Add a postgresql dependency, if the want a local db server.

library/roles/powerdns-admin/defaults/main.yml

@@ -10,6 +10,7 @@ pdns_admin_opts: ''
 pdns_admin_loglevel: 'WARN'
 pdns_admin_logdir: '/var/log/pdnsadmin'
 pdns_admin_logfile: '{{ pdns_admin_logdir }}/pdnsadmin.log'
+pdns_admin_local_pgsql: False
 
 pdns_admin_prereqs:
   - git

library/roles/powerdns-admin/meta/main.yml

@@ -1,4 +1,5 @@
 ---
 dependencies:
+  - { role: '../../library/roles/nginx', when: pdns_admin_local_pgsql | bool }
   - role: '../../library/roles/nginx'
   - role: '../../library/roles/node_js'