NGINX Tuning for Best Performance

---
title: NGINX Tuning for Best Performance
author: Denis Denisov
date: November 20, 2018
source: https://github.com/denji/nginx-tuning
notoc: false
---

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;

    # optimized 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;
}

http {
    # 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 than read() + write()
    sendfile on;

    # send headers in one piece, it is better than 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_static on;
    gzip_min_length 10240;
    gzip_comp_level 1;
    gzip_vary on;
    gzip_disable msie6;
    gzip_proxied expired no-cache no-store private auth;
    gzip_types
        # text/html is always compressed by HttpGzipModule
        text/css
        text/javascript
        text/xml
        text/plain
        text/x-component
        application/javascript
        application/x-javascript
        application/json
        application/xml
        application/rss+xml
        application/atom+xml
        font/truetype
        font/opentype
        application/vnd.ms-fontobject
        image/svg+xml;

    # 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;

# buffer size for reading client request header -- 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.

Increase The Maximum Number Of Open Files (`nofile` limit) -- Linux
-----------------------------------------------

Two ways to raise the nofile/max open files/file descriptors/file handles limit for NGINX in RHEL/CentOS 7+.
With NGINX running, checking current limit on master process

    $ cat /proc/$(cat /var/run/nginx.pid)/limits | grep open.files
    Max open files            1024                 4096                 files

#### And worker processes

    ps --ppid $(cat /var/run/nginx.pid) -o %p|sed '1d'|xargs -I{} cat /proc/{}/limits|grep open.files

    Max open files            1024                 4096                 files
    Max open files            1024                 4096                 files

Trying with the `worker_rlimit_nofile` directive in `{,/usr/local}/etc/nginx/nginx.conf` fails as SELinux policy doesn't allow `setrlimit`. This is shown in `/var/log/nginx/error.log`

    015/07/24 12:46:40 [alert] 12066#0: setrlimit(RLIMIT_NOFILE, 2342) failed (13: Permission denied)

#### And in /var/log/audit/audit.log

    type=AVC msg=audit(1437731200.211:366): avc:  denied  { setrlimit } for  pid=12066 comm="nginx" scontext=system_u:system_r:httpd_t:s0 tcontext=system_u:system_r:httpd_t:s0 tclass=process

#### `nolimit` without Systemd

    $ nano /etc/security/limits.d/nginx.conf
    nginx   soft    nofile  65536
    nginx   hard    nofile  65536
    $ sysctl -p

#### `nolimit` with Systemd

    $ mkdir -p /etc/systemd/system/nginx.service.d
    $ nano /etc/security/limits.d/nginx.conf
    [Service]
    LimitNOFILE=30000
    $ systemctl daemon-reload
    $ systemctl restart nginx.service

#### SELinux boolean `httpd_setrlimit` to true(1)

This will set fd limits for the worker processes. Leave the `worker_rlimit_nofile` directive in `{,/usr/local}/etc/nginx/nginx.conf` and run the following as root

    setsebool -P httpd_setrlimit 1

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.

Selecting an upstream based on SSL protocol version
---------------------------------------------------
```nginx
map $ssl_preread_protocol $upstream {
    ""        ssh.example.com:22;
    "TLSv1.2" new.example.com:443;
    default   tls.example.com:443;
}

# ssh and https on the same port
server {
    listen      192.168.0.1:443;
    proxy_pass  $upstream;
    ssl_preread on;
}
```

Happy Hacking!
==============

Reference links
---------------

* http://www.codestance.com/tutorials-archive/nginx-tuning-for-best-performance-255
* https://www.keycdn.com/support/tcp-fast-open/
 * https://www.masv.io/enabling-tcp-fast-open-nginx-centos-7/
* ~~https://www.52os.net/articles/nginx-anti-ddos-setting-2.html~~
* https://ospi.fi/blog/centos-7-raise-nofile-limit-for-nginx.html
* https://www.nginx.com/blog/nginx-se-linux-changes-upgrading-rhel-6-6/
* 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/nginx-1-13-9-http2-server-push/
* https://www.nginx.com/blog/performing-a-b-testing-nginx-plus/
* https://www.nginx.com/blog/10-tips-for-10x-application-performance/
* https://www.nginx.com/blog/http-keepalives-and-web-performance/
* https://www.nginx.com/blog/overcoming-ephemeral-port-exhaustion-nginx-plus/
* https://www.nginx.com/blog/tcp-load-balancing-udp-load-balancing-nginx-tips-tricks/
* https://www.nginx.com/blog/introducing-cicd-with-nginx-and-nginx-plus/
* 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
* https://haydenjames.io/nginx-tuning-tips-tls-ssl-https-ttfb-latency/

Static analyzers
----------------
* https://github.com/yandex/gixy

Syntax highlighting
-------------------
* https://github.com/chr4/sslsecure.vim
* https://github.com/chr4/nginx.vim
* https://github.com/nginx/nginx/tree/master/contrib/vim

NGINX config formatter
----------------------
* https://github.com/1connect/nginx-config-formatter
* https://github.com/lovette/nginx-tools/tree/master/nginx-minify-conf

NGINX configuration tools
-------------------------
* https://github.com/nginxinc/crossplane
* https://github.com/valentinxxx/nginxconfig.io

BBR (Linux 4.9+)
----------------
* https://blog.cloudflare.com/http-2-prioritization-with-nginx/
* Linux v4.13+ as no longer required FQ (`q_disc`) with BBR.
* https://github.com/google/bbr/blob/master/Documentation/bbr-quick-start.md
* https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/commit/?id=218af599fa635b107cfe10acf3249c4dfe5e4123
* https://github.com/systemd/systemd/issues/9725#issuecomment-413369212
* If the latest Linux kernel distribution does not have `tcp_bbr` enabled by default:
```sh
modprobe tcp_bbr && echo 'tcp_bbr' >> /etc/modules-load.d/bbr.conf
echo 'net.ipv4.tcp_congestion_control=bbr' >> /etc/sysctl.d/99-bbr.conf
# Recommended for production, but with  Linux v4.13rc1+ can be used not only in FQ (`q_disc') in BBR mode.
echo 'net.core.default_qdisc=fq' >> /etc/sysctl.d/99-bbr.conf
sysctl --system
```