This was useful, as I couldn't figure out how to add the cloud-config files I use for my Vagrant-base CoreOS cluster.
Here's another question:
If I have a droplet up and running already, anyone know how I might change it from Ubuntu to the new CoreOS image? I'd rather change it than create a new one to maintain the same public IP, or else I have to have my DNS records updated, which takes time, and is outside my direct control.
CoreOS is not a drop-in replacement for Ubuntu; migrating to it requires re-deploying your services inside Docker containers. I would think you might want to run your service implementations in parallel and then cut over later.
Can you not move IP's between Digitalocean droplets?
Similarly, I created a new coreos droplet just to play around, neglected to add the cloud_config yaml configuration. I couldn't find a setting to add it to the droplet afterwards.
Semantically, cloud-config is really not something you can add after. cloud-config comes from Ubuntu, but the semantics are a virtual clone of the ones of AWS's cfn-init; the point of both is to inject your config during initial instance bring-up, when system config files are first being generated by the instance provisioner. You can't really run them again once you've already brought up the instance, since they'd just messily trample over their previously spewed configs without removing the previous ones first.
With cloud-config, you're basically expected to be using ephemeral (or nearly-so) instances, particularly within the context of an autoscaling group or equivalent. The lifecycle is supposed to go "[scale up], provision, configure, start services; [crash or scale down], terminate, repeat." CoreOS adds to this soft reboots for upgrades, but definitely still assumes cattle, not snowflake, instances.
Here's another question: If I have a droplet up and running already, anyone know how I might change it from Ubuntu to the new CoreOS image? I'd rather change it than create a new one to maintain the same public IP, or else I have to have my DNS records updated, which takes time, and is outside my direct control.