# I don't understand gather\_subset **URL:** \ **Category:** Get Help\ **Created:** [June 19, 2024, 11:34am UTC](https://forum.ansible.com/t/i-dont-understand-gather-subset/6660 "2024-06-19T11:34:34Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![Norbert](https://avatars.discourse-cdn.com/v4/letter/n/f6c823/32.png) [@Norbert](https://forum.ansible.com/u/Norbert)\ **Post date:** [June 19, 2024, 11:34am UTC](https://forum.ansible.com/t/i-dont-understand-gather-subset/6660/1 "2024-06-19T11:34:34Z")
I want to get tailor-made ansible facts from some of my hosts and figured that i could use `ansible.builtin.setup` with `gather_subset` but the results are not as I thought. Consider the following test playbook which should produce nearly nothing: ```yaml - name: Fix Something hosts: mail become: true gather_facts: false tasks: - name: A become: true ansible.builtin.setup: gather_subset: - '!all' - '!min' - '!date_time' - name: B ansible.builtin.debug: msg: "{{ ansible_date_time }}" ``` It gets the whole `ansible_date_time` variable and I _ **wonder why** _. The result when I run this playbook is: ```auto ansible-playbook ./fix_pb.yml PLAY [Fix Something] ************************************************************************************************* TASK [A] ************************************************************************************************************* ok: [mail] TASK [B] ************************************************************************************************************* ok: [mail] => {} MSG: {'date': '2024-06-19', 'day': '19', 'epoch': '1718795981', 'epoch_int': '1718795981', 'hour': '11', 'iso8601': '2024-06-19T11:19:41Z', 'iso8601_basic': '20240619T111941008002', 'iso8601_basic_short': '20240619T111941', 'iso8601_micro': '2024-06-19T11:19:41.008002Z', 'minute': '19', 'month': '06', 'second': '41', 'time': '11:19:41', 'tz': 'UTC', 'tz_dst': 'UTC', 'tz_offset': '+0000', 'weekday': 'Wednesday', 'weekday_number': '3', 'weeknumber': '25', 'year': '2024'} PLAY RECAP *********************************************************************************************************** mail : ok=2 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0 ``` The last lines of the fact file show that ansible knows what I want: ```auto ... "gather_subset": [ "!all", "!min", "!date_time" ], ... ``` What is going on here ? Any pointers welcome ! Thanks you very much Norbert ---
**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:** [June 19, 2024, 6:52pm UTC](https://forum.ansible.com/t/i-dont-understand-gather-subset/6660/2 "2024-06-19T18:52:23Z")
I don’t understand it either, @Norbert . When I run the same code (against `localhost`), task “`B`” throws an undefined variable error. What does `ansible-config dump --only-changed` show? ---
**Author:** ![Denney-tech](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/denney-tech/32/1556_2.png) [@Denney-tech](https://forum.ansible.com/u/Denney-tech)\ **Post date:** [June 19, 2024, 7:04pm UTC](https://forum.ansible.com/t/i-dont-understand-gather-subset/6660/3 "2024-06-19T19:04:29Z")
> [@Norbert](#): > > The last lines of the fact file show that ansible knows what I want: The what now? Do you have fact caching enabled? If so, you may be seeing a previously cached date\_time fact. ---
**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:** [June 19, 2024, 7:08pm UTC](https://forum.ansible.com/t/i-dont-understand-gather-subset/6660/4 "2024-06-19T19:08:18Z")
That’s an excellent point/question. Does the time shown reflect the _current_ time, or the time of a prior run on that host? ---
**Author:** ![markuman](https://avatars.discourse-cdn.com/v4/letter/m/7bcc69/32.png) [@markuman](https://forum.ansible.com/u/markuman)\ **Post date:** [June 20, 2024, 11:44am UTC](https://forum.ansible.com/t/i-dont-understand-gather-subset/6660/5 "2024-06-20T11:44:12Z")
It’s because of `become: true` usage somehow. If everything is executed as default user (same context), I got > The error was: ‘ansible\_date\_time’ is undefined ```yml - name: Fix Something hosts: localhost gather_facts: false tasks: - name: A ansible.builtin.setup: gather_subset: - '!all' - '!min' - '!date_time' - name: B ansible.builtin.debug: msg: "{{ ansible_date_time }}" ``` Furthermore, `!all` excluded already everything. There is no need to exclude also `!date_time` and `!min`. ---
