Ansible template usage and with_nested

Ansible - use of template and with_nested

#roles/myapp/tasks/main.yml
---
  - name: manage config files
    template: src={{ item[0].src }} dest=/etc/{{ item[1] }}/{{ item[0].dest }}
    with_nested:
      - config_files
      - app_instance

template

#roles/myapp/templates/conf1.j2
app_instance_name: {{ item.1 }}
port: {{ app_instance[item.1].port }}
option1: {{ app_instance[item.1].option1 }}

{% if item.1 == 'instance1' %}
do stuff
{% endif %}

{% if item.1 == 'instance2' %}
do other stuff
{% endif %}

vars

#roles/myapp/vars/main.yml
---
config_files:
  - { src: 'conf1.j2', dest: 'conf1.conf' }
  - { src: 'conf2.j2', dest: 'conf2.conf' }
app_instance:
  instance1:
    port: 888
    domain: example.com
    option1: "off"
  instance2:
    port: 889
    domain: example.org
    option1: "on"
# or should it be done this way:
# - name: instance3
#   domain: example.org
#   option1: "on"

I have a working role of this type, but not able to open source it. I've posted this here in hopes of getting feedback on my structuring of the variable and template play.