Ansible loops for assigning sequential integers as hostnames - linux

Question

I'm new to Ansible. I have the following playbook that changes the hostname for a remote server:
---
- hosts: dbservers
remote_user: testuser1
become: yes
become_method: sudo
vars:
LOCAL_HOSTNAME: 'db01'
LOCAL_DOMAIN_NAME: 'ansibletest.com'
tasks:
# Checks and removed the existing occurences of <IP hostname FQDN> from /etc/hosts
- name: Remove occurences of the existing IP
lineinfile: dest=/etc/hosts
regexp='{{ hostvars[item].ansible_default_ipv4.address }}'
state=absent
when: hostvars[item].ansible_default_ipv4.address is defined
with_items: "{{ groups['dbservers'] }}"
# Adds the IP in the format <IP hostname FQDN> to /etc/hosts
- name: Add the IP and hostname to the hosts file
lineinfile: dest=/etc/hosts
regexp='.*{{ item }}$'
line="{{ hostvars[item].ansible_default_ipv4.address }} {{ LOCAL_HOSTNAME }} {{ LOCAL_HOSTNAME }}.{{ LOCAL_DOMAIN_NAME }}"
state=present
when: hostvars[item].ansible_default_ipv4.address is defined
with_items: "{{ groups['dbservers'] }}"
- name: Remove HOSTNAME occurences from /etc/sysconfig/network
lineinfile: dest=/etc/sysconfig/network
regexp='^HOSTNAME'
state=absent
when: hostvars[item].ansible_default_ipv4.address is defined
with_items: "{{ groups['dbservers'] }}"
- name: Add new HOSTNAME to /etc/sysconfig/network
lineinfile: dest=/etc/sysconfig/network
regexp='^HOSTNAME='
line="HOSTNAME={{ LOCAL_HOSTNAME }}.{{ LOCAL_DOMAIN_NAME }}"
state=present
when: hostvars[item].ansible_default_ipv4.address is defined
with_items: "{{ groups['dbservers'] }}"
- name: Set up the hostname
hostname: name={{ LOCAL_HOSTNAME }}.{{ LOCAL_DOMAIN_NAME }}
In this example, LOCAL_HOSTNAME is already assigned a value of db01. And in this scenario, the dbservers group has only one server:
[dbservers]
192.168.1.93
However, I also have 2 other servers that are designated to be webservers:
[webservers]
192.168.1.95
192.168.1.96
[dbservers]
192.168.1.93
The aim is to name them as web01.domain, web02.domain and so on.
As per the docs it seems that this could be achieved by using with_sequence.
My question is, is it possible (in Ansible) to use 2 variables in loops? Something along the lines of the pseudo-code below:
i=1
for host in webservers:
open host(/etc/hosts):
add "IP<space>HOSTNAME{i}<space>"<space>"HOSTNAME{i}.FQDN"
i++
Could this be achieved using playbooks or am I approaching the issue in an wrong way?

Answer 1

Generate indexed hostname first, define it as hostfact and use it later to fill other servers' hosts files.
- hosts: webservers
gather_facts: no
tasks:
- set_fact:
indexed_hostname: "{{ 'web{0:02d}'.format(play_hosts.index(inventory_hostname)+1) }}"
- hosts: dbservers
gather_facts: no
tasks:
- debug:
msg: "{{ hostvars[item].indexed_hostname }}"
with_items: "{{ groups['webservers'] }}"
Also there is such thing as with_indexed_items.