**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:** [June 20, 2024, 12:10pm UTC](https://forum.ansible.com/t/i-dont-understand-gather-subset/6660/6 "2024-06-20T12:10:31Z")
> [@markuman](#): > > Furthermore, `!all` excluded already everything. There is no need to exclude also `!date_time` and `!min`. You would think, but you’d be wrong. According to [ansible.builtin.setup module – Gathers facts about remote hosts — Ansible Community Documentation](https://docs.ansible.com/ansible/latest/collections/ansible/builtin/setup_module.html#parameter-gather_subset:) > If `!all` is specified then only the min subset is collected. To avoid collecting even the min subset, specify `!all,!min`. BTW, I used your code with `become: true`, so the blanket statement is not right. Evidently the cached facts you’re seeing are only readable by root. (?) Maybe that’s why you don’t see them w/o `become: true`. ---
**Author:** ![Norbert](https://avatars.discourse-cdn.com/v4/letter/n/f6c823/32.png) [@Norbert](https://forum.ansible.com/u/Norbert)\ **Post date:** [June 26, 2024, 11:45am UTC](https://forum.ansible.com/t/i-dont-understand-gather-subset/6660/7 "2024-06-26T11:45:42Z")
Interesting. Now (several days later) I see an undefined variable error. This here is my changed configuration(`ansible-config dump --only-changed`): ```auto CACHE_PLUGIN(/home/norbert/Sourcecode/Klamann_IT/branches/Neuaufbau/ansible/ansible.cfg) = jsonfile CACHE_PLUGIN_CONNECTION(/home/norbert/Sourcecode/Klamann_IT/branches/Neuaufbau/ansible/ansible.cfg) = facts CACHE_PLUGIN_PREFIX(/home/norbert/Sourcecode/Klamann_IT/branches/Neuaufbau/ansible/ansible.cfg) = ansible_facts. CONFIG_FILE() = /home/norbert/Sourcecode/Klamann_IT/branches/Neuaufbau/ansible/ansible.cfg DEFAULT_GATHERING(/home/norbert/Sourcecode/Klamann_IT/branches/Neuaufbau/ansible/ansible.cfg) = smart DEFAULT_HOST_LIST(/home/norbert/Sourcecode/Klamann_IT/branches/Neuaufbau/ansible/ansible.cfg) = ['/home/norbert/Sourc> DEFAULT_MANAGED_STR(/home/norbert/Sourcecode/Klamann_IT/branches/Neuaufbau/ansible/ansible.cfg) = Ansible managed: te> DEFAULT_PRIVATE_KEY_FILE(/home/norbert/Sourcecode/Klamann_IT/branches/Neuaufbau/ansible/ansible.cfg) = /home/norbert/> DEFAULT_REMOTE_USER(/home/norbert/Sourcecode/Klamann_IT/branches/Neuaufbau/ansible/ansible.cfg) = ansible DEFAULT_STDOUT_CALLBACK(/home/norbert/Sourcecode/Klamann_IT/branches/Neuaufbau/ansible/ansible.cfg) = debug DEFAULT_VAULT_PASSWORD_FILE(/home/norbert/Sourcecode/Klamann_IT/branches/Neuaufbau/ansible/ansible.cfg) = /home/norbe> RETRY_FILES_ENABLED(/home/norbert/Sourcecode/Klamann_IT/branches/Neuaufbau/ansible/ansible.cfg) = False ``` UPDATE 2 When I use `gather_facts=true` the `ansible_date_time` is filled. But I think it shouldn’t , because it is excluded. ---
**Author:** ![IPvSean](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/ipvsean/32/1153_2.png) [@IPvSean](https://forum.ansible.com/u/IPvSean)\ **Post date:** [June 26, 2024, 12:42pm UTC](https://forum.ansible.com/t/i-dont-understand-gather-subset/6660/8 "2024-06-26T12:42:46Z")
i have only used the `gather_subset` with the network automation modules, and they work fine, here is an example of how to use them: [toolkit/roles/facts/tasks/ios.yml at master · network-automation/toolkit · GitHub](https://github.com/network-automation/toolkit/blob/master/roles/facts/tasks/ios.yml) It is gathering or NOT gathering certain fact keys from network devices ---
**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:** [June 26, 2024, 12:54pm UTC](https://forum.ansible.com/t/i-dont-understand-gather-subset/6660/9 "2024-06-26T12:54:13Z")
Okay, let’s assume `gather_subset` is broken with respect to `ansible_date_time` in such a way that it gets set/updated when it shouldn’t be, and let’s also ignore whether that’s actually the case. (I still think it’s a fact caching issue, but, whatever.) Instead, let’s shift focus to what you want to accomplish, and how we can achieve that that in the face of strange `ansible_date_time` behavior. ---
