Running Environment variable at Ansible Play level question

Question

I have following commands declared in main playbook file:

---
- name: Install config
  hosts: all
  become: yes
  become_method: sudo
  become_user: root

  roles:
    - initial_config

  environment:
    http_proxy: http://{{ProxyHost}}:{{ProxyPort}}
    https_proxy: http://{{ProxyHost}}:{{ProxyPort}}
    ftp_proxy: http://{{ProxyHost}}:{{ProxyPort}}

Inside my group_vars/ all: I have declared these parameter:

ProxyHost: proxy.test.com
ProxyPort: 9999
no_proxy: 'test.com'

But I am receiving error when i run main playbook locally saying:

ERROR! Syntax Error while loading YAML.
found unexpected end of stream

Answer 1

The play below

shell> cat group_vars/all 
ProxyHost: proxy.test.com
ProxyPort: 9999
no_proxy: test.com

shell> cat pb.yml
- hosts: test_01
  environment:
    http_proxy: "http://{{ ProxyHost }}:{{ ProxyPort }}"
    https_proxy: "http://{{ ProxyHost }}:{{ ProxyPort }}"
    ftp_proxy: "http://{{ ProxyHost }}:{{ ProxyPort }}"
  tasks:
    - shell: set | grep proxy
      register: result
    - debug:
        var: result.stdout_lines

gives

shell> ansible-playbook pb.yml

PLAY [test_01] **********

TASK [shell] ************
changed: [test_01]

TASK [debug] ************
ok: [test_01] => {
    "result.stdout_lines": [
        "SUDO_COMMAND='/bin/sh -c echo BECOME-SUCCESS-hhojceebldohrrfvivcndrtjtvtrzgfg ; http_proxy=http://proxy.test.com:9999 https_proxy=http://proxy.test.com:9999 ftp_proxy=http://proxy.test.com:9999 /usr/local/bin/python3.7 /home/admin/.ansible/tmp/ansible-tmp-1588775688.2160842-43227888427690/AnsiballZ_command.py'",
        "ftp_proxy=http://proxy.test.com:9999",
        "http_proxy=http://proxy.test.com:9999",
        "https_proxy=http://proxy.test.com:9999"
    ]
}

PLAY RECAP **********
test_01: ok=2 changed=1 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0