set_facts with dict as argument of a loop - list

Question

I'd like to obtain the list of bridged interfaces grouped by master like this:
brv100:
- vnet0
- eth0
brv101:
- vnet1
- eth1
I want to use native json output from the shell commands.
The only thing I managed to do is to get a predefined number of interfaces like this:
- hosts: localhost
gather_facts: no
tasks:
- shell:
cmd: ip -details -pretty -json link show type bridge
register: list_bridges
- set_fact:
bridges: "{{ list_bridges.stdout }}"
- debug:
msg: "{{ bridges | map(attribute='ifname') | list}}"
- name: get json
shell:
cmd: ip -details -pretty -json link show master "{{ifname}}"
with_items: "{{bridges | map(attribute='ifname') | list}}"
loop_control:
loop_var: ifname
register: list_interfaces
- set_fact:
interfaces: "{{ list_interfaces.results | map(attribute='stdout') | list }}"
- set_fact:
toto: "{{interfaces.1}} + {{interfaces.2}}"
- debug:
msg: "{{toto | map(attribute='ifname')|list}}"
Now if I want to do the same with a loop :
- set_fact:
toto: " {{item|default([])}}+ {{ item |default([])}}.{{idx}} "
loop: "{{interfaces}}"
loop_control:
label: "{{item}}"
index_var: idx
- debug: var=toto
The result doesn't seem to be a list of list, but a list of strings and I can't extract the 'ifname' values with a simple debug
- debug:
msg: "{{toto | map(attribute='ifname')|list}}"
What am I supposed to do so as to get benefit of the json native output and get simple list of bridged interfaces (like brctl show was used to do)?

Answer 1

The lists of bridged interfaces grouped by the master are available in ansible_facts. The task below sets the dictionary of the bridges and bridged interfaces
- set_fact:
bridges: "{{ dict(ansible_facts|
dict2items|
json_query('[?value.type == `bridge`].[key, value.interfaces]')) }}"
Q: "Manage to get the same result manipulating JSON data."
A: The output of the ip -json ... command is JSON formated string which must be converted to JSON dictionary in Ansible by the from_yaml filter (JSON is a subset of YAML). For example, the tasks below give the same result
vars:
my_debug: false
tasks:
- name: Get bridges names
command: "ip -details -json link show type bridge"
register: list_bridges
- set_fact:
bridges: "{{ list_bridges.stdout|
from_yaml|
map(attribute='ifname')|
list }}"
- debug:
var: bridges
when: my_debug
- name: Get bridges interfaces
command: "ip -details -json link show master {{ item }}"
loop: "{{ bridges }}"
register: list_interfaces
- set_fact:
bridges_interfaces: "{{ list_interfaces.results|
json_query('[].stdout')|
map('from_yaml')|
list }}"
- debug:
msg: "{{ msg.split('\n') }}"
vars:
msg: "{{ item|to_nice_yaml }}"
loop: "{{ bridges_interfaces }}"
loop_control:
label: "{{ item|json_query('[].ifname') }}"
when: my_debug
- name: Set dictionary of bridges
set_fact:
bridges_dict: "{{ bridges_dict|
default({})|
combine({item.0: item.1|json_query('[].ifname')}) }}"
loop: "{{ bridges|zip(bridges_interfaces)|list }}"
loop_control:
label: "{{ item.1|json_query('[].ifname') }}"
- debug:
var: bridges_dict
Template to write the bridges to a file
{% for k,v in bridges_dict.items() %}
{{ k }}:
{% if v is iterable %}
{% for i in v %}
- {{ i }}
{% endfor %}
{% endif %}
{% endfor %}
- name: Write the bridges to file
template:
src: bridges.txt.j2
dest: bridges.txt
The file bridges.txt will be created in the remote host running the task.