**Author:** ![flowerysong](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/flowerysong/32/2305_2.png) [@flowerysong](https://forum.ansible.com/u/flowerysong)\ **Post date:** [June 26, 2024, 3:52pm UTC](https://forum.ansible.com/t/i-dont-understand-gather-subset/6660/10 "2024-06-26T15:52:13Z")
You have fact caching enabled, so it’s normal for facts gathered in previous runs to persist even if you don’t freshly gather those specific facts. > [@Norbert](#): > > When I use `gather_facts=true` the `ansible_date_time` is filled. But I think it shouldn’t , because it is excluded. The play keyword `gather_facts: true` adds another execution of the `setup` module that occurs before the rest of the play, and the arguments for your explicit call to the module are not relevant to how that execution behaves. You can use `module_defaults` to affect its execution, but because you have caching you’ll still have the issue where any other play that runs against this host can result in facts other than the ones you explicitly request in this play being available. ---
**Author:** ![Denney-tech](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/denney-tech/32/1556_2.png) [@Denney-tech](https://forum.ansible.com/u/Denney-tech)\ **Post date:** [June 26, 2024, 6:13pm UTC](https://forum.ansible.com/t/i-dont-understand-gather-subset/6660/11 "2024-06-26T18:13:42Z")
Since you are using fact caching, you will want to be aware that “gathered” facts are not necessarily updated when the fact is already cached. There is a configurable fact expiry period, but if you want to _make absolutely sure_ that a fact isn’t stale, you can use `meta: clear_facts` as a task to clean the cache (per host, not the entire cache). Because of this, `ansible_date_time` is not a particularly reliable fact whenever caching is enabled. What you may want to do instead, if you need the current date\_time, is to use the `{{ now() }}` [function](https://docs.ansible.com/ansible/latest/playbook_guide/playbooks_templating_now.html), which can be formatted with args. Otherwise, you’re fighting with your fact caching which is using the [default timeout](https://docs.ansible.com/ansible/latest/collections/ansible/builtin/jsonfile_cache.html) of 86400 seconds, or 24 hours. ---
**Author:** ![flowerysong](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/flowerysong/32/2305_2.png) [@flowerysong](https://forum.ansible.com/u/flowerysong)\ **Post date:** [June 26, 2024, 6:57pm UTC](https://forum.ansible.com/t/i-dont-understand-gather-subset/6660/12 "2024-06-26T18:57:44Z")
> [@Denney-tech](#): > > Since you are using fact caching, you will want to be aware that “gathered” facts are not necessarily updated when the fact is already cached. This is not correct (at least for the builtin plugins, and while it would theoretically be possible for other plugins to ignore updates it would break the API expectations and usually be a bad idea.) The cache affects whether facts that you have not gathered in the current run are available, and (in some configurations) whether play-level gathering happens. Gathered facts are always updated. ```yaml - hosts: localhost gather_facts: false tasks: - name: Uses the cached value because facts were not gathered debug: msg: "{{ ansible_facts.date_time.time }}" - gather_facts: - name: Has the freshly gathered value debug: msg: "{{ ansible_facts.date_time.time }}" - gather_facts: gather_subset: "!all,!date_time" - name: Still the fresher value debug: msg: "{{ ansible_facts.date_time.time }}" - gather_facts: gather_subset: date_time - name: Refreshed again debug: msg: "{{ ansible_facts.date_time.time }}" ``` ```yaml PLAY [localhost] *************************************************************** TASK [Uses the cached value because facts were not gathered] ******************* ok: [localhost] => msg: '14:51:14' TASK [gather_facts] ************************************************************ ok: [localhost] TASK [Has the freshly gathered value] ****************************************** ok: [localhost] => msg: '14:53:41' TASK [gather_facts] ************************************************************ ok: [localhost] TASK [Still the fresher value] ************************************************* ok: [localhost] => msg: '14:53:41' TASK [gather_facts] ************************************************************ ok: [localhost] TASK [Refreshed again] ********************************************************* ok: [localhost] => msg: '14:53:43' ``` ---
