ansible ssh prompt known_hosts issue

Question

I\'m running Ansible playbook and it works fine on one machine.

On a new machine when I try for the first time, I get the following error.

17:04:34          


        

Answer 1

To update local known_hosts file, I ended up using a combination of ssh-keyscan (with dig to resolve a hostname to IP address) and ansible module known_hosts as follows: (filename ssh-known_hosts.yml)

- name: Store known hosts of 'all' the hosts in the inventory file
  hosts: localhost
  connection: local

  vars:
    ssh_known_hosts_command: "ssh-keyscan -T 10"
    ssh_known_hosts_file: "{{ lookup('env','HOME') + '/.ssh/known_hosts' }}"
    ssh_known_hosts: "{{ groups['all'] }}"

  tasks:

  - name: For each host, scan for its ssh public key
    shell: "ssh-keyscan {{ item }},`dig +short {{ item }}`"
    with_items: "{{ ssh_known_hosts }}"
    register: ssh_known_host_results
    ignore_errors: yes

  - name: Add/update the public key in the '{{ ssh_known_hosts_file }}'
    known_hosts:
      name: "{{ item.item }}"
      key: "{{ item.stdout }}"
      path: "{{ ssh_known_hosts_file }}"
    with_items: "{{ ssh_known_host_results.results }}"

To execute such yml, do

ANSIBLE_HOST_KEY_CHECKING=false ansible-playbook path/to/the/yml/above/ssh-known_hosts.yml

As a result, for each host in the inventory, all supported algorithms will be added/updated in the known_hosts file under hostname,ipaddress pair record; such as

atlanta1.my.com,10.0.5.2 ecdsa-sha2-nistp256 AAAAEjZHN ... NobYTIGgtbdv3K+w=
atlanta1.my.com,10.0.5.2 ssh-rsa AAAAB3NaC1y ... JTyWisGpFeRB+VTKQ7
atlanta1.my.com,10.0.5.2 ssh-ed25519 AAAAC3NaCZD ... UteryYr
denver8.my.com,10.2.13.3 ssh-rsa AAAAB3NFC2 ... 3tGDQDSfJD
...

(Provided the inventory file looks like:

[master]
atlanta1.my.com
atlanta2.my.com

[slave]
denver1.my.com
denver8.my.com

)

As opposed to the Xiong's answer, this would properly handle the content of the known_hosts file.

This play is especially helpful if using virtualized environment where the target hosts get re-imaged (thus the ssh pub keys get changed).