip passing user data if you just want SSH access. This provides an easy way to test out FCOS without first creating an Ignition config.

Example launching FCOS on Hetzner using an Ignition configuration file and SSH key

IMAGE_ID="$(hcloud image list \
    --type=snapshot \
    --selector=os=fedora-coreos \
    --output json \
    | jq -r '.[0].id')"
SSH_KEY_NAME="fedora-coreos-hetzner"  # See: hcloud ssh-key list
DATACENTER="fsn1-dc14"                # See: hcloud datacenter list
TYPE="cx22"                           # See: hcloud server-type list
NAME="fedora-coreos-test"
IGNITION_CONFIG="./config.ign"
hcloud server create \
    --name "$NAME" \
    --type "$TYPE" \
    --datacenter "$DATACENTER" \
    --image "$IMAGE_ID" \
    --ssh-key "$SSH_KEY_NAME" \
    --user-data-from-file "$IGNITION_CONFIG"

While the Hetzner documentation and website mentions cloud-init and "cloud config", FCOS does not support cloud-init. It accepts only Ignition configuration files.

You now should be able to SSH into the instance using the associated IP address.
Example connecting
```
ssh core@"$(hcloud server ip "$NAME")"
```

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