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.
Prérequis
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.
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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:
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
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You now should be able to SSH into the instance using the associated IP address.
ssh core@<adresse ip>
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.
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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
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You now should be able to SSH into the instance using the associated IP address.
ssh core@<adresse ip>
Remote Ignition configuration
As user-data is limited to 16 KB, you may need to use an external source for your Ignition configuration. A common solution is to upload the config to a S3 bucket, as the following steps show:
NAME='instance1'
aws s3 mb s3://$NAME-infra
NAME='instance1'
CONFIG='/path/to/config.ign' # path to your Ignition config
aws s3 cp CONFIG s3://$NAME-infra/bootstrap.ign
You can verify the file have been correctly uploaded:
NAME='instance1'
aws s3 ls s3://$NAME-infra/
Then create a minimal Ignition config as follows:
variant: fcos
version: 1.5.0
ignition:
config:
replace:
source: s3://instance1-infra/bootstrap.ign
Then you can launch the instance using the same command as Customized Example, passing the minimal configuration you just created.
Once the first boot is completed, make sure to delete the configuration as it may contain sensitive data. See Configuration cleanup.
Configuration cleanup
If you need to have secrets in your Ignition configuration you should store it into a S3 bucket and have a minimal configuration in user-data. Once the instance has completed the first boot, clear the S3 bucket as any process or container running on the instance could access it. See the Ignition documentation for more advice on secret management.
NAME='instance1'
aws s3 rm CONFIG s3://$NAME-infra/bootstrap.ign
Optionnally, you can delete the whole bucket:
NAME='instance1'
aws s3 rb s3://$NAME-infra
The instance’s user data cannot be modified without stopping the instance. |
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