Manage environment variables

[Stefano]

I need set the environment variable to build some app at startup, i use vars in the playbook file:

---
- hosts: all
  sudo: yes
  vars:
    build_env:
      VAR1: value1
      VAR2: value2
      VAR3: value3
 

And set with environment into task to build app

- name: Build app
  environment: "{{build_env}}"
  command: "{{ item }} chdir={{app1}}"
  with_items:
  - npm install
  - bower
  - gulp
 

Also i need add the same variables to /etc/environment but i would not replicate the  variables in another task, any idea?