Using Ansible set_fact to create a dictionary from register results
AnsibleAnsible Problem Overview
In Ansible I've used register
to save the results of a task in the variable people
. Omitting the stuff I don't need, it has this structure:
{
"results": [
{
"item": {
"name": "Bob"
},
"stdout": "male"
},
{
"item": {
"name": "Thelma"
},
"stdout": "female"
}
]
}
I'd like to use a subsequent set_fact
task to generate a new variable with a dictionary like this:
{
"Bob": "male",
"Thelma": "female"
}
I guess this might be possible but I'm going round in circles with no luck so far.
Ansible Solutions
Solution 1 - Ansible
I think I got there in the end.
The task is like this:
- name: Populate genders
set_fact:
genders: "{{ genders|default({}) | combine( {item.item.name: item.stdout} ) }}"
with_items: "{{ people.results }}"
It loops through each of the dicts (item
) in the people.results
array, each time creating a new dict like {Bob: "male"}
, and combine()
s that new dict in the genders
array, which ends up like:
{
"Bob": "male",
"Thelma": "female"
}
It assumes the keys (the name
in this case) will be unique.
I then realised I actually wanted a list of dictionaries, as it seems much easier to loop through using with_items
:
- name: Populate genders
set_fact:
genders: "{{ genders|default([]) + [ {'name': item.item.name, 'gender': item.stdout} ] }}"
with_items: "{{ people.results }}"
This keeps combining the existing list with a list containing a single dict. We end up with a genders
array like this:
[ {'name': 'Bob', 'gender': 'male'}, {'name': 'Thelma', 'gender': 'female'}]
Solution 2 - Ansible
Thank you Phil for your solution; in case someone ever gets in the same situation as me, here is a (more complex) variant:
---
# this is just to avoid a call to |default on each iteration
- set_fact:
postconf_d: {}
- name: 'get postfix default configuration'
command: 'postconf -d'
register: command
# the answer of the command give a list of lines such as:
# "key = value" or "key =" when the value is null
- name: 'set postfix default configuration as fact'
set_fact:
postconf_d: >
{{
postconf_d |
combine(
dict([ item.partition('=')[::2]|map('trim') ])
)
with_items: command.stdout_lines
This will give the following output (stripped for the example):
"postconf_d": {
"alias_database": "hash:/etc/aliases",
"alias_maps": "hash:/etc/aliases, nis:mail.aliases",
"allow_min_user": "no",
"allow_percent_hack": "yes"
}
Going even further, parse the lists in the 'value':
- name: 'set postfix default configuration as fact'
set_fact:
postconf_d: >-
{% set key, val = item.partition('=')[::2]|map('trim') -%}
{% if ',' in val -%}
{% set val = val.split(',')|map('trim')|list -%}
{% endif -%}
{{ postfix_default_main_cf | combine({key: val}) }}
with_items: command.stdout_lines
...
"postconf_d": {
"alias_database": "hash:/etc/aliases",
"alias_maps": [
"hash:/etc/aliases",
"nis:mail.aliases"
],
"allow_min_user": "no",
"allow_percent_hack": "yes"
}
A few things to notice:
-
in this case it's needed to "trim" everything (using the
>-
in YAML and-%}
in Jinja), otherwise you'll get an error like:FAILED! => {"failed": true, "msg": "|combine expects dictionaries, got u\" {u'...
-
obviously the
{% if ..
is far from bullet-proof -
in the postfix case,
val.split(',')|map('trim')|list
could have been simplified toval.split(', ')
, but I wanted to point out the fact you will need to|list
otherwise you'll get an error like:"|combine expects dictionaries, got u\"{u'...': <generator object do_map at ...
Hope this can help.