Dynamicly set HTTP_PROXY in an ansible playbook

I'm running a playbook either on a bunch of servers with no need of http_proxy and others with needs of it (on different runs).

I've read https://docs.ansible.com/ansible/latest/user_guide/playbooks_environment.html but it doesn't really answer this...

here's an example:

- hosts: all tasks: - name: install vi become: true apt: name: vi state: present

I would like to launch it with a group of servers (let's say server01-atlanta) without proxy and in another run with a group of servers (let's say server01-berlin) with proxy and without changing the code between each run (so managing to do it with inventory variables).

I would

Solution

You can solve this with group_vars / host_vars in combination with environment variables. Her is a simple example based on the code from ansible docs.

---
- hosts: all
  vars:
    proxy: # default empty
  tasks:    
    - apt: name=cobbler state=installed
      environment:
        http_proxy: "{{ proxy }}"

This is how you define a environment variable per task. You can also use normal ansible variables for this. There is also a example with proxy settings and variables in the docs. See: https://docs.ansible.com/ansible/latest/user_guide/playbooks_environment.html

In your inventory you can define the proxy variable per host or group:

atlanta:
  hosts:
    host1:
    host2:
  vars:
    proxy: proxy.atlanta.example.com

See inventory docs for more details: https://docs.ansible.com/ansible/latest/user_guide/intro_inventory.html#host-variables