This small setup can be used to provision Flatcar nodes on Equinix Metal with the instance user data (Ignition config) used for reconfiguration. The advantage is to be able to keep persistent data, keep the same IP address, and to reduce the time of re-applying a configuration change.
This setup uses flatcar-reset to clean the rootfs while preserving allowed paths, but you can also use the reinstall option and drop reprovision-helper at the expense of losing all rootfs data.
Edit the Container Linux Config cl/machine-mynode.yaml.tmpl file if you like, then create the following terraform.tfvars with a machine mynode, corresponding to the Container Linux Config file name. If you add more machines, create new files for them under cl/.
cluster_name = "mycluster"
machines = ["mynode"]
plan = "t1.small.x86"
facilities = ["sjc1"]
project_id = "1...-2...-3...-4...-5..."
ssh_keys = ["ssh-rsa AA... me@mail.net"]
It is recommended to register your SSH key in the Equinix Metal Project to use the out-of-band console. Since Flatcar will fetch this key, too, you can remove it from the YAML config.
Now run Terraform (version 13) as follows:
export METAL_AUTH_TOKEN=...
terraform init
terraform apply
Log in via ssh core@IPADDRESS (maybe add -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -o NumberOfPasswordPrompts=0).
When you make a change to machine-mynode.yaml.tmpl (e.g., my-setting v1 to my-setting v2 and run terraform apply again, the instance is just rebooted instead of recreated and the new Ignition config applied while keeping wanted data (see KEEPPATHS setting) and discarding the rest.
We can run this command to compare the values of /etc/config-side-effect and /mydata/data before and after the run. We should see that /etc/config-side-effect changes while /mydata/data stays the same.
ssh core@IPADDRESS "head /etc/config-side-effect /mydata/data"