CoreOS Authentication failure on vagrant up

Question

I tried using CoreOS today. So I just tried to follow the Start guide and executed the following commands:

git clone https://github.com/coreos/coreos-vagrant.git

cd coreos-vagrant

vagrant up

The coreos-vagrant's folder have some configuration resource like: config.rb & user-data

config.rb :

$update_channel='alpha'

user-data:

#cloud-config

coreos:
  etcd:
    addr: $public_ipv4:4001
    peer-addr: $public_ipv4:7001
  fleet:
    public-ip: $public_ipv4
  units:
    - name: etcd.service
      command: start
    - name: fleet.service
      command: start

users:
  - name: carbonell
    passwd: $1$BulVX1y9$8W/3RHZAed3fb.wmbZYGi0
    groups:
      - docker

The command result:

devops@devops-server:~/workspace/coreos-vagrant$ vagrant up
Bringing machine 'core-01' up with 'virtualbox' provider...
==> core-01: Importing base box 'coreos-alpha'...
==> core-01: Matching MAC address for NAT networking...
==> core-01: Setting the name of the VM: coreos-vagrant_core-01_1405929178704_22375
==> core-01: Clearing any previously set network interfaces...
==> core-01: Preparing network interfaces based on configuration...
    core-01: Adapter 1: nat
    core-01: Adapter 2: hostonly
==> core-01: Forwarding ports...
    core-01: 22 => 2222 (adapter 1)
==> core-01: Running 'pre-boot' VM customizations...
==> core-01: Booting VM...
==> core-01: Waiting for machine to boot. This may take a few minutes...
    core-01: SSH address: 127.0.0.1:2222
    core-01: SSH username: vagrant
    core-01: SSH auth method: private key
    core-01: Warning: Connection timeout. Retrying...
    core-01: Warning: Authentication failure. Retrying...
    core-01: Warning: Authentication failure. Retrying...
    core-01: Warning: Authentication failure. Retrying...
    core-01: Warning: Authentication failure. Retrying...
    core-01: Warning: Authentication failure. Retrying...
    core-01: Warning: Authentication failure. Retrying...
    core-01: Warning: Authentication failure. Retrying...
    core-01: Warning: Authentication failure. Retrying...
    core-01: Warning: Authentication failure. Retrying...
    core-01: Warning: Authentication failure. Retrying...
    core-01: Warning: Authentication failure. Retrying...
    core-01: Warning: Authentication failure. Retrying...
    core-01: Warning: Authentication failure. Retrying...
    core-01: Warning: Authentication failure. Retrying...
    core-01: Warning: Authentication failure. Retrying...
    core-01: Warning: Authentication failure. Retrying...
    core-01: Warning: Authentication failure. Retrying...
    core-01: Warning: Authentication failure. Retrying...
    core-01: Warning: Authentication failure. Retrying...
    core-01: Warning: Authentication failure. Retrying...
    core-01: Warning: Authentication failure. Retrying...
    core-01: Warning: Authentication failure. Retrying...
    core-01: Warning: Authentication failure. Retrying...
    core-01: Warning: Authentication failure. Retrying...
    core-01: Warning: Authentication failure. Retrying...
    core-01: Warning: Authentication failure. Retrying...
    core-01: Warning: Authentication failure. Retrying...
    core-01: Warning: Authentication failure. Retrying...
    core-01: Warning: Authentication failure. Retrying...
Timed out while waiting for the machine to boot. This means that
Vagrant was unable to communicate with the guest machine within
the configured ("config.vm.boot_timeout" value) time period.

If you look above, you should be able to see the error(s) that
Vagrant had when attempting to connect to the machine. These errors
are usually good hints as to what may be wrong.

If you're using a custom box, make sure that networking is properly
working and you're able to connect to the machine. It is a common
problem that networking isn't setup properly in these boxes.
Verify that authentication configurations are also setup properly,
as well.

Secondary reference: https://github.com/coreos/coreos-vagrant.git

Answer 1

Did you add the ssh key for Vagrant?

$ ssh-add ~/.vagrant.d/insecure_private_key
Identity added: /Users/core/.vagrant.d/insecure_private_key (/Users/core/.vagrant.d/insecure_private_key)
$ vagrant ssh core-01 -- -A

reference: http://coreos.com/docs/quickstart/

Answer 2

Vagrant has a feature for replacing the insecure private key when starting:

core-01: 
core-01: Vagrant insecure key detected. Vagrant will automatically replace
core-01: this with a newly generated keypair for better security.
core-01: 
core-01: Inserting generated public key within guest...
core-01: Removing insecure key from the guest if its present...
core-01: Key inserted! Disconnecting and reconnecting using new SSH key...

however somehow on CoreOS the replaced private key gets lost on vagrant reload, so what helps is to delete the machine private key, e.i.

rm .vagrant/machines/core-01/virtualbox/private_key