Ansible Playbook - Adding entries into /etc/hosts file

Question

I am trying to read hosts from inventory file:

# PostgreSQL nodes
[all]
192.168.63.31 hostname=pgnode1
192.168.63.32 hostname=pgnode2
192.168.63.33 hostname=pgnode3

And add them to /etc/hosts file of all these nodes in the format below:

192.168.63.31 pgnode1
192.168.63.32 pgnode2
192.168.63.33 pgnode3

I have tried:

 - name: update host file
      lineinfile:
        state: present
        dest: /etc/hosts
        line: "{% for host in groups.all %} {{ host }} {{ hostvars\[host\]\['hostname'\] }} {% endfor %}"

I also tried blockinfile but it adds in this format not in separate lines:

192.168.63.32 pgnode2  192.168.63.33 pgnode3  192.168.63.31 pgnode1

I have tried whatever I could find but no luck. Please help with this. Thanks in advance.

Why did you escape the array notation in `hostvars\[host\]`? This is off course not the same as `hostvars[host]` — β.εηοιτ.βε, Jul 03 '23 at 16:19
escape characters were just typo during copy & paste. cheers — Majid Chaudhary, Jul 04 '23 at 06:39

score 0 · Accepted Answer · answered Jul 03 '23 at 16:26

I also tried blockinfile ...

A minimal example playbook

---
- hosts: localhost
  become: false
  gather_facts: false

  tasks:

  - blockinfile:
      state: present
      dest: etc_hosts
      content: |
        {% for host in groups.all %}
        {{ host }}
        {% endfor %}

will result into requested output.

... but it adds in this format not in separate lines

This is because of the format of line:. It will also work with a format like

  - lineinfile:
      state: present
      dest: etc_hosts
      line: |
        {% for host in groups.all %}
        {{ host }}
        {% endfor %}

However, the task will not be idempotent and add the lines several times.

Similar Q&A

Ansible: lineinfile for several lines?

I guess I need to search better. Thank you very much for your help. — Majid Chaudhary, Jul 04 '23 at 06:37

Ansible Playbook - Adding entries into /etc/hosts file

1 Answers1