**Author:** ![Denney-tech](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/denney-tech/32/1556_2.png) [@Denney-tech](https://forum.ansible.com/u/Denney-tech)\ **Post date:** [June 26, 2024, 7:07pm UTC](https://forum.ansible.com/t/i-dont-understand-gather-subset/6660/13 "2024-06-26T19:07:46Z")
I stand corrected. I thought the point of cached facts wasn’t just to have it available for subsequent runs with `gather_facts: false`, but to improve the performance of `gather_facts` itself by skipping cached facts that are not expired. ---
**Author:** ![flowerysong](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/flowerysong/32/2305_2.png) [@flowerysong](https://forum.ansible.com/u/flowerysong)\ **Post date:** [June 26, 2024, 7:44pm UTC](https://forum.ansible.com/t/i-dont-understand-gather-subset/6660/14 "2024-06-26T19:44:32Z")
Well, that’s where we get into the question of configurations and what is meant by `gather_facts`. [`DEFAULT_GATHERING`](https://docs.ansible.com/ansible/latest/reference_appendices/config.html#default-gathering) has three possible values. ```yaml - name: Play with gather_facts=true hosts: localhost gather_facts: true tasks: - debug: msg: DEFAULT_GATHERING={{ lookup('config', 'DEFAULT_GATHERING') }} - name: Play without gather_facts hosts: localhost ``` With this playbook the default setting (`implicit`) gathers facts twice: ```plaintext PLAY [Play with gather_facts=true] ********************************************* TASK [Gathering Facts] ********************************************************* ok: [localhost] TASK [debug] ******************************************************************* ok: [localhost] => msg: DEFAULT_GATHERING=implicit PLAY [Play without gather_facts] *********************************************** TASK [Gathering Facts] ********************************************************* ok: [localhost] ``` `explicit` only gathers facts once: ```plaintext PLAY [Play with gather_facts=true] ********************************************* TASK [Gathering Facts] ********************************************************* ok: [localhost] TASK [debug] ******************************************************************* ok: [localhost] => msg: DEFAULT_GATHERING=explicit PLAY [Play without gather_facts] *********************************************** ``` and `smart` gathers facts zero times because of the cache: ```plaintext PLAY [Play with gather_facts=true] ********************************************* TASK [debug] ******************************************************************* ok: [localhost] => msg: DEFAULT_GATHERING=smart PLAY [Play without gather_facts] *********************************************** ``` However, this configuration (and the cache state) only matters for the play-level setting. The `gather_facts` task does not have the same logic, it’s just another task. ```plaintext PLAY [Play with gather_facts=true] ********************************************* TASK [debug] ******************************************************************* ok: [localhost] => msg: '15:37:17' TASK [gather_facts task] ******************************************************* ok: [localhost] TASK [debug] ******************************************************************* ok: [localhost] => msg: DEFAULT_GATHERING=smart TASK [debug] ******************************************************************* ok: [localhost] => msg: '15:38:07' ``` ---
**Author:** ![Norbert](https://avatars.discourse-cdn.com/v4/letter/n/f6c823/32.png) [@Norbert](https://forum.ansible.com/u/Norbert)\ **Post date:** [June 27, 2024, 6:09am UTC](https://forum.ansible.com/t/i-dont-understand-gather-subset/6660/15 "2024-06-27T06:09:39Z")
I marked one post as solution, but they all helped to get a better grip of the problem . Thanks to all ! ---
**Author:** ![system](https://us1.discourse-cdn.com/ansible/original/1X/1882d9a01da5d8996a862359b0913cc568a39b84.svg) [@system](https://forum.ansible.com/u/system)\ **Post date:** [July 27, 2024, 6:09am UTC](https://forum.ansible.com/t/i-dont-understand-gather-subset/6660/16 "2024-07-27T06:09:51Z")
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