如何通过ansible / jinja2中属性的存在来过滤列表？

Question

G'day everyone.

I have two ansible tasks like this, running over the 'workernodes' group in the inventory file:

- name: count remote files 
  find:
    paths: "{{ data_path }}"
  register: exported_files

- name: sum up number of remote files
  set_fact: 
    sum_of_exported_files: "{{ groups[ workernodes ] | map('extract', hostvars, 'exported_files') | map(attribute='matched') | sum }}"
  run_once: yes

This works fine as long as all are nodes available. But if the find-Task count not run on any of the workernodes i get in error in the sum-up task. There is no exported_files variable on for this node, so the mapping to the attribute fails.

How can i filter for the existance of the exported_files attribute in the extarcted hostvars list?

Please EnlightMe

Thanks.

Answer 1

when:添加以下内容when:子句：

when: groups[ workernodes ] | map('extract', hostvars, 'exported_files')|list|first|length > 0"

Answer 2

G'day everyone,

finally i found the (really simple) answer by myself:

sum_of_exported_files: "{{ groups[ workernodes ] | map('extract', hostvars, 'exported_files') | select("defined") | map(attribute='matched') | select("number") | sum }}"

Thanks isabellema for your thought that helped me to think it over.