Ansible playbook to install SSH host keys in known_hosts

host-keys.yml

# Ansible playbook that installs host keys for all of my servers into ~/.ssh/known_hosts
# group_vars/all has to list them all like
#
# ssh_host_keys:
#   github: |
#     github.com ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAq2A7hRGmdnm9tUDbO9IDSwBK6TbQa+PXYPCPy6rbTrTtw7PHkccKrpp0yVhp5HdEIcKr6pLlVDBfOLX9QUsyCOV0wzfjIJNlGEYsdlLJizHhbn2mUjvSAHQqZETYP81eFzLQNnPHt4EVVUh7VfDESU84KezmD5QlWpXLmvU31/yMf+Se8xhHTvKSCZIFImWwoG6mbUoWf9nzpIoaSjB+weqqUUmpaaasXVal72J+UX2B+2RPW3RcT0eOzQgqlJL3RKrTJvdsjE3JEAvGq3lGHSZXy28G3skua2SmVi/w4yCE6gbODqnTWlg7+wC604ydGXA8VJiS5ap43JXiUFFAaQ==
#   fridge: |
#     fridge.pov.lt ssh-dss ...
#     fridge.pov.lt ssh-rsa ...
#
# You can get the keys themselves by doing cat /etc/ssh/ssh_host*_key.pub on each server

- hosts: localhost
  gather_facts: no
  tasks:
    - name: set up ~/.ssh/known_hosts
      lineinfile:
        dest: ~/.ssh/known_hosts
        line:  "{{ item }}"
        create: yes
      with_items: "{{ ''.join(ssh_host_keys.values()).splitlines()|sort }}"