[root@localhost dev]# yum install ansible -y

## green.example.com
## blue.example.com
192.168.0.101
192.168.0.102
[webservers]
## alpha.example.org
## beta.example.org
192.168.0.101
192.168.0.102

[root@localhost ansible]# ansible 192.168.0.101 -m ping -k
SSH password:
192.168.0.101 | SUCCESS => {
  "changed": false,
  "ping": "pong"
}
[root@localhost ansible]# ansible webservers -m ping -k
SSH password:
192.168.0.102 | FAILED! => {
  "msg": "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."
}
192.168.0.101 | SUCCESS => {
  "changed": false,
  "ping": "pong"
}

[root@localhost home]# ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa):
/root/.ssh/id_rsa already exists.
Overwrite (y/n)? y
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
SHA256:9/pGNxnQVWAWpss7PYtJcUDyHsCexgYY6NGWy/oOhTg root@localhost.localdomain
The key's randomart image is:
+---[RSA 2048]----+
|   o.+ .o ..*++|
|  o = . .=.=. |
|  . + . + .=.  |
|  ...o  *o +. |
| E ... So. = .o |
|  ...  . ..=+ |
|  ..   .=.o. |
|   ..  o.+ o |
|   ..  .o+ . |
+----[SHA256]-----+

[root@localhost ~]# ssh-copy-id -i /root/.ssh/id_rsa.pub root@192.168.0.102
/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/root/.ssh/id_rsa.pub"
/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
/usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys
Kernel \r on an \m
root@192.168.0.102's password:
Number of key(s) added: 1
Now try logging into the machine, with:  "ssh 'root@192.168.0.102'"
and check to make sure that only the key(s) you wanted were added.