playbook格式问题

---
- hosts: 120.55.89.170
  remote_user: root
  
  tasks:
  - name: copy file
    copy: src=/root/initial-setup-ks.cfg dest=/root/initial-setup-ks.cfg
我这样写是可以执行的， 但是这个hosts不就写死了吗？ 这里hosts后面应该怎么写？ 谢谢！！

---
- hosts: {{ 这里应该怎么写 }}
  remote_user: root
  
  tasks:
  - name: copy file
    copy: src=/root/initial-setup-ks.cfg dest=/root/initial-setup-ks.cfg