Ansible provisioning ERROR! Using a SSH password instead of a key is not possible

I would like to provision with my three nodes from the last one by using Ansible.

My host machine is Windows 10.

My Vagrantfile looks like:

Vagrant.configure("2") do |config|

  (1..3).each do |index|
    config.vm.define "node#{index}" do |node|

      node.vm.box = "ubuntu"
      node.vm.box = "../boxes/ubuntu_base.box"

      node.vm.network :private_network, ip: "192.168.10.#{10 + index}"

      if index == 3
        node.vm.provision :setup, type: :ansible_local do |ansible|
          ansible.playbook = "playbook.yml"
          ansible.provisioning_path = "/vagrant/ansible"
          ansible.inventory_path = "/vagrant/ansible/hosts"
          ansible.limit = :all
          ansible.install_mode = :pip
          ansible.version = "2.0"
        end
      end

    end
  end

end

My playbook looks like:

---

# my little playbook

- name: My little playbook
  hosts: webservers
  gather_facts: false
  roles:
    - create_user

My hosts file looks like:

[webservers]
192.168.10.11
192.168.10.12

[dbservers]
192.168.10.11
192.168.10.13

[all:vars]
ansible_connection=ssh
ansible_ssh_user=vagrant
ansible_ssh_pass=vagrant

After executing vagrant up --provision I got the following error:

Bringing machine 'node1' up with 'virtualbox' provider...
Bringing machine 'node2' up with 'virtualbox' provider...
Bringing machine 'node3' up with 'virtualbox' provider...
==> node3: Running provisioner: setup (ansible_local)...
    node3: Running ansible-playbook...

PLAY [My little playbook] ******************************************************

TASK [create_user : Create group] **********************************************
fatal: [192.168.10.11]: FAILED! => {"failed": true, "msg": "ERROR! Using a SSH password instead of a key is not possible because Host Key checking is enabled and sshpass does not support this.  Please add this host's fingerprint to your known_hosts file to manage this host."}
fatal: [192.168.10.12]: FAILED! => {"failed": true, "msg": "ERROR! Using a SSH password instead of a key is not possible because Host Key checking is enabled and sshpass does not support this.  Please add this host's fingerprint to your known_hosts file to manage this host."}

PLAY RECAP *********************************************************************
192.168.10.11              : ok=0    changed=0    unreachable=0    failed=1
192.168.10.12              : ok=0    changed=0    unreachable=0    failed=1

Ansible failed to complete successfully. Any error output should be
visible above. Please fix these errors and try again.

I extended my Vagrantfile with ansible.limit = :all and added [all:vars] to the hostfile, but still cannot get through the error.

Has anyone encountered the same issue?

Create a file ansible/ansible.cfg in your project directory (i.e. ansible.cfg in the provisioning_path on the target) with the following contents:

[defaults]
host_key_checking = false

---

^{provided that your Vagrant box has sshpass already installed - it's unclear, because the error message in your question suggests it was installed (otherwise it would be "ERROR! to use the 'ssh' connection type with passwords, you must install the sshpass program"), but in your answer you add it explicitly (sudo apt-get install sshpass), like it was not}