Provisioning Fedora CoreOS on Amazon Web Services

This guide shows how to provision new Fedora CoreOS (FCOS) instances on the Amazon Web Services (AWS) cloud platform.

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.

You also need to have access to an AWS account. The examples below use the aws command-line tool, which must be separately installed and configured beforehand.

Launching a VM instance

Minimal Example

New AWS instances can be directly created from the public FCOS images. You can find the latest AMI for each region from the download page.

If you are only interested in exploring FCOS without further customization, you can use a registered SSH key-pair for the default core user.

To test out FCOS this way you’ll need to run the aws ec2 run-instances command and provide some information to get the instance up and running. The following is an example command you can use:

Launching a new instance

NAME='instance1'
SSHKEY='my-key'     # the name of your SSH key: `aws ec2 describe-key-pairs`
IMAGE='ami-xxx'     # the AMI ID found on the download page
DISK='20'           # the size of the hard disk
REGION='us-east-1'  # the target region
TYPE='m5.large'     # the instance type
SUBNET='subnet-xxx' # the subnet: `aws ec2 describe-subnets`
SECURITY_GROUPS='sg-xx' # the security group `aws ec2 describe-security-groups`
aws ec2 run-instances                     \
    --region $REGION                      \
    --image-id $IMAGE                     \
    --instance-type $TYPE                 \
    --key-name $SSHKEY                    \
    --subnet-id $SUBNET                   \
    --security-group-ids $SECURITY_GROUPS \
    --tag-specifications "ResourceType=instance,Tags=[{Key=Name,Value=${NAME}}]" \
    --block-device-mappings "VirtualName=/dev/xvda,DeviceName=/dev/xvda,Ebs={VolumeSize=${DISK}}"

You can find out the instance’s assigned IP by running aws ec2 describe-instances

You now should be able to SSH into the instance using the associated IP address.

Example connecting

ssh core@<ip address>

Customized Example

In order to launch a customized FCOS instance, a valid Ignition configuration must be passed as its user data at creation time. You can use the same command from the Minimal Example but add --user-data file://path/to/config.ign argument:

The SSH key for the core user is supplied via Afterburn in this example as well.

Launching and customizing a new instance

NAME='instance1'
SSHKEY='my-key'     # the name of your SSH key: `aws ec2 describe-key-pairs`
IMAGE='ami-xxx'     # the AMI ID found on the download page
DISK='20'           # the size of the hard disk
REGION='us-east-1'  # the target region
TYPE='m5.large'     # the instance type
SUBNET='subnet-xxx' # the subnet: `aws ec2 describe-subnets`
SECURITY_GROUPS='sg-xx' # the security group `aws ec2 describe-security-groups`
USERDATA='/path/to/config.ign' # path to your Ignition config
aws ec2 run-instances                     \
    --region $REGION                      \
    --image-id $IMAGE                     \
    --instance-type $TYPE                 \
    --key-name $SSHKEY                    \
    --subnet-id $SUBNET                   \
    --security-group-ids $SECURITY_GROUPS \
    --user-data "file://${USERDATA}"      \
    --tag-specifications "ResourceType=instance,Tags=[{Key=Name,Value=${NAME}}]" \
    --block-device-mappings "VirtualName=/dev/xvda,DeviceName=/dev/xvda,Ebs={VolumeSize=${DISK}}"

By design, cloud-init configuration and startup scripts are not supported on FCOS. Instead, it is recommended to encode any startup logic as systemd service units in the Ignition configuration.

You can find out the instance’s assigned IP by running aws ec2 describe-instances

You now should be able to SSH into the instance using the associated IP address.

Example connecting

ssh core@<ip address>

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