Passing an Ansible variable from one role to another

Question

In an Ansible playbook, I have a first role that creates 3 VMs in a cloud platform, and a second role that performs several setup tasks on each VM. I need to pass each VM IP address from role 1 to role 2.

This is my inventory hosts file

[masters]
master.domain.tld

[workers]
worker1.domain.tld
worker2.domain.tld

[all:vars]
ansible_user=root
ansible_ssh_private_key_file=~/.ssh/id_rsa

So far I managed to register and then extract each VM IP using this code:

......
register: hcloud_info
 
- debug:
    msg: 'Hcloud IP address is {{ item.hcloud_server.ipv4_address }}'
  with_items: "{{ hcloud_info.results }}"

The 3 IPs are properly displayed.

To pass the VM IPs from role 1 to role 2, I'm using an in-memory inventory using the add_host directive:

- name: Add new servers to dynamic inventory
  add_host:
    name: "{{ item.hcloud_server.ipv4_address }}"
    groups: new_servers
  with_items: "{{ hcloud_info.results }}"

Now in the second role, I would need to access data in the in-memory inventory to pull out each single VM's public IP and assign it ( delegate_to: SERVER_PUBLIC_IP ) to each server using this snippet:

- name: Apply private IP to master
  hcloud_server_network:
    api_token: "{{ hcloud_token }}"
    network: priv_network
    server: master.domain.tld
    ip: 10.1.0.2
    state: present
  delegate_to: SERVER_PUBLIC_IP

I've been trying to use this code in role 1, to pass it to role 2, but a 'hcloud_server' has no attribute error shows up...

- Name: Display IPs
  debug: msg="{{ item.hcloud_server.ipv4_address }}"
  with_items: "{{ groups.new_servers }}"

Answer 1

For example, get the IPs of the hosts (you take it from hcloud_info )

- hosts: workers
  gather_facts: true
  tasks:
  - debug:
      var: ansible_all_ipv4_addresses|first

ok: [worker1.domain.tld] => 
  ansible_all_ipv4_addresses|first: 10.1.0.61
ok: [worker2.domain.tld] => 
  ansible_all_ipv4_addresses|first: 10.1.0.62

In the 1st role create a dictionary of the IP addresses (fit the expression _ip to your needs)

shell> cat roles/create-vm/tasks/main.yml
- set_fact:
    my_ip: "{{ dict(ansible_play_batch|zip(_ip)) }}"
  vars:
    _ip: "{{ ansible_play_batch|
             map('extract', hostvars, 'ansible_all_ipv4_addresses')|
             map('first')|
             list }}"
  run_once: true

gives

  my_ip:
    worker1.domain.tld: 10.1.0.61
    worker2.domain.tld: 10.1.0.62

Use this dictionary in the 2nd role

shell> cat roles/apply-ip-to-master/tasks/main.yml
- debug:
    msg: "Apply {{ my_ip[inventory_hostname] }} to master"

Create a playbook

- hosts: workers
  gather_facts: true
  roles:
    - create-vm
    - apply-ip-to-master

gives

ok: [worker1.domain.tld] => 
  msg: Apply 10.1.0.61 to master
ok: [worker2.domain.tld] => 
  msg: Apply 10.1.0.62 to master

This way you can "Apply private IP to master" for each worker instead of delegating the task.