How to install dependent role on specific host with ansible -

i have following role/meta/main.yml script:

--- dependencies:   - role: common   - role: nginx   - role: postgres   - role: my_db 

and need install my_db role on specific host, lets 1.2.3.4, example.

if want install 1 roll, should create playbook applies role host.

- hosts:     - 1.2.3.4   roles:     - my_db