ansible变量

变量的加载优先级如下:    
    The order of precedence is:
        - play->roles->get_default_vars (if there is a play context)
        - group_vars_files[host] (if there is a host context)
        - host_vars_files[host] (if there is a host context)
        - host->get_vars (if there is a host context)
        - fact_cache[host] (if there is a host context)
        - play vars (if there is a play context)
        - play vars_files (if there‘s no host context, ignore
          file names that cannot be templated)
        - task->get_vars (if there is a task context)
        - vars_cache[host] (if there is a host context)
        - extra vars

STATIC_VARS = [
    ‘ansible_version‘,
    ‘ansible_play_hosts‘,
    ‘inventory_hostname‘,
    ‘inventory_hostname_short‘,
    ‘inventory_file‘,
    ‘inventory_dir‘,
    ‘groups‘,
    ‘group_names‘,
    ‘omit‘,
    ‘playbook_dir‘,
    ‘play_hosts‘,
    ‘role_names‘,
    ‘ungrouped‘,
]