Read an environment variable - Ansible lookup plugin env

How to automate the reading of HOME environmental variable and use it in your Ansible Playbook code with lookup plugin env.

February 18, 2022

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#ansible #lookup #plugin #env #linux #posix

How to read an environment variable on Ansible Controller with Ansible?

I’m going to show you a live demo with some simple Ansible code. I’m Luca Berton and welcome to today’s episode of Ansible Pilot.

Ansible read an environment variable

ansible.builtin.env
Read the value of environment variables

Let’s deep dive into the Ansible lookup plugin env. Plugins are a way to expand the Ansible functionality. With lookup plugins specifically, you can load variables or templates with information from external sources. The full name is ansible.builtin.env, it’s part of ansible-core and is included in all Ansible installations. The purpose of the env lookup plugin is to read the value of environment variables.

Parameters and Return Value

Parameters

_terms string - Environment variable

Return Values

_raw list - Values from the environment variables

The parameters of plugin env.

The only required parameter is the default “_terms”, with the name of the environment variable to read. The normal usage is to assign the lookup plugin to a variable name but you could use it in your Ansible task directly.

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demo

Read an environment variable with Ansible Playbook.

code

---
- name: environment demo
  hosts: all
  tasks:
    - name: display HOME
      ansible.builtin.debug:
        msg: "{{ lookup('env', 'HOME') }}"

execution

ansible-pilot $ printenv | grep HOME
HOME=/Users/lberton
ansible-pilot $ ansible-playbook -i virtualmachines/demo/inventory ansible\ statements/environment.yml
PLAY [environment demo] ***************************************************************************
TASK [Gathering Facts] ****************************************************************************
ok: [demo.example.com]
TASK [display HOME] *******************************************************************************
ok: [demo.example.com] => {
    "msg": "/Users/lberton"
}
PLAY RECAP ****************************************************************************************
demo.example.com           : ok=2    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0
ansible-pilot $

idempotency

ansible-pilot $ printenv | grep HOME
HOME=/Users/lberton
ansible-pilot $ ansible-playbook -i virtualmachines/demo/inventory ansible\ statements/environment.yml
PLAY [environment demo] ***************************************************************************
TASK [Gathering Facts] ****************************************************************************
ok: [demo.example.com]
TASK [display HOME] *******************************************************************************
ok: [demo.example.com] => {
    "msg": "/Users/lberton"
}
PLAY RECAP ****************************************************************************************
demo.example.com           : ok=2    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0
ansible-pilot $