NGINX Tuning For Best Performance
=================================

For this configuration you can use web server you like, i decided, because i work mostly with it to use nginx.

Generally, properly configured nginx can handle up to 400K to 500K requests per second (clustered), most what i saw is 50K to 80K (non-clustered) requests per second and 30% CPU load, course, this was `2 x Intel Xeon` with HyperThreading enabled, but it can work without problem on slower machines.

__You must understand that this config is used in testing environment and not in production so you will need to find a way to implement most of those features best possible for your servers.__

* [Stable version NGINX (deb/rpm)](https://nginx.org/en/linux_packages.html#stable)
* [Mainline version NGINX (deb/rpm)](https://nginx.org/en/linux_packages.html#mainline)

First, you will need to install nginx

```bash
yum install nginx
apt install nginx
```

Backup your original configs and you can start reconfigure your configs. You will need to open your `nginx.conf` at `/etc/nginx/nginx.conf` with your favorite editor.

```nginx
# you must set worker processes based on your CPU cores, nginx does not benefit from setting more than that
worker_processes auto; #some last versions calculate it automatically

# number of file descriptors used for nginx
# the limit for the maximum FDs on the server is usually set by the OS.
# if you don't set FD's then OS settings will be used which is by default 2000
worker_rlimit_nofile 100000;

# only log critical errors
error_log /var/log/nginx/error.log crit;

# provides the configuration file context in which the directives that affect connection processing are specified.
events {
    # determines how much clients will be served per worker
    # max clients = worker_connections * worker_processes
    # max clients is also limited by the number of socket connections available on the system (~64k)
    worker_connections 4000;

    # optmized to serve many clients with each thread, essential for linux -- for testing environment
    use epoll;

    # accept as many connections as possible, may flood worker connections if set too low -- for testing environment
    multi_accept on;
}

# cache informations about FDs, frequently accessed files
# can boost performance, but you need to test those values
open_file_cache max=200000 inactive=20s; 
open_file_cache_valid 30s; 
open_file_cache_min_uses 2;
open_file_cache_errors on;

# to boost I/O on HDD we can disable access logs
access_log off;

# copies data between one FD and other from within the kernel
# faster then read() + write()
sendfile on;

# send headers in one peace, its better then sending them one by one 
tcp_nopush on;

# don't buffer data sent, good for small data bursts in real time
tcp_nodelay on;

# reduce the data that needs to be sent over network -- for testing environment
gzip on;
gzip_min_length 10240;
gzip_proxied expired no-cache no-store private auth;
gzip_types text/plain text/css text/xml text/javascript application/x-javascript application/json application/xml;
gzip_disable msie6;

# allow the server to close connection on non responding client, this will free up memory
reset_timedout_connection on;

# request timed out -- default 60
client_body_timeout 10;

# if client stop responding, free up memory -- default 60
send_timeout 2;

# server will close connection after this time -- default 75
keepalive_timeout 30;

# number of requests client can make over keep-alive -- for testing environment
keepalive_requests 100000;
```

Now you can save config and run bottom [command](https://www.nginx.com/resources/wiki/start/topics/tutorials/commandline/#stopping-or-restarting-nginx)

```
nginx -s reload
/etc/init.d/nginx start|restart
```

If you wish to test config first you can run

```
nginx -t
/etc/init.d/nginx configtest
```

Just For Security Reason
------------------------

```nginx
server_tokens off;
```

Nginx Simple DDoS Defense
-------------------------

This is far away from secure DDoS defense but can slow down some small DDoS. Those configs are also in test environment and you should do your values.

```nginx
# limit the number of connections per single IP
limit_conn_zone $binary_remote_addr zone=conn_limit_per_ip:10m;

# limit the number of requests for a given session
limit_req_zone $binary_remote_addr zone=req_limit_per_ip:10m rate=5r/s;

# zone which we want to limit by upper values, we want limit whole server
server {
    limit_conn conn_limit_per_ip 10;
    limit_req zone=req_limit_per_ip burst=10 nodelay;
}

# if the request body size is more than the buffer size, then the entire (or partial)
# request body is written into a temporary file
client_body_buffer_size  128k;

# headerbuffer size for the request header from client -- for testing environment
client_header_buffer_size 3m;

# maximum number and size of buffers for large headers to read from client request
large_client_header_buffers 4 256k;

# read timeout for the request body from client -- for testing environment
client_body_timeout   3m;

# how long to wait for the client to send a request header -- for testing environment
client_header_timeout 3m;
```

Now you can do again test config

```bash
nginx -t # /etc/init.d/nginx configtest
```
And then [reload or restart your nginx](https://www.nginx.com/resources/wiki/start/topics/tutorials/commandline/#stopping-or-restarting-nginx)

```
nginx -s reload
/etc/init.d/nginx reload|restart
```

You can test this configuration with `tsung` and when you are satisfied with result you can hit `Ctrl+C` because it can run for hours.

DoS [HTTP/1.1 and above: Range Requests](https://tools.ietf.org/html/rfc7233#section-6.1)
----------------------------------------

By default [`max_ranges`](https://nginx.org/r/max_ranges) is not limited.
DoS attacks can many Range-Requests (Impact on stability I/O).

Socket Sharding in NGINX 1.9.1+ (DragonFly BSD and Linux 3.9+)
-------------------------------------------------------------------

| Socket type      | Latency (ms) | Latency stdev (ms) | CPU Load |
|------------------|--------------|--------------------|----------|
| Default          | 15.65        | 26.59              | 0.3      |
| accept_mutex off | 15.59        | 26.48              | 10       |
| reuseport        | 12.35        | 3.15               | 0.3      |

[Thread Pools](https://nginx.org/r/thread_pool) in NGINX Boost Performance 9x! (Linux)
--------------

[Multi-threaded](https://nginx.org/r/aio) sending of files is currently supported only Linux.
Without [`sendfile_max_chunk`](https://nginx.org/r/sendfile_max_chunk) limit, one fast connection may seize the worker process entirely.

Happy Hacking!
--------------

* http://www.codestance.com/tutorials-archive/nginx-tuning-for-best-performance-255
* https://www.keycdn.com/support/tcp-fast-open/
* ~~https://www.52os.net/articles/nginx-anti-ddos-setting-2.html~~
* https://github.com/h5bp/server-configs-nginx
* https://github.com/nginx-boilerplate/nginx-boilerplate
* https://www.nginx.com/blog/thread-pools-boost-performance-9x/
* https://www.nginx.com/blog/socket-sharding-nginx-release-1-9-1/
* https://www.nginx.com/blog/performing-a-b-testing-nginx-plus/
* https://www.nginx.com/blog/10-tips-for-10x-application-performance/
* https://nginx.org/r/pcre_jit
* https://nginx.org/r/ssl_engine (`openssl engine -t `)
* https://www.nginx.com/blog/mitigating-ddos-attacks-with-nginx-and-nginx-plus/
* https://www.nginx.com/blog/tuning-nginx/
* https://www.maxcdn.com/blog/nginx-application-performance-optimization/
* https://www.linode.com/docs/websites/nginx/configure-nginx-for-optimized-performance