Ansible: save item from nested list based on match from a separate list

Question

I'm new to ansible so i'll try to explain this as best as I can...

I have two lists created from separate json_query results. One of them contains nested lists with two related items each (vm and cluster). The other is just a list of vm's that needs to be compared against. If the vm's match, I need to use the related cluster name in an API call.

Here are sample lists:

From the above example, vm5 and vm3 are matches so I would save cluster1 and cluster2 in a list to be used in an API call using a loop. Also, we have many clusters with varying numbers of vm's on each, so actual lists can (and will) vary widely.

I have tried using ansible.builtin.set_fact with a loop but the variable only stores the last iteration. It seems that jinja2 templates might work with nested loops, but I don't know how to store the variable for future use in later API calls.

Vladimir Botka · Accepted Answer · 2025-05-02 16:19:01Z

1

Given the data

data:
  - - [vm3, cluster1]
    - [vm5, cluster2]
    - [vm9, cluster3]
  - - [vm5]
    - [vm1]
    - [vm3]

Create the dictionary

vc: "{{ dict(data.0) }}"

gives

vc:
  vm3: cluster1
  vm5: cluster2
  vm9: cluster3

and the list of vm(s) in the dictionary

vm: "{{ data.1 | flatten | select('in', vc) }}"

gives

vm: [vm5, vm3]

Extract the result

result: "{{ vm | map('extract', vc) }}"

gives

result: [cluster2, cluster1]

^{Example of a complete playbook for testing
- hosts: localhost

vars:

data:
- - [vm3, cluster1]
- [vm5, cluster2]
- [vm9, cluster3]
- - [vm5]
- [vm1]
- [vm3]
vc: "{{ dict(data.0) }}"
vm: "{{ data.1 | flatten | select('in', vc) }}"
result: "{{ vm | map('extract', vc) }}"

tasks:

- debug:
var: vc | to_nice_yaml
- debug:
var: vm | to_yaml
- debug:
var: result | to_yaml}

edited May 2 at 16:19

answered May 2 at 2:57

Vladimir Botka

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1 Comment

dhubert27 May 2 at 14:32

Thank you, Vladimir, this works perfectly. I had not worked with dictionaries before; I clearly have much to learn.

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