How to do it...

1.  On the Ansible machine, create the private and public SSH keys in our ch3_junos working directory, as shown in the following code:

$ SSH-keygen -t rsa -b 2048 -f Ansible_SSH_key

Generating public/private rsa key pair.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in Ansible_SSH_key.
Your public key has been saved in Ansible_SSH_key.pub.
The key fingerprint is:
SHA256:aCqgMYKAWIkv3nVz/q9cYp+2n3doD9jpgw/jeWWcVWI Ansible@centos7.localdomain

2. Capture the public key that was created in the previous step, as follows:

$ cat Ansible_SSH_key.pub
 SSH-rsa SSH-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC0/wvdC5ycAanRorlfMYDMAv5OTcYAALlE2bdboajsQPQNEw1Li3N0J50OJBWXX+FFQuF7JKpM32vNQjQN7BgyaBWQGxv+Nj0ViVP+8X8Wuif0m6bFxBYSaPbIbGogDjPu4qU90Iv48NGOZpcPLqZthtuN7yZKPshX/0YJtXd2quUsVhzVpJnncXZMb4DZQeOin7+JVRRrDz6KP6meIylf35mhG3CV5VqpoMjYTzkDiHwIrFWVMydd4C77RQu27N2HozUtZgJy9KD8qIJYVdP6skzvp49IdInwhjOA+CugFQuhYhHSoQxRxpws5RZlvrN7/0h0Ahc3OwHaUWD+P7lz Ansible@centos7.localdomain

3. On the Juniper devices, add a new user called admin and designate that we will use SSH keys for authentication for this user. Copy the public SSH key that was created on the Ansible machine to the device, as shown in the following code:

[edit system login]
Ansible@mxpe01# show
user admin {
  uid 2001;
  class super-user;
  authentication {
    SSH-rsa " SSH-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC0/wvdC5ycAanRorlfMYDMAv5OTcYAALlE2bdboajsQPQNEw1Li3N0J50OJBWXX+FFQuF7JKpM32vNQjQN7BgyaBWQGxv+Nj0ViVP+8X8Wuif0m6bFxBYSaPbIbGogDjPu4qU90Iv48NGOZpcPLqZthtuN7yZKPshX/0YJtXd2quUsVhzVpJnncXZMb4DZQeOin7+JVRRrDz6KP6meIylf35mhG3CV5VqpoMjYTzkDiHwIrFWVMydd4C77RQu27N2HozUtZgJy9KD8qIJYVdP6skzvp49IdInwhjOA+CugFQuhYhHSoQxRxpws5RZlvrN7/0h0Ahc3OwHaUWD+P7lz Ansible@centos7.localdomain"; ## SECRET-DATA
  }
}