Ansible : appending data of file using template module

Question

Is there a way to append data using a template module in ansible. There are options for lineinfile and blockinfile in ansible. But I have to append data to the host's file. I want to preserve original hosts and add new hosts to the existing file.

Answer 1

When using the template module, a complete file is templated.

What you could do is dynamically build your file in a way like this in the Jinja2 template:

This is content of my file, not being replaced.

{% for item in some_variable %}
{% {{ item }} %}
{% endfor %}

 And here is the end of the file, not being replaced.

However, it feels like you're trying to edit a /etc/hosts file or something similar. You shouldn't use template for this use case.

Using lineinfile is perfect for those scenarios. Try something along the lines of:

  - name: Add the hosts names and IPs to /etc/hosts
    lineinfile:
      dest: /etc/hosts
      regexp: '.*{{ item }}$'
      line: "{{ hostvars[item]['ansible_default_ipv4']['address'] }} {{item}}"
    state: present
    when: hostvars[item]['ansible_facts']['default_ipv4'] is defined
    with_items:
      - "{{ groups['all'] }}"

Answer 2

You can use blockinfile to accomplish above as below:

- name: Add the below DNS records
  blockinfile:
   path: /etc/hosts
   marker: "------"
   insertafter: '^yourlinepattern'
   state: present
   block: |
      lines to append