ansible get the interface name by providing an IP address

Question

I have two interfaces in machine(linux). One interface has been addressed and second is down without any IP. Now I would like to get the interface name matched with IP what I provide as value in ansible.

I was trying something like this:

    - name: interface name from provides IP
  set_fact:
    interface_name="{{ item }}"
  with_items:
     - "{{ ansible_interfaces | map('replace', '-','_') | list }}"
  when: hostvars[ansible_fqdn]['ansible_'~item]['ipv4']['address'] == PROVIDED_IP

It works good when all interfaces have IP address but problem is when one interface has no IP then I have error: 'dict object' has no attribute 'ipv4'

Is possible to get interface name without getting errors?

Answer 1

try this playbook, just set the IP you want to search for:

- hosts: localhost
  gather_facts: true
  vars:
    desired_interface_name: ""
    target_interface_name: "192.168.16.200"

  tasks:
    - name: parse interfaces
      set_fact:
        desired_interface_name="{{ item }}"
      when: hostvars[inventory_hostname]['ansible_{{item}}']['ipv4']['address'] == target_interface_name
      with_items:
        - "{{ ansible_interfaces }}"

    - name: print result
      debug:
        var: desired_interface_name

Answer 2

You can do this using jinja:

- name: Get interface name from provided IP
  set_fact:
    interface_name: "{{ ansible_interfaces | map('regex_replace', '^', 'ansible_') | map('extract', vars) | selectattr('ipv4.address', 'match', '192\\.168\\.16\\.200') | map(attribute='device') | first }}"

{{ ansible_interfaces | map('regex_replace', '^', 'ansible_') | map('extract', vars) gets you a list of interfaces, where each interface is a dictionary with information about the interface. You can then filter and map the list to get what you need.