[ansible] How to set host_key_checking=false in ansible inventory file?

I would like to use ansible-playbook command instead of 'vagrant provision'. However setting host_key_checking=false in the hosts file does not seem to work.

# hosts file
vagrant ansible_ssh_private_key_file=~/.vagrant.d/insecure_private_key 
ansible_ssh_user=vagrant ansible_ssh_port=2222 ansible_ssh_host=127.0.0.1 
host_key_checking=false

Is there a configuration variable outside of Vagrantfile that can override this value?

I could not use:

ansible_ssh_common_args='-o StrictHostKeyChecking=no'

in inventory file. It seems ansible does not consider this option in my case (ansible 2.0.1.0 from pip in ubuntu 14.04)

I decided to use:

server ansible_host=192.168.1.1 ansible_ssh_common_args= '-o UserKnownHostsFile=/dev/null'

It helped me.

Also you could set this variable in group instead for each host:

[servers_group:vars]
ansible_ssh_common_args='-o UserKnownHostsFile=/dev/null'

Yes, you can set this on the inventory/host level.

^{With an already accepted answer present, I think this is a better answer to the question on how to handle this on the inventory level. I consider this more secure by isolating this insecure setting to the hosts required for this (e.g. test systems, local development machines).}

What you can do at the inventory level is add

ansible_ssh_common_args='-o StrictHostKeyChecking=no'

or

ansible_ssh_extra_args='-o StrictHostKeyChecking=no'

to your host definition (see Ansible Behavioral Inventory Parameters).

This will work provided you use the ssh connection type, not paramiko or something else).

For example, a Vagrant host definition would look like…

vagrant ansible_port=2222 ansible_host=127.0.0.1 ansible_ssh_common_args='-o StrictHostKeyChecking=no'

or

vagrant ansible_port=2222 ansible_host=127.0.0.1 ansible_ssh_extra_args='-o StrictHostKeyChecking=no'

Running Ansible will then be successful without changing any environment variable.

$ ansible vagrant -i <path/to/hosts/file> -m ping
vagrant | SUCCESS => {
    "changed": false, 
    "ping": "pong"
}

In case you want to do this for a group of hosts, here's a suggestion to make it a supplemental group var for an existing group like this:

[mytestsystems]
test[01:99].example.tld

[insecuressh:children]
mytestsystems

[insecuressh:vars]
ansible_ssh_common_args='-o StrictHostKeyChecking=no'

Adding following to ansible config worked while using ansible ad-hoc commands:

[ssh_connection]
# ssh arguments to use
ssh_args = -o StrictHostKeyChecking=no

Ansible Version

ansible 2.1.6.0
config file = /etc/ansible/ansible.cfg

You set these configs either in the /etc/ansible/ansible.cfg or ~/.ansible.cfg or ansible.cfg(in your current directory) file

[ssh_connection]
ssh_args = -C -o ControlMaster=auto -o ControlPersist=60s -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no

tested with ansible 2.9.6 in ubuntu 20.04

In /etc/ansible/ansible.cfg uncomment the line:

host_key_check = False

and in /etc/ansible/hosts uncomment the line

client_ansible ansible_ssh_host=10.1.1.1 ansible_ssh_user=root ansible_ssh_pass=12345678

That's all