I’ve been experimenting a lot with CoreOS Container Linux (formerly simply CoreOS). One of the issues I’ve had regularly was getting my cloud-config to the server after an initial install. There’s no meta data drive or something similar on bare metal servers or normal VPS.
Easy solution: Bypass the authentication. If you have access to a VNC or something similar, you can add coreos.autologin=tty0 (or just omit the =tty0) kernel option to get to a login shell directly.
If you don’t know where to put that, it needs to be put in the Grub command line. Here’s an image of it.
So you need to press e in the Grub menu, enter the option behind the original options (in my case I put it behind $linux_cmdline) and press Ctrl+x or F10 afterwards to boot with it.
That’s it, your window will now put you into a login shell of the coreos user and you’ll be able to curl cloud-config.