如何在Ansible中将主机指定为变量？配置后执行报错求助

网上找了不少相关示例，但都解决不了我的问题，具体情况如下：

情况1：通过变量指定目标主机 #

我的 test.yaml 内容如下：

---
- hosts: "{{ non_default_host }}"
  tasks:
    - debug:
        msg: 'This is the host specified'

执行以下命令：

ansible-playbook -i hosts test.yaml -e "non_default_host=<somehost>"

结果弹出一堆警告，playbook 直接跳过执行：

[WARNING]: No inventory was parsed, only implicit localhost is available
[WARNING]: provided host list is empty, only localhost is available
[WARNING]: Could not match supplied host pattern, ignoring somehost

PLAY [somehost]
skipping: no hosts matched

情况2：将主机改为 all #

把 test.yaml 里的 hosts 改成 all：

---
- hosts: all
  tasks:
    - debug:
        msg: 'This is the host specified'

再执行这条命令就能正常运行：

ansible-playbook -i 'somehost,'  test.yaml

内容的提问来源于stack exchange，提问作者user_dev