Read custom variable from ansible Host File in playbook - ansible

Question

I am trying to read some custom variables created in Ansible host file, but i am not able to read it somehow and it is throwing exception
Hostfile
[webserver]
xx.xx.45.12 uname=abc123
xx.xx.45.13 uname=pqr456
Playbook yaml
- name: sample playbook
hosts: all
tasks:
- name: sample echo command
shell:
cmd: echo {{hostvars['all'].uname}}
I couldn't find any document which is talking clearly how to read host variable
When i am running above I am getting below error.
fatal: [xx.xx.45.12]: FAILED! => {"msg": "The task includes an option with an undefined variable.
The error was: \"hostvars['webserver']\" is undefined\n\nThe error appears to be in
'/mnt/c/Users/ManishBansal/Documents/work/MSS/scripts/run.yaml': line 6, column 7, but may\nbe elsewhere
in the file depending on the exact syntax problem.\n\nThe offending line appears to be:\n\n tasks:\n
- name: This command will get file list\n ^ here\n"}

Answer 1

Q: "How to read host variable?"
A: Simply reference the variable
- command: echo {{ uname }}
For example the inventory and the playbook below
shell> cat hosts
[webserver]
test_01 uname=abc123
test_02 uname=pqr456
shell> cat playbook.yml
- hosts: all
tasks:
- debug:
var: uname
give (abridged)
shell> ansible-playbook -i hosts playbook.yml
ok: [test_01] =>
uname: abc123
ok: [test_02] =>
uname: pqr456
Use hostvars to reference variables registered with other hosts. For example
shell> cat playbook.yml
- hosts: localhost
tasks:
- debug:
var: hostvars[item].uname
loop: "{{ groups.webserver }}"
gives (abridged)
shell> ansible-playbook -i hosts playbook.yml
ok: [localhost] => (item=test_01) =>
ansible_loop_var: item
hostvars[item].uname: abc123
item: test_01
ok: [localhost] => (item=test_02) =>
ansible_loop_var: item
hostvars[item].uname: pqr456
item: test_02
Notes
See Caching facts
Quoting from module shell notes
"... it may be better to use the command module instead ..."