ansible: Variable not reinitialized using a role

Question

i have a strange behaviour that i don't understand

Playbook "vars_roles.yml":

---
- hosts: localhost
  gather_facts: no
  vars:
    msg_role3: "first_run"

  roles:
    - role: role3

- hosts: localhost
  gather_facts: no
  vars:
    msg_role3: "second_run"

  roles:
    - role: role3

Content of role3 :

cat roles/role3/defaults/main.yml

---
# defaults file for role3
add_value: false
msg_role3: "default"

tab_msg:
  - "Init value: {{ msg_role3 }}"

cat roles/role3/tasks/main.yml

---
# tasks file for role3

- name: Value
  debug:
    msg: "Variable is {{ msg_role3 }}"
- name: Content of Array
  debug:
    var: tab_msg

- name: Add "value" into Array
  set_fact:
    tab_msg: "{{ (tab_msg) + [item] }}"
  loop:
    - "value: {{ msg_role3 }}"
  when: add_value | bool

- name: Content of Array after add value
  debug:
    var: tab_msg

So, my problem came from the set_fact with the list 'tab_msg: "{{ (tab_msg) + [item] }}"' if this task is played, the list "tab_msg" keep values from the first run of the role "role3"

Example without the set_fact :

ansible-playbook vars_roles.yml -e add_value=false
[WARNING]: provided hosts list is empty, only localhost is available. Note that the implicit localhost does not match 'all'

PLAY [localhost] ******************************************************************************************************************************************************

TASK [role3 : Value] **************************************************************************************************************************************************
Tuesday 27 October 2020  16:28:59 +0100 (0:00:00.055)       0:00:00.055 *******
ok: [localhost] => {
    "msg": "Variable is first_run"
}

TASK [role3 : Content of Array] ***************************************************************************************************************************************
Tuesday 27 October 2020  16:28:59 +0100 (0:00:00.053)       0:00:00.108 *******
ok: [localhost] => {
    "tab_msg": [
        "Init value: first_run"
    ]
}

TASK [role3 : Add "value" into Array] *********************************************************************************************************************************
Tuesday 27 October 2020  16:28:59 +0100 (0:00:00.052)       0:00:00.161 *******
skipping: [localhost] => (item=value: first_run)

TASK [role3 : Content of Array after add value] ***********************************************************************************************************************
Tuesday 27 October 2020  16:28:59 +0100 (0:00:00.052)       0:00:00.214 *******
ok: [localhost] => {
    "tab_msg": [
        "Init value: first_run"
    ]
}

PLAY [localhost] ******************************************************************************************************************************************************

TASK [role3 : Value] **************************************************************************************************************************************************
Tuesday 27 October 2020  16:28:59 +0100 (0:00:00.058)       0:00:00.272 *******
ok: [localhost] => {
    "msg": "Variable is second_run"
}

TASK [role3 : Content of Array] ***************************************************************************************************************************************
Tuesday 27 October 2020  16:28:59 +0100 (0:00:00.047)       0:00:00.319 *******
ok: [localhost] => {
    "tab_msg": [
        "Init value: second_run"
    ]
}

TASK [role3 : Add "value" into Array] *********************************************************************************************************************************
Tuesday 27 October 2020  16:28:59 +0100 (0:00:00.048)       0:00:00.368 *******
skipping: [localhost] => (item=value: second_run)

TASK [role3 : Content of Array after add value] ***********************************************************************************************************************
Tuesday 27 October 2020  16:28:59 +0100 (0:00:00.052)       0:00:00.420 *******
ok: [localhost] => {
    "tab_msg": [
        "Init value: second_run"
    ]
}

PLAY RECAP ************************************************************************************************************************************************************
localhost                  : ok=6    changed=0    unreachable=0    failed=0    skipped=2    rescued=0    ignored=0

Example with set_fact played :

ansible-playbook vars_roles.yml -e add_value=true
[WARNING]: provided hosts list is empty, only localhost is available. Note that the implicit localhost does not match 'all'

