Problem when dynamically constructing dict variables with string list as values

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SUMMARY

When dynamically creating a dict var with a list as its value, it’s working when the list elements are int but will fallback to a string when the list elements are strings.

ISSUE TYPE
  • Not sure if this is a bug in Ansible, YAML or Jinja2, or is a feature by design
COMPONENT NAME

n/a

ANSIBLE VERSION
2.7.0
OS / ENVIRONMENT
Linux awx 3.10.0-862.14.4.el7.x86_64 #1 SMP Wed Sep 26 15:12:11 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

(Ansible AWX 2.0.1 official docker image)

STEPS TO REPRODUCE

The points are:

  1. the dict’s key has to be dynamic with vars passed at runtime
  2. the dict’s value has to be a string list

A sample play:

- name: Dynamically construct dict with string list and pass to some role
hosts: test
remote_user: tester
become: no
roles:
- role: some_role
variables: "{
'{{ dynamic_key }}_KEY': '{{ [\"value1\"] + [\"value2\"] }}'
}"

With the above play, variables we got in some_role is as follows when give it var1 for dynamic_key:

ok: [test] => {
"variables": "{ 'var1_KEY': '['value1', 'value2']' }"
}

where both the templating of dynamic_key and list concatenating worked as expected, but the dict became a string as a whole. However, if we change the two lists into integer lists, it will work fine:

input:

- name: Dynamically construct dict with int list and pass to some role
hosts: test
remote_user: tester
become: no
roles:
- role: some_role
variables: "{
'{{ dynamic_key }}_KEY': '{{ [1,2,3] + [4,5,6] }}'
}"

output:

ok: [test] => {
"variables": {
"var1_KEY": "[1, 2, 3, 4, 5, 6]"
}
}

in this case, the whole dict are constructed correctly. I would like to know if this is a feature by design or a bug.

Maybe some of you may ask why I don’t construct and pass the variables like this:

- name: Dynamically construct dict with int list and pass to some role
hosts: test
remote_user: tester
become: no
roles:
- role: some_role
variables:
"{{ dynamic_key }}_KEY": "{{ [1,2,3] + [4,5,6] }}"

The reason is the “{{ dynamic_key }}_KEY” won’t get templated and will be kept as {{ dynamic_key }}_KEY in the result. I don’t know either this is a feature or a bug.

I hope I have described everything clearly. Thanks!

EXPECTED RESULTS

as above mentioned

ACTUAL RESULTS

as above mentionedEnter code here…