Ansible example which shows how to reach nested variable with dynamic elements

ansible-nested-variable.yml

# Example which shows how to reach nested ansible variable which is partially different.
# Run that plabook with ansible-playbook -e "env=test" ansible-nested-variable.yml
---
# 
- hosts: localhost
  connection : ssh
  gather_facts: no
  vars:
    cidr_blocks:
      vpc_production_cidr_block: "10.10.0.0/28"
      vpc_infra_cidr_block:      "10.20.0.0/28"
      vpc_test_cidr_block:       "10.30.0.0/28"

  tasks:

    - name: Show all CIDRs
      debug:
        msg: "{{ cidr_blocks}}"

    - name: Show spesific CIDRs
      debug:
        msg: "{{ cidr_blocks['vpc_%s_cidr_block' | format(env)] }}" # Be careful about position of square brackets.

Nicely done! Thanks for sharing.

If use python string function format() instead jinja filter, we dont need be careful with position of square brackets.
msg: "{{ cidr_blocks['vpc_{env}_cidr_block'.format(env=env)] }}"

If use python string function format() instead jinja filter, we dont need be careful with position of square brackets.
msg: "{{ cidr_blocks['vpc_{env_cidr_block'.format(env=env)] }}"

Good to know thanks @metajiji