add SSH role

This will for now only disable ssh password logins, when the variable
ssh_disable_password_login is set to yes.

all.yml

@@ -4,3 +4,4 @@
     - users
     - autoupdate
     - revproxy
+    - ssh

host_vars/revproxy-05.freifunk-stuttgart.de/ssh

+---
+ssh_disable_password_login: yes

roles/ssh/defaults/main.yml

+---
+ssh_disable_password_login: no

roles/ssh/handlers/main.yml

+---
+- name: restart ssh
+  service: 
+    name: ssh
+    state: restarted
+

roles/ssh/tasks/main.yml

+---
+- name: Disable SSH password login
+  lineinfile:
+    regexp: "^#?PasswordAuthentication"
+    line: "PasswordAuthentication no"
+    path: /etc/ssh/sshd_config
+  notify:
+    - restart ssh
+  when: ssh_disable_password_login