Using role metadata allows us to specify that our role depends on other roles. For example, if the application you are deploying needs to send an e-mail, your role could depend on a Postfix role. This would mean that before the application is set up and installed, Postfix will be installed and set up.
meta/main.yml file will look similar to the following code:
--- allow_duplicates: no dependencies: - apache
allow_duplicates line is set to
no, which is the default. If you set this to
no, Ansible will not run a role the second time, if it is included twice with the same arguments. If you set it to
yes, it will repeat the role even if it has run before. You can leave it
off instead of setting it to
Dependencies are specified ...