Subtract date from Jinja expression - date

Question

I want to remove 1 month from current_date_operation in Ansible task. This is what I tried:
vars:
# for example current
current_date_operation: "{{ ansible_date_time.date }}"
previous_date_operation : "{{ '%Y-%m-%d'|strftime(current_date_operation.epoch|int - 2592000) }}"
Unfortunately, the above code is giving the following error:
"msg": "The task includes an option with an undefined variable. The error was: 'ansible.utils.unsafe_proxy.AnsibleUnsafeText object' has no attribute 'epoch'
Any idea?
Thanks

Answer 1

In your vars declaration, your are first getting the date key from object ansible_date_time.
On the next line, you are using that set variable (which is a string) and call on it the key epoch which does not exists as it is a property of the parent object (i.e. ansible_date_time). Since your var declaration cannot be parsed correctly, the var in itself is undefined.
The following playbook demonstrate you can get the expected result by fixing your vars definition:
---
- hosts: localhost
vars:
current_date_operation: "{{ ansible_date_time.date }}"
previous_date_operation : "{{ '%Y-%m-%d' | strftime(ansible_date_time.epoch | int - 2592000) }}"
tasks:
- debug:
var: current_date_operation
- debug:
var: previous_date_operation
Test run:
$ ansible-playbook playbook.yml
PLAY [localhost] **************************************************************************************************************************************************************************************************
TASK [Gathering Facts] ********************************************************************************************************************************************************************************************
ok: [localhost]
TASK [debug] ******************************************************************************************************************************************************************************************************
ok: [localhost] => {
"current_date_operation": "2020-01-14"
}
TASK [debug] ******************************************************************************************************************************************************************************************************
ok: [localhost] => {
"previous_date_operation": "2019-12-15"
}
PLAY RECAP ********************************************************************************************************************************************************************************************************
localhost : ok=3 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0