Deploying ssh keys with Ansible

Ansible allows us to perform practically any type of configuration. In this case, we will add our pubkey to the authorized_keys of several servers. This is really useful if the group of sysadmins varies a lot, so to remove access from one of them, we only need to modify the authorized file locally and redeploy.

We create the necessary directories for Ansible:

mkdir /etc/ansible/
chown -R root:kr0m /etc/ansible/
chmod 775 /etc/ansible/

We create a group of servers called test:

vi /etc/ansible/hosts

[test]
SERVER1
SERVER2

We create the playbook that will add the pubkeys to the test group servers in the usertest user:

vi AuthorizedKeys.yml

- hosts: test
  tasks:
    - name: SysAdmin authorized_keys
      authorized_key:
        user: usertest
        state: present
        exclusive: yes
        manage_dir: yes
        key: "{{ lookup('file', '/home/kr0m/sysadmin.pub') }}"

Podemos ver todas las opciones en este enlace , el parámetro mas importante es exclusive: yes que nos permite NO apendear las keys si no que solo pushea las que haya en el fichero de keys.

Añadimos las keys al fichero:

vi /home/kr0m/sysadmin.pub

ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDVQnniSdSbjmAtjMfLpj5hjTRz8Xr/5pn7G43cznRXSQ3zCG6QvEqNEOxVkMfvDx+esIaINrecyD388l9gctqrXb13kE7JxQZnXW6rnJcCG96r006nR1sz7bXrj0OGRBIag53MK4fX1MhkJi6bsV4JiOEBB5bnnDvD1YuuO6zEPIl58w4h21JI7R78Zg9nWwAyNBgJsaCq4kyt1g4GpRtil00V0GERMfyKaS3CcjvSHMQKNR8INzW+BCo8KIZCUXdgl7h4qjo0064/1tCWNo6Yv1gtnjxK3nWo6AaC9Cno58RCb0FuRg+GS5LGQuKRXH8NdTYl4KG4usrtfSbO6pCf kr0m@skynet
ssh-rsa AAAAB3HZZaC5hd2T5kAAAADAQABAAABAQDVQnniSdSbjmAtjMfLpj5hjTRz8Xr/5pn7G43cznRXSQ3zCG6QvEqNEOxVkMfvDx+esIaINrecyD388l9gctqrXb13kE7JxQZnXW6rnJcCG96r006nR1sz7bXrj0OGRBIag53MK4fX1MhkJi6bsV4JiOEBB5bnnDvD1YuuO6zEPIl58w4h21JI7R78Zg9nWwAyNBgJsaCq4kyt1g4GpRtil00V0GERMfyKaS3CcjvSHMQKNR8INzW+BCo8KIZCUXdgl7h4qjo0064/1tCWNo6Yv1gtnjxK3nWo6AaC9Cno58RCb0FuRg+GS5LGQuKRXH8NdTYl4KG4usrtfSbO6pCf sysadmin2@host

We access the two servers and add the user:

ssh SERVER1/SERVER2
adduser usertest

We run the playbook:

ansible-playbook AuthorizedKeys.yml

We check that it has been executed correctly:

root@SERVER1:~# cat /home/usertest/.ssh/authorized_keys
ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDVQnniSdSbjmAtjMfLpj5hjTRz8Xr/5pn7G43cznRXSQ3zCG6QvEqNEOxVkMfvDx+esIaINrecyD388l9gctqrXb13kE7JxQZnXW6rnJcCG96r006nR1sz7bXrj0OGRBIag53MK4fX1MhkJi6bsV4JiOEBB5bnnDvD1YuuO6zEPIl58w4h21JI7R78Zg9nWwAyNBgJsaCq4kyt1g4GpRtil00V0GERMfyKaS3CcjvSHMQKNR8INzW+BCo8KIZCUXdgl7h4qjo0064/1tCWNo6Yv1gtnjxK3nWo6AaC9Cno58RCb0FuRg+GS5LGQuKRXH8NdTYl4KG4usrtfSbO6pCf kr0m@skynet
ssh-rsa AAAAB3HZZaC5hd2T5kAAAADAQABAAABAQDVQnniSdSbjmAtjMfLpj5hjTRz8Xr/5pn7G43cznRXSQ3zCG6QvEqNEOxVkMfvDx+esIaINrecyD388l9gctqrXb13kE7JxQZnXW6rnJcCG96r006nR1sz7bXrj0OGRBIag53MK4fX1MhkJi6bsV4JiOEBB5bnnDvD1YuuO6zEPIl58w4h21JI7R78Zg9nWwAyNBgJsaCq4kyt1g4GpRtil00V0GERMfyKaS3CcjvSHMQKNR8INzW+BCo8KIZCUXdgl7h4qjo0064/1tCWNo6Yv1gtnjxK3nWo6AaC9Cno58RCb0FuRg+GS5LGQuKRXH8NdTYl4KG4usrtfSbO6pCf sysadmin2@host

root@SERVER2:~# cat /home/usertest/.ssh/authorized_keys
ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDVQnniSdSbjmAtjMfLpj5hjTRz8Xr/5pn7G43cznRXSQ3zCG6QvEqNEOxVkMfvDx+esIaINrecyD388l9gctqrXb13kE7JxQZnXW6rnJcCG96r006nR1sz7bXrj0OGRBIag53MK4fX1MhkJi6bsV4JiOEBB5bnnDvD1YuuO6zEPIl58w4h21JI7R78Zg9nWwAyNBgJsaCq4kyt1g4GpRtil00V0GERMfyKaS3CcjvSHMQKNR8INzW+BCo8KIZCUXdgl7h4qjo0064/1tCWNo6Yv1gtnjxK3nWo6AaC9Cno58RCb0FuRg+GS5LGQuKRXH8NdTYl4KG4usrtfSbO6pCf kr0m@skynet
ssh-rsa AAAAB3HZZaC5hd2T5kAAAADAQABAAABAQDVQnniSdSbjmAtjMfLpj5hjTRz8Xr/5pn7G43cznRXSQ3zCG6QvEqNEOxVkMfvDx+esIaINrecyD388l9gctqrXb13kE7JxQZnXW6rnJcCG96r006nR1sz7bXrj0OGRBIag53MK4fX1MhkJi6bsV4JiOEBB5bnnDvD1YuuO6zEPIl58w4h21JI7R78Zg9nWwAyNBgJsaCq4kyt1g4GpRtil00V0GERMfyKaS3CcjvSHMQKNR8INzW+BCo8KIZCUXdgl7h4qjo0064/1tCWNo6Yv1gtnjxK3nWo6AaC9Cno58RCb0FuRg+GS5LGQuKRXH8NdTYl4KG4usrtfSbO6pCf sysadmin2@host