PLAY [localhost] ******************************************************************************************************************************************************

TASK [role3 : Value] **************************************************************************************************************************************************
Tuesday 27 October 2020  16:31:44 +0100 (0:00:00.052)       0:00:00.052 *******
ok: [localhost] => {
    "msg": "Variable is first_run"
}

TASK [role3 : Content of Array] ***************************************************************************************************************************************
Tuesday 27 October 2020  16:31:44 +0100 (0:00:00.052)       0:00:00.104 *******
ok: [localhost] => {
    "tab_msg": [
        "Init value: first_run"
    ]
}

TASK [role3 : Add "value" into Array] *********************************************************************************************************************************
Tuesday 27 October 2020  16:31:44 +0100 (0:00:00.049)       0:00:00.154 *******
ok: [localhost] => (item=value: first_run)

TASK [role3 : Content of Array after add value] ***********************************************************************************************************************
Tuesday 27 October 2020  16:31:44 +0100 (0:00:00.054)       0:00:00.208 *******
ok: [localhost] => {
    "tab_msg": [
        "Init value: first_run",
        "value: first_run"
    ]
}

PLAY [localhost] ******************************************************************************************************************************************************

TASK [role3 : Value] **************************************************************************************************************************************************
Tuesday 27 October 2020  16:31:44 +0100 (0:00:00.053)       0:00:00.262 *******
ok: [localhost] => {
    "msg": "Variable is second_run"
}

TASK [role3 : Content of Array] ***************************************************************************************************************************************
Tuesday 27 October 2020  16:31:44 +0100 (0:00:00.047)       0:00:00.309 *******
ok: [localhost] => {
    "tab_msg": [
        "Init value: first_run",
        "value: first_run"
    ]
}

TASK [role3 : Add "value" into Array] *********************************************************************************************************************************
Tuesday 27 October 2020  16:31:44 +0100 (0:00:00.047)       0:00:00.357 *******
ok: [localhost] => (item=value: second_run)

TASK [role3 : Content of Array after add value] ***********************************************************************************************************************
Tuesday 27 October 2020  16:31:44 +0100 (0:00:00.055)       0:00:00.412 *******
ok: [localhost] => {
    "tab_msg": [
        "Init value: first_run",
        "value: first_run",
        "value: second_run"
    ]
}

PLAY RECAP ************************************************************************************************************************************************************
localhost                  : ok=8    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

Any ideas ?

Thanks

Vladimir Botka Vladimir Botka · Accepted Answer · 2020-10-27T20:42:51

The result, you see, is correct. See Understanding variable precedence. Value assigned in set_fact has higher precedence (19.) than role's defaults (2.). In addition to this, the value assigned in set_fact will be available to subsequent plays during an ansible-playbook run.

In the simplified example below, set_fact (19.) has higher precedence than play vars (12.)

shell> cat pb.yml
- hosts: localhost
  vars:
    msg_role3: "first_run"
  tasks:
    - debug:
        var: msg_role3
    - set_fact:
        msg_role3: "Added value"
      when: add_value|default(false)|bool

- hosts: localhost
  vars:
    msg_role3: "second_run"
  tasks:
    - debug:
        var: msg_role3

gives (abridged)

shell> ansible-playbook pb.yml

PLAY [localhost] ****

  msg_role3: first_run

PLAY [localhost] ****

  msg_role3: second_run

shell> ansible-playbook pb.yml -e "add_value=true"

PLAY [localhost] ****

  msg_role3: first_run


PLAY [localhost] ****

  msg_role3: Added value

The solution to your problem is removing tab_msg from defaults/main.yml and putting it into the tasks/main.yml. For example

shell> cat roles/role3/defaults/main.yml
add_value: false
msg_role3: "default"

shell> cat roles/role3/tasks/main.yml
- name: Init tab_msg
  set_fact:
    tab_msg:
      - "Init value: {{ msg_role3 }}"
- name: Value
  ...

ansible: Variable not reinitialized using a role

1 Answers