Skip Ansible task when variable not defined

Question

I have the following task in a playbook:

- name: task xyz  
  copy:  
    src="{{ item }}"  
    dest="/tmp/{{ item }}"  
  with_items: "{{ y.z }}"  
  when: y.z is defined

y.z is not defined, so I'm expecting the task to be skipped. Instead, I receive:

FAILED! => {"failed": true, "msg": "'dict object' has no attribute 'z'"

I have found: How to run a task when variable is undefined in ansible? but it seems I implemented just that. What am I doing wrong here?

I don't know if the lack of an existing attribute z in the y dict is the same as y.z being undefined. Undefined does not necessarily mean the same thing as, say, null, empty, nil, false, etc. — Matthew Schuchard
– Matthew Schuchard, Commented Nov 4, 2016 at 14:24
as a different way to check, you could try 'z' not in y (i know that does not answer yout question but it could keep you going. — user2599522
– user2599522, Commented Nov 4, 2016 at 14:46
Do you mean to try 'z' in y? In any case, I tried both, but the result was the same. — jdoestackoverflow
– jdoestackoverflow, Commented Nov 4, 2016 at 14:57

techraf · Accepted Answer · 2017-02-28 05:50:52Z

8

The problem here is that with_items is evaluated before when. Actually in real scenarios you put item in the when conditional. See: Loops and Conditionals.

This task will work for you:

- name: task xyz
  copy:  
    src: "{{ item }}"  
    dest: "/tmp/{{ item }}"  
  with_items: "{{ (y|default([])).z | default([]) }}"

edited Feb 28, 2017 at 5:50

answered Nov 4, 2016 at 14:52

techraf

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3 Comments

jdoestackoverflow Over a year ago

Referring to the documentation for completeness: "Combining when with with_items (see Loops), be aware that the when statement is processed separately for each item." (docs.ansible.com/ansible/playbooks_conditionals.html)

techraf Over a year ago

I'm not sure what you mean by your comment. I included a direct link to the statement you cited in my answer.

jdoestackoverflow Over a year ago

Ah, somehow missed it. You're correct, your answer was already as complete as can be.

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