How do I test in a var matches against a list of substrings in ansible? - ansible

Question

I am fairly new to ansible and I am trying to determine how to test is a variable passed to my playbook matches against a list of substrings.
I have tried something like the following. Looping through my list of badcmds and then testing whether it is in the variable passed.
vars:
badcmds:
- clear
- no
tasks:
- name: validate input
debug:
msg: " {{ item }}"
when: item in my_command
with_items: "{{ badcmds }}"
I am getting the following error:
"msg": "The conditional check 'item in my_command' failed.
The error was: Unexpected templating type error occurred on
({% if item in my_command %} True {% else %} False {% endif %}):
coercing to Unicode: need string or buffer, bool found
Many thanks.

Answer 1

one problem with your playbook is that - no is automatically translated to boolean false. you should use "no" to make Ansible consider the variable as a string. without quotes:
---
- hosts: localhost
connection: local
gather_facts: false
vars:
badcmds:
- clear
- no
my_command: clear
tasks:
- name: print variable
debug:
msg: "{{ item }}"
with_items:
- "{{ badcmds }}"
output:
TASK [print variable] ***********************************************************************************************************************************************************************************************
ok: [localhost] => (item=None) => {
"msg": "clear"
}
ok: [localhost] => (item=None) => {
"msg": false
}
I guess you should enclose no in quotes, because this behavior was not your intention.
to make a loop and check if the variable matches any item from the badcmds list, you can use:
---
- hosts: localhost
connection: local
gather_facts: false
vars:
badcmds:
- "clear"
- "no"
tasks:
- name: validate input
debug:
msg: "{{ item }}"
when: item == my_command
with_items:
- "{{ badcmds }}"
hope it helps