upstream lms-preview-backend {
    {% for host in nginx_lms_preview_gunicorn_hosts %}
        server {{ host }}:{{ edxapp_lms_preview_gunicorn_port }} fail_timeout=0;
    {% endfor %}
}

server {
  # LMS-preview configuration file for nginx, templated by ansible

  listen {{ EDXAPP_LMS_PREVIEW_NGINX_PORT }};

  server_name preview.*;

  # CS184 requires uploads of up to 4MB for submitting screenshots.
  # CMS requires larger value for course assest, values provided
  # via hiera.
  client_max_body_size 4M;
  # request the browser to use SSL for all connections
  add_header Strict-Transport-Security "max-age=31536000; includeSubDomains";

  rewrite ^(.*)/favicon.ico$ /static/images/favicon.ico last;

  {% include "python_lib.zip.j2" %}
  {% include "common-settings.j2" %}

  location @proxy_to_lms-preview_app {
    {% if NGINX_SET_X_FORWARDED_HEADERS %}
    proxy_set_header X-Forwarded-Proto $scheme;
    proxy_set_header X-Forwarded-Port $server_port;
    proxy_set_header X-Forwarded-For $remote_addr;
    {% else %}
    proxy_set_header X-Forwarded-Proto $http_x_forwarded_proto;
    proxy_set_header X-Forwarded-Port $http_x_forwarded_port;
    proxy_set_header X-Forwarded-For $http_x_forwarded_for;
    {% endif %}

    # newrelic-specific header records the time when nginx handles a request.
    proxy_set_header X-Queue-Start "t=${msec}";

    proxy_set_header Host $http_host;

    proxy_redirect off;
    proxy_pass http://lms-preview-backend;
  }

  location / {
    {% if EDXAPP_LMS_PREVIEW_ENABLE_BASIC_AUTH|bool %}
      {% include "basic-auth.j2" %}
    {% endif %}
    try_files $uri @proxy_to_lms-preview_app;
  }

  # No basic auth security on the github_service_hook url, so that github can use it for cms
  location /github_service_hook {
    try_files $uri @proxy_to_lms-preview_app;
  }

  # No basic auth security on the heartbeat url, so that ELB can use it
  location /heartbeat {
    try_files $uri @proxy_to_lms-preview_app;
  }

  {% include "robots.j2" %}

  # Check security on this
  location ~ ^/static/(?P<file>.*) {
    root {{ edxapp_data_dir}};
    try_files /staticfiles/$file /course_static/$file =404;

    # return a 403 for static files that shouldn't be
    # in the staticfiles directory
    location ~ ^/static/(?:.*)(?:\.xml|\.json|README.TXT) {
        return 403;
    }
    # Set django-pipelined files to maximum cache time
    location ~ "/static/(?P<collected>.*\.[0-9a-f]{12}\..*)" {
        expires max;
        # Without this try_files, files that have been run through
        # django-pipeline return 404s
        try_files /staticfiles/$collected /course_static/$collected =404;
    }

    # Expire other static files immediately (there should be very few / none of these)
    expires epoch;
  }

  # Nginx does not support nested condition or or conditions so
  # there is an unfortunate mix of conditonals here.
  {% if NGINX_REDIRECT_TO_HTTPS %}
     {% if NGINX_HTTPS_REDIRECT_STRATEGY == "scheme" %}
  # Redirect http to https over single instance
  if ($scheme != "https") 
  { 
   set $do_redirect_to_https "true";
  }

     {% elif NGINX_HTTPS_REDIRECT_STRATEGY == "forward_for_proto" %}

  # Forward to HTTPS if we're an HTTP request... and the server is behind ELB 
  if ($http_x_forwarded_proto = "http") 
  {
   set $do_redirect_to_https "true";
  }
  {% endif %}

  # Execute the actual redirect
  if ($do_redirect_to_https = "true")
  {
  return 301 https://$host$request_uri;
  }
  {% endif %}

}
