# How to retrieve fact with a dynamic fact name? **URL:** \ **Category:** Get Help\ **Created:** [September 6, 2025, 6:20pm UTC](https://forum.ansible.com/t/how-to-retrieve-fact-with-a-dynamic-fact-name/44431 "2025-09-06T18:20:19Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![matthew\_exon](https://avatars.discourse-cdn.com/v4/letter/m/edb3f5/32.png) [@matthew\_exon](https://forum.ansible.com/u/matthew_exon)\ **Post date:** [September 6, 2025, 6:20pm UTC](https://forum.ansible.com/t/how-to-retrieve-fact-with-a-dynamic-fact-name/44431/1 "2025-09-06T18:20:19Z")
I’m trying to call out to a task list with `include_tasks` where I want the task list to set a particular named fact, passed as a variable to the task list. I can set the fact, but it’s not appearing in `ansible_facts` as I would expect. Here’s a playbook with five tasks: 1. Sets the fact according to a fact name passed as a variable 2. Retrieves the fact, proving it’s set 3. Gets a fact from `ansible_facts`, showing how I expect that to work 4. Gets the fact by name, which doesn’t work as I expect 5. Gets the fact according to a fact name passed as a variable, what I’m trying to achieve Can someone explain why step 4 doesn’t work, and how it should be done? ``` --- - hosts: all tasks: - name: Set first fact with dynamic fact name ansible.builtin.set_fact: {"{{ fact_name }}":"hello world"} vars: fact_name: "fact1" - name: Get first fact as variable - WORKS ansible.builtin.debug: var: fact1 - name: Get processor cores from ansible_facts - WORKS ansible.builtin.debug: var: ansible_facts["processor_cores"] - name: Get first fact from ansible_facts - DOESN'T WORK ansible.builtin.debug: var: ansible_facts["fact1"] - name: Get first fact from ansible_facts with dynamic fact name - DOESN'T WORK ansible.builtin.debug: var: ansible_facts[fact_name] vars: fact_name: "fact1" ``` ---
**Author:** ![felixfontein](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/felixfontein/32/7530_2.png) [@felixfontein](https://forum.ansible.com/u/felixfontein)\ **Post date:** [September 6, 2025, 6:29pm UTC](https://forum.ansible.com/t/how-to-retrieve-fact-with-a-dynamic-fact-name/44431/2 "2025-09-06T18:29:46Z")
The reason is that `ansible.builtin.set_fact` does not create facts, but variables (more precisely: host-level variables) with a fixed value. The same happens if you don’t use a dynamic fact name, but a static fact name. You can fix that by making it a cacheable fact by setting `cacheable=true`, which will create a host-level variable _and_ a “real” Ansible fact: ```auto - name: Set first fact with dynamic fact name ansible.builtin.set_fact: "{{ fact_name }}": hello world cacheable: true vars: fact_name: "fact1" ``` See [ansible.builtin.set\_fact module – Set host variable(s) and fact(s). — Ansible Community Documentation](https://docs.ansible.com/ansible/devel/collections/ansible/builtin/set_fact_module.html#parameter-cacheable) for more infos. ---
**Author:** ![matthew\_exon](https://avatars.discourse-cdn.com/v4/letter/m/edb3f5/32.png) [@matthew\_exon](https://forum.ansible.com/u/matthew_exon)\ **Post date:** [September 6, 2025, 6:51pm UTC](https://forum.ansible.com/t/how-to-retrieve-fact-with-a-dynamic-fact-name/44431/3 "2025-09-06T18:51:09Z")
Thanks! I saw `cacheable: true` and could see that it was something important, but I couldn’t make head or tail of the explanation. 7 levels of precedence sounds like acute demonology. I used your example and now I made it all go the way I wanted. > The reason is that `ansible.builtin.set_fact` does not create facts, but variables Perhaps it should be called `set_variable`, and have an option `set_fact: true`? Or, if that can’t work for demonology-related reasons, perhaps a slightly simpler warning in the docs? ---
**Author:** ![felixfontein](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/felixfontein/32/7530_2.png) [@felixfontein](https://forum.ansible.com/u/felixfontein)\ **Post date:** [September 7, 2025, 2:32pm UTC](https://forum.ansible.com/t/how-to-retrieve-fact-with-a-dynamic-fact-name/44431/4 "2025-09-07T14:32:45Z")
Well, to be honest, I wasn’t really aware of this behavior before myself, since I always used `set_fact` as a sort of “set variable to a constant value” (as opposed to `vars`, which sets them to something that’s evaluated on every usage). I agree that `set_variable` would be a better name, but I guess the naming comes from the early history of Ansible and hasn’t been changed since it’s used everywhere. ---
