nginx config file for Heroku nginx buildpack

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 1024;
}

http {
        gzip on;
        gzip_comp_level 2;
        gzip_min_length 512;

	server_tokens off;

	log_format l2met 'measure#nginx.service=$request_time request_id=$http_x_request_id';
	access_log logs/nginx/access.log l2met;
	error_log 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;
 	}

	# Expires map
	map $sent_http_content_type $expires {
		default                    off;
		text/html                  epoch;
		text/css                   max;
                text/plain                 max;
		application/javascript     max;
		~image/                    max;
	}

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

		expires $expires;

		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;
		}
	}
}

puma.rb

threads_count = ENV.fetch("RAILS_MAX_THREADS") { 4 }
threads threads_count, threads_count
environment ENV.fetch("RAILS_ENV") { "development" }
workers ENV.fetch("WEB_CONCURRENCY") { 2 }

preload_app!
before_fork do
  ActiveRecord::Base.connection_pool.disconnect! if defined?(ActiveRecord)
end

on_worker_boot do
  ActiveRecord::Base.establish_connection if defined?(ActiveRecord)
  FileUtils.touch('/tmp/app-initialized')
end

bind "unix:///tmp/nginx.socket"

plugin :tmp_restart