How can I use Ansible nested variable? - ansible

Question

I have an Ansible playbook like the one below, I want use nested variable like this:
msg={{{{Component}}.community_release_num}}, but when I run playbook:
ansible-playbook vartest.yml -e 'version=version_402', it not work
[es#vpn-server nested-var]$ tree
.
├── vars
│   ├── horizon.yml
│   └── version_402.yml
└── vartest.yml
1 directory, 3 files
[es#vpn-server nested-var]$ cat vartest.yml
---
- name: test
hosts: localhost
vars_files:
- vars/{{version}}.yml
tasks:
- debug: msg={{{{Component}}.community_release_num}}
- debug: msg={{{{Component}}.release_num}}
[es#vpn-server nested-var]$ cat vars/horizon.yml
Component: horizon
[es#vpn-server nested-var]$ cat vars/version_402.yml
- horizon:
community_release_num: '9.0.1'
release_num: '4.0.2'
[es#vpn-server nested-var]$
error messages
[es#vpn-server nested-var]$ ansible-playbook vartest.yml -e 'version=version_402'
/usr/lib64/python2.6/site-packages/cryptography/__init__.py:25: DeprecationWarning: Python 2.6 is no longer supported by the Python core team, please upgrade your Python.
DeprecationWarning
PLAY [test] *******************************************************************************************************
/usr/lib64/python2.6/site-packages/Crypto/Util/number.py:57: PowmInsecureWarning: Not using mpz_powm_sec. You should rebuild using libgmp >= 5 to avoid timing attack vulnerability.
_warn("Not using mpz_powm_sec. You should rebuild using libgmp >= 5 to avoid timing attack vulnerability.", PowmInsecureWarning)
TASK [debug] ******************************************************************************************************
fatal: [localhost]: FAILED! => {"failed": true, "msg": "template error while templating string: expected token 'colon', got '}'. String: {{{{Component}}.community_release_num}}"}
to retry, use: --limit #/data/wangqian/artemis-code-test/artemis/ansible/update/nested-var/vartest.retry
PLAY RECAP ********************************************************************************************************
localhost : ok=0 changed=0 unreachable=0 failed=1
Can Ansible use nested variable, if yes, how to use it?

Answer 1

Per Ansible FAQ:
Another rule is ‘moustaches don’t stack’. We often see this:
{{ somevar_{{other_var}} }}
The above DOES NOT WORK, if you need to use a dynamic variable use the
hostvars or vars dictionary as appropriate:
{{ hostvars[inventory_hostname]['somevar_' + other_var] }}
So in your case:
- debug: msg={{hostvars[inventory_hostname][Component].community_release_num}}
Or:
- debug: msg={{vars[Component].community_release_num}}
Or (since Ansible 2.5):
- debug: msg={{(lookup('vars', Component)).community_release_num}}

Answer 2

Run this command:
ansible-playbook 1_lambda-facts.yml -e "func_name=mylambdaFunctionName"
- name: get lamda Info
hosts: localhost
connection: local
become: yes
gather_facts: true
tasks:
- name: List all for a specific function
lambda_facts:
query: all
function_name: "{{func_name}}"
- name: debug info
debug:
msg: "{{lambda_facts}}"
msg: "variable name is: {{vars['func_name']}}"
msg: "{{lambda_facts['function'][vars['func_name']]['function_arn']}}"