Are facts carried forward?

Archives Ansible Project
1

We have many playbooks, and groups.
I notice when I do a full site run that at the beginning of the ‘top level’ playbooks, that is those referenced by site.yml, that facts are gathered each time.
I realize I can disable gathering facts for a given playbook.
Are facts that are previously gathered carried forward, allowing us to gather just once for a run?

Thanks!
-Michael

2

Answered this exact same question here yesterday:

Facts are available throughout the playbook run, or longer, if fact caching is enabled.

http://docs.ansible.com/playbooks_variables.html#fact-caching

3

Fact-caching will eliminate the need for the following workaround, but if you are stuck in pre 1.8 ansible…

If you have a bunch of plays in a site.yml and are a big fan of --start-at-task like i am, then there is a problem if downstream plays also require gathered facts.Having gather_facts: yes for every play slows things down.

  • hosts: all
    gather_facts: yes

  • hosts: group1
    gather_facts: no # faster not to gather_facts if we got them above
    roles:

  • role-that-uses-facts

But then if you start-at-task on the group1 play you don’t have the facts you need.

My solution was to have the first role always gather facts for normal runs.

  • hosts: zoo
    gather_facts: “{{ zoo_facts | default(‘no’)}}”

Then when debugging/developing i run with
ansible-playbook -i hosts site.yml --start-at-task=“task in zoo role” -e “zoo_facts=yes”

So we can start mid run, and switch on gathering facts for that role, but normally only the first play will gather facts.

4

Are you aware of 'smart' fact gathering? I think this might ameliorate
your problems:

http://docs.ansible.com/intro_configuration.html#gathering

5

Smart fact gathering won’t rerun fact gathering on a host that has already gathered, but it will not gather hosts explicitly on hosts that have not been gathered.

So it’s basically a performance tweak.