NginX - good practices, tips and advanced techniques

NginX - Good practices, tips
and advanced techniques
Claudio Filho
<claudio.ﬁlho@locaweb.com.br>

About me
+14 years experience with Linux/Unix.
Technical Operations Leader at Locaweb.
I can handle myself in different languages such as
Python, Perl, PHP, Bash, Lua, C and I'm learning
Ruby.
USF4 Player (PSN ID: but3k4 or piupiu_monstro).

A brief description about NginX
NginX (pronounced "engine X”) is an
OpenSource HTTP and reverse proxy server,
a mail proxy server, and a load balancing
server.
Currently it is the second most popular web
server on the Internet.

Good Practices
NginX is ﬂexible, it allows to do the same thing
in different ways, but, good practices can save
resources and increase the performance
(such as good programming techniques).

try_files is basically a replacement for the typical mod_rewrite
style file/directory existence check.
If possible, avoid to use “if (-f …), it is a bad practice(according
to author of NginX)., ex:
bad:
if (-f $request_filename) {
…………….
}
good:
location / {
try_files $uri $uri/ = 404;
}
try_files instead of if

Using the return directive we can completely
avoid evaluation of regular expression.
bad:
rewrite ^/(.*)$ http://domain.com/$1 permanent;
also bad:
rewrite ^ http://domain.com$request_uri? permanent;
good:
return 301 http://domain.com$request_uri;
return instead of rewrite

Avoid proxy everything. The try_files directive tries files in a specific
order. This means that NginX can first look for a number of static
files to serve and if not found move on to a user defined fallback.
proxy everything
bad:
location / {
proxy_pass http://upstream_servers;
}
good:
location / {
try_files $uri $uri/ @proxy;
}
location @proxy {
proxy_pass http://upstream_servers;
}

You can include any configuration files for what ever
purpose you want. The include directive also supports
filename globbing. The examples below show how the
nginx.conf file already uses includes by default:
include files
include /etc/nginx/conf.d/*.conf;
or
include conf.d/*.conf;

Tips
NginX has dozen of modules (native or third-
party), each module has a lot of directive,
each directive has its own peculiarities.

core module
core module has a lot of directives, among of them, there are
interested directives:
http2
location
limit_rate
error_page
resolver
try_ﬁles

http rewrite module
This module makes it possible to change URI using Perl
Compatible Regular Expressions (PCRE), and to redirect and
select conﬁguration depending on variables. This cycle can be
repeated up to 10 times, after which Nginx returns a 500 error.
server_name ~^(?P<subdomain>[wd-]+.)?(?P<domain>[wd-]+).(?P<cctld>[w.]+)$;
set $docroot "default";
if ($domain) {
set $docroot $domain;
}
root /srv/$docroot/www;

gzip log files
If you want, you can specify compression of the log files. If the gzip
parameter is used, then the buffered data will be compressed before
writing to the file.
Since the data is compressed in atomic blocks, the log file can be
decompressed or read by "zcat" at any time.
format:
access_log location format gzip;
ex:
access_log /var/log/nginx/access.log.gz combined gzip;

http map module
The http map module enable to create variables whose values
depend on values of other variables. You can create new
variable whose value depends on values of one or more of the
source variables speciﬁed in the ﬁrst parameter.
map $http_user_agent $bad_user_agent {
default 0;
~*wget 1;
~*curl 1;
~*libwww-perl 1;
~*python-urllib 1;
~*PycURL 1;
}

http echo module
This module wraps lots of Nginx internal APIs for
streaming input and output, parallel/sequential
subrequests, timers and sleeping, as well as various
meta data accessing.
location /echo {
default_type text/html;
echo -n "<html>n<head><title>echo</title></head>n<body><h1>echo</h1></body>n</html>
n";
}

http lua module
This module embeds Lua, via the standard Lua 5.1
interpreter or LuaJIT 2.0/2.1, into Nginx and by leveraging
Nginx's subrequests, allows the integration of the powerful
Lua threads (Lua coroutines) into the Nginx event model.
location /lua {
default_type text/plain;
content_by_lua “nginx.say(‘hello, world!’)“;
}

http perl module
The ngx_http_perl_module module is used to
implement location and variable handlers in
Perl and insert Perl calls into SSI.

http Live Streaming (HLS) module
The ngx_http_hls_module module provides HTTP Live
Streaming (HLS) server-side support for MP4 and MOV media
files. Such files typically have the .mp4, .m4v, .m4a, .mov, or .qt
filename extensions. The module supports H.264 video codec,
AAC and MP3 audio codecs.
http://www.claudioborges.org/sf4.mp4.m3u8?offset=1.000&start=1.000&end=2.200
http://www.claudioborges.org/sf4.mp4.m3u8?len=8.000
http://www.claudioborges.org/sf4.mp4.ts?start=1.000&end=2.200

third-party modules
These modules are not ofﬁcially supported and may not
be compatible across versions of Nginx. If you check this
(http://wiki.nginx.org/3rdPartyModules) you can ﬁnd
interested things. Enjoy at your own risk.
To compile a third-party module, from the Nginx source
directory, type:
./configure --add-module=/path/to/module1/source
--add-module=/path/to/module2/source

Advanced techniques
NginX is a powerful web server with a lot of
features. But, it has a few limitations. For
example, it doesn’t have nested ifs, but, you
can use a different way to do that.

nested if statement - part 1
Like I said, NginX doesn't allow nested if
statements, for example, you can't do
something like:
if ($http_refer ~* “.*claudioborges.*" && $args ~* “execute”) {
rewrite ^/things$ /another_thing break;
}

nested if statement part - 2
But, you can do using a different way:
set $result "";
if ($http_refer ~* ".*claudioborges.*") {
set $result 1;
}
if ($args ~* "execute") {
set $result 2;
}
if ($result = 2) {
rewrite ^/things$ /another_thing break;
}

Dynamic virtual host
You can use dynamic virtