Using facts from all systems

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1

As far as I understand it, fact variables are exposed for the current server that Ansible is operating on. So if I say: {{ ansible_default_ipv4.address }}, that is going to get evaluated for each host as I perform some operation using that variable.

I want that same variable, but for all hosts in the current play. Say I had three hosts I was operating against:

one: 98.0.0.1
two: 98.0.0.2
three: 98.0.0.3

I want to be able to do something like:

hosts={% for fact in facts %}
{{ fact[‘ansible_default_ipv4.address’] }},
{% endfor %}

and have that evaluated to “98.0.0.1,98.0.0.2,98.0.0.3”

2

hostvars['somehost']['ansible_default_ipv4'].address

inventory_hostname is a var worth mentioning: it's the hostname of the local system. useful for:
hostvars[inventory_hostname]['ansible_default_ipv4']

there's also a 'groups' top-level var you can use to iterate through the inventory, which may or may not be
better than iterating through hostvars to get your list of hosts. pardon, been a couple months since i touched
that particular use-case.

3

This is what I wanted: https://github.com/ansible/ansible/issues/196 So the resulting template code was:

hosts={% for k,v in hostvars.iteritems() %}{{v[‘ansible_default_ipv4’][‘address’]}},{% endfor %}

4

As far as I understand it, fact variables are exposed for the *current*
server that Ansible is operating on. So if I say: {{
ansible_default_ipv4.address }}, that is going to get evaluated for each
host as I perform some operation using that variable.

Not the case, actually.

Facts are available for all servers in the current play or talked to in any
previous play *OR* potentially all servers previously talked to if "fact
caching" is enabled.

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

Facts for other systems can be accessed like so using the "hostvars"
variable:

{{ hostvars["hostname.example.com"]["fact_name"] }}

For example:

{{ hostvars["hostname.example.com"]["ansible_default_ipv4"]["address"] }}

5

hostvars['somehost']['ansible_default_ipv4'].address

inventory_hostname is a var worth mentioning: it's the hostname of the
local system. useful for:
hostvars[inventory_hostname]['ansible_default_ipv4']

This can be simplified just down to:

{{ ansible_default_ipv4 }}

however.

It can be useful for when you need to fish out a variable name
programmatically though.

{{ hostvars[inventory_hostname]["some_variable"][name_of_hash_key] }}

etc