jinja2 templates can only yield strings

[pablobm]

ISSUE TYPE

• Bug Report

COMPONENT NAME

• Evaluation of jinja2 templates

ANSIBLE VERSION

$ ansible --version
ansible 2.1.2.0
  config file =
  configured module search path = Default w/o overrides

OS / ENVIRONMENT

N/A (assumed. Only tested on macOS)

SUMMARY

You can't have non-string variables as the result of arithmetic/filters/etc in jinja2 templates

STEPS TO REPRODUCE

Consider a playbook and a vars file:

# test_vars.yml
seven: 7
seven_again: "{{ seven }}"
seven_once_more: "{{ seven | int }}"
fourteen: "{{ (seven * 2) | int }}"

# test.yml
- hosts: all
  gather_facts: False
  vars_files:
    - test_vars.yml
  tasks:
    - debug:
        msg: "{{ seven | to_json}} {{ seven_again | to_json }} {{ seven_once_more | to_json }} {{ fourteen | to_json }}"

EXPECTED RESULTS

I would have expected all four numbers to appear unquoted, as follows (abridged):

$ ansible-playbook test.yml -i localhost, -c local -vvv
(...)
ok: [localhost] => {
    "msg": "7 7 7 14"
}
(...)

ACTUAL RESULTS

Instead, the last two numbers are quoted, as follows (abridged):

$ ansible-playbook test.yml -i localhost, -c local -vvv
(...)
ok: [localhost] => {
    "msg": "7 7 \"7\" \"14\""
}
(...)

[melankh]

Hi,
This bug affect us too.

# ansible --version
ansible 2.2.0.0
  config file = /etc/ansible/ansible.cfg
  configured module search path = ['/usr/share/ansible']
# uname -a
Linux xxxxxxxx   2.6.32-642.6.2.el6.x86_64 #1 SMP Wed Oct 26 06:52:09 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

[alikins]

(Mentioning #17992 here to keep track of related issues)

[ansibot]

cc @dharmabumstead
click here for bot help

[dagwieers]

There is a light at the end of the tunnel. We made a change to Jinja2 so we don't see all variable types changed into strings. See: pallets/jinja#708

[mkrizek]

This behavior can be altered with the following config option (turned off by default) https://docs.ansible.com/ansible/devel/reference_appendices/config.html#default-jinja2-native which will be included in the 2.7 release.