Ansible: insert a single word on an existing line in a file

Question

I have to use Ansible modules in order to edit the /etc/ssh/sshd_config file - every time I create a new user I want to append it at these two lines:

AllowUs         


        

Answer 1

The replace module will replace all instances of a regular expression pattern within a file. Write a task to match the AllowUsers line and replace it with the original line appended with the user name. To ensure the task is idempotent, a negative lookahead assertion in the regular expression checks if the user name already appears in the line. For example:

- name: Add user to AllowUsers
  replace:
    backup: yes
    dest: /etc/ssh/sshd_config
    regexp: '^(AllowUsers(?!.*\b{{ user_name }}\b).*)$'
    replace: '\1 {{ user_name }}'