CODEWITHSUNDEEP
ansible
lubik
lubik

Reputation: 79

How ansible assign values to variables?

Let's have a playbook:

---
- name: testplaybook
  hosts: 127.0.0.1
  connection: local
  become: yes
  vars:
    x: 'latest'
    y: '{{x.split("-SNAPSHOT")[0]}}'
  tasks:
  - name: 1st debug x, y
    debug:
      msg: 'x={{x}}, y={{y}}'
  - set_fact: x='1.0.1-SNAPSHOT'
  - name: 2nd debug x, y
    debug:
      msg: 'x={{x}}, y={{y}}'

The output is:

TASK [1st debug x, y] 
**************************************************************
task path: /var/tmp/test_ansible/testPlaybook.yml:17
ok: [127.0.0.1] => {
    "msg": "x=latest, y=latest"
}

TASK [set_fact] 
****************************************************************
task path: /var/tmp/test_ansible/testPlaybook.yml:20
ok: [127.0.0.1] => {"ansible_facts": {"x": "1.0.1-SNAPSHOT"}, "changed": false}

TASK [2nd debug x, y] 
**********************************************************
task path: /var/tmp/test_ansible/testPlaybook.yml:21
ok: [127.0.0.1] => {
    "msg": "x=1.0.1-SNAPSHOT, y=1.0.1"
}

The question is, why y is changed.

When does ansible assign values to variables and does it do a reassignment in particular cases?

Upvotes: 0

Views: 694

Answers (2)

Jack
Jack

Reputation: 6158

You have set y to be a string, which is {{x.split("-SNAPSHOT")[0]}}.

Only when you actually USE the variable does all the de-referencing occur.

Upvotes: 0

larsks
larsks

Reputation: 311238

The value of y hasn't changed. The value of y is a Jinja template expression, {{x.split("-SNAPSHOT")[0]}}. Ansible performs lazy evaluation of these expressions, so this is evaluated whenver you use y. Since the value of the expression is dependent on x, it will evaluate to a new value if you change x.

Upvotes: 2

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