**Author:** ![bcoca](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/bcoca/32/9269_2.png) [@bcoca](https://forum.ansible.com/u/bcoca)\ **Post date:** [September 8, 2025, 1:51pm UTC](https://forum.ansible.com/t/how-to-retrieve-fact-with-a-dynamic-fact-name/44431/5 "2025-09-08T13:51:48Z")
> [@felixfontein](#): > > ally aware of this behavior before myself, since I always used `set_fact` as a sort of “set variabl There is an irc log somewhere with a 3 week flame war about naming `set_fact` (originally `set_var` IIRC) ---
**Author:** ![anon81884396](https://avatars.discourse-cdn.com/v4/letter/a/b782af/32.png) [@anon81884396](https://forum.ansible.com/u/anon81884396)\ **Post date:** [September 8, 2025, 3:42pm UTC](https://forum.ansible.com/t/how-to-retrieve-fact-with-a-dynamic-fact-name/44431/6 "2025-09-08T15:42:48Z")
> Perhaps it should be called `set_variable` , and have an option `set_fact: true` ? Please don’t give them any ideas ☹ Seagulls are called seagulls despite them not being exclusively tied to the sea, humanity moves on and doesn’t need to rewrite every piece of literature in existence for correctness sake. I say this with peace and love, of course! ---
**Author:** ![bcoca](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/bcoca/32/9269_2.png) [@bcoca](https://forum.ansible.com/u/bcoca)\ **Post date:** [September 8, 2025, 3:46pm UTC](https://forum.ansible.com/t/how-to-retrieve-fact-with-a-dynamic-fact-name/44431/7 "2025-09-08T15:46:55Z")
my proposal looong ago was: ```auto set_var: value=x scope=host|play|fact ``` ---
**Author:** ![matthew\_exon](https://avatars.discourse-cdn.com/v4/letter/m/edb3f5/32.png) [@matthew\_exon](https://forum.ansible.com/u/matthew_exon)\ **Post date:** [September 10, 2025, 5:22am UTC](https://forum.ansible.com/t/how-to-retrieve-fact-with-a-dynamic-fact-name/44431/8 "2025-09-10T05:22:28Z")
In my particular case, I wanted a way to set a “thing” (fact, variable, don’t mind) with a name string and retrieve it with the same name string. Having an `ansible_vars` array similar to `ansible_facts` would have worked just as well. But I couldn’t find anything like that. Seems like there’s a surprising asymmetry there. ---
**Author:** ![utoddl](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/utoddl/32/249_2.png) [@utoddl](https://forum.ansible.com/u/utoddl)\ **Post date:** [September 10, 2025, 11:01am UTC](https://forum.ansible.com/t/how-to-retrieve-fact-with-a-dynamic-fact-name/44431/9 "2025-09-10T11:01:29Z")
You can do what you want if you make the dynamic part not a top-level variable. Instead, store the dynamic names as keys in a known named dict. Consider this playbook: ```yaml --- # matthew_exon_00.yml - name: Dynamic fact name hosts: localhost gather_facts: false tasks: - name: Initialize our dynamic fact store ansible.builtin.set_fact: dyn_fact_store: {} - name: Add some dynamic facts ansible.builtin.set_fact: dyn_fact_store: '{{ dyn_fact_store | combine({dname: dvalue}) }}' vars: dvalue: '{{ 100 | ansible.builtin.random }}' loop: ['apple', 'banana', 'grape'] loop_control: loop_var: dname - name: Dump our dynamic fact store ansible.builtin.debug: var: dyn_fact_store ``` which produces this (varies from run to run of course): ```plaintext TASK [Dump our dynamic fact store] **** ok: [localhost] => { "dyn_fact_store": { "apple": "73", "banana": "18", "grape": "10" } } ``` These aren’t really _facts_ as felixfontein pointed out, unless you also set `cacheable: true` and enable caching . ---
**Author:** ![matthew\_exon](https://avatars.discourse-cdn.com/v4/letter/m/edb3f5/32.png) [@matthew\_exon](https://forum.ansible.com/u/matthew_exon)\ **Post date:** [September 10, 2025, 11:17am UTC](https://forum.ansible.com/t/how-to-retrieve-fact-with-a-dynamic-fact-name/44431/10 "2025-09-10T11:17:35Z")
Yes, this is probably cleaner. Still, it’s slightly more verbose than just setting `cacheable: true`, which is working for now. ---
**Author:** ![bcoca](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/bcoca/32/9269_2.png) [@bcoca](https://forum.ansible.com/u/bcoca)\ **Post date:** [September 10, 2025, 2:29pm UTC](https://forum.ansible.com/t/how-to-retrieve-fact-with-a-dynamic-fact-name/44431/11 "2025-09-10T14:29:53Z")
fun note, this actually creates 2 copies of the variable, the normal `set_fact` creates a host scoped variable at higher precedence than facts, when you set `cacheable` you ALSO create a copy and insert it into `ansible_facts`. ---
**Author:** ![system](https://us1.discourse-cdn.com/ansible/original/1X/1882d9a01da5d8996a862359b0913cc568a39b84.svg) [@system](https://forum.ansible.com/u/system)\ **Post date:** [October 10, 2025, 2:30pm UTC](https://forum.ansible.com/t/how-to-retrieve-fact-with-a-dynamic-fact-name/44431/12 "2025-10-10T14:30:51Z")
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