pillar

# /srv/pillar/nginx.sls

nginx:
  vhosts:
    foo:
      server_names:
        - example.com
        - www.example.com

sls

# /src/salt/nginx/vhosts.sls

{% for vhost, settings in pillar.get('nginx:vhosts', {}).items() %}
/etc/nginx/sites-available/{{vhost}}.conf:
  file.managed:
    - source: salt://nginx/files/vhost_template.conf
    - template: jinja
{% endfor %}

tests

$ salt-call pillar.items nginx
local:
  ----------
  foo:
    ----------
    server_names:
      - example.com
      - www.example.com

$ salt minion state.sls nginx.vhosts
minion:

Summary
-----------
Succeeded: 0
Failed:   0
-----------
Total:    0