nginx.conf.erb

daemon off;
#Heroku dynos have at least 4 cores.
worker_processes <%= ENV['NGINX_WORKERS'] || 4 %>;

events {
  use epoll;
  accept_mutex on;
  worker_connections <%= ENV['NGINX_WORKER_CONNECTIONS'] || 1024 %>;
}

http {
  gzip on;
  gzip_comp_level 2;
  gzip_min_length 512;
  gzip_proxied any; # Heroku router sends Via header

  server_tokens off;

  geoip2_proxy 10.0.0.0/8;
  geoip2 /app/GeoLite2-City.mmdb {
    $geoip2_city city names en;
    $geoip2_state subdivisions 0 iso_code;
  }
  geoip2 /app/GeoLite2-ASN.mmdb {
    $geoip2_asn autonomous_system_organization;
  }
  # A hack see: https://stackoverflow.com/questions/14433309/how-to-define-a-global-variable-in-nginx-conf-file
  map $geoip2_city $location {
    "" $geoip2_asn;
    default "$geoip2_city, $geoip2_state";
  }

  log_format l2met '[nginx] measure#nginx.service=$request_time request_id=$http_x_request_id' location=$location;
  access_log <%= ENV['NGINX_ACCESS_LOG_PATH'] || 'logs/nginx/access.log' %> l2met;
  error_log <%= ENV['NGINX_ERROR_LOG_PATH'] || 'logs/nginx/error.log' %>;

  include mime.types;
  default_type application/octet-stream;
  sendfile on;

  #Must read the body in 5 seconds.
  client_body_timeout 5;

  upstream app_server {
    server unix:/tmp/nginx.socket fail_timeout=0;
  }

  server {
    listen <%= ENV["PORT"] %>;
    server_name _;
    keepalive_timeout 5;

    location / {
      proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
      proxy_set_header Host $http_host;
      proxy_redirect off;
      proxy_pass http://app_server;
    }
  }
}