ansible 192.168.1.21-m setup  获取系统信息，类似于Saltstack的Grains
ansible all -m setup -a "filter=ansible_hostname"  过滤某一个值

在模板文件中这样引用Facts信息：
{{ ansible_devices.sda.model }}  ansible_devices下的sda字典下key为model的值
{{ ansible_hostname }}    ansible_hostname的值


---------------------------
自定义Facts

目标机器操作
mkdir -pv /etc/ansible/facts.d
cd /etc/ansible/facts.d
vim preferences.fact
[general]
max_memory_size=32
max_user_processes=3730
open_files=65535

执行 ansible 192.168.8.22 -m setup -a "filter=ansible_local"
.....
"ansible_facts": {
        "ansible_local": {
            "preferences": {
                "general": {
                    "max_memory_size": "32", 
                    "max_user_processes": "3730", 
                    "open_files": "65535"
                }
            }
        }
    },
........