Validate your cloud-config file or lose access

Learned this the hard way:

I had been validating my config by eye after validating using instructions here

https://www.binarysludge.com/2015/01/28/validate-a-coreos-cloud-config-file/

BUT YOU MUST DO THIS EVERY TIME YOU MAKE A CHANGE

coreos-cloudinit -validate --from-file cloud-config.yaml

then cp cloud-config.yaml /var/lib/coreos-install/user_data