Salt stack, context and Jinja template

init.yml

#
# Some state file...
#
{% for site, args in pillar.get('sites', {}).items() %}
/etc/nginx/sites-available/{{ site }}: 
    file.managed:
        - source: salt://nginx/files/site.conf.jinja
        - template: jinja
        - context:
            site: {{ site }}
            args: {{ args }}
        - watch_in:
            - service: nginx
        - require:
            - pkg: nginx

{% if 'enable' in args and args.enable == True %}
/etc/nginx/sites-enabled/{{ site }}: 
    file.symlink:
        - target: /etc/nginx/sites-available/{{ site }}
        - require:
            - pkg: nginx
{% else %}
/etc/nginx/sites-enabled/{{ site }}: 
    file.absent:
        - require:
            - pkg: nginx
{% endif %}
{% endfor %}

site.conf.jinja

#
# The called Jinja template file
#
# file:  nginx/files/site.conf.jinja
#
{# Some NGINX config... #}


{% if 'magento' in args and args.magento == True -%}
# Something happens only if args has a member 'magento' and its value is 

# THE QUESTION: Is True here is BOOLEAN, or string, How can we check?

{% endif %}

sites.yml

#
# The "sites" pillar
#
# file:  pillar/sites/init.sls
#
sites:                                                                                                                                                       
  piwik:
    name: stats.webplatform.org
    default: True
    enable: True
    php: True
    wordpress: False
    http_server: nginx