Overrride cloud-config parameters installed by coreos-install

If you invested a lot of time to override config param that comes through installation, then carry on reading.

The installation script will process your cloud-config.yaml file specified with the -c flag and place it onto disk. It will be installed to /var/lib/coreos-install/user_data and evaluated on every boot.

For instance,  there is a simple config for coreos-install

#cloud-config

coreos:

  etcd:

    name: node001

    addr: 192.168.100.1:4001

    peer-addr: 192.168.100.1:7001

    discovery: <discoveriy ip>

  units:

    - name: etcd.service

      command: start

There are two way to override config parameter:

1. Override systemd service by etcd.service.d/override.conf:
2. Override coreos installation script under /var/lib/coreos-install/user_data

I prefer to edit /var/lib/coreos-install/user_data and run coreos-cloudinit to update configurations.