- {role: start-tomcat, tags: ['install']}}

ansible-playbook -i hosts <your yaml> --tags "install" -vvv

- hosts: <A> 
   environment: "{{your env}}" 
   pre_tasks: 
      - debug: msg = "Started deployment. 
      Current time is {{ansible_date_time.date}} {{ansible_date_time.time}} " 

   roles: 
      - {role: <your role>, tags: ['<respective tag>']} 
   post_tasks: 
      - debug: msg = "Completed deployment. 
      Current time is {{ansible_date_time.date}} {{ansible_date_time.time}}" 

- hosts: <B> 
   pre_tasks: 
      - debug: msg = "started.... 
      Current time is {{ansible_date_time.date}} {{ansible_date_time.time}} " 

   roles: 
      - {role: <your role>, tags: ['<respective tag>']} 
   post_tasks: 
      - debug: msg = "Completed the task.. 
      Current time is {{ansible_date_time.date}} {{ansible_date_time.time}}"

# file: user.yml  (playbook) 
--- 
- hosts: '{{ target }}' 
   user: ... 
playbook contd….

ansible-playbook user.yml --extra-vars "target = "<your host variable>"

$ ansible-playbook user.yml --extra-vars "target = <your hosts variable>" --listhosts