gistfile1.txt

Pillar:

upstreams: ['127.0.0.1:8008','127.0.0.2:8008','127.0.0.3:8008']

sls:

    - context:
{% if pillar['upstreams'] is defined %}
      backends: "{{ pillar['upstreams'] }}"
{% endif %}

template:

{% for server in backends %}    server {{server}};
{% endfor %}}

produces:

upstream couponcabin {
	server 1;
	server 2;
	server 7;
	server .;
	server 0;
...
}

while template:

{% for server in [backends] %}  server {{server}};
{% endfor %}}

produces:

	server ['127.0.0.1:8008', '127.0.0.2:8008', '127.0.0.3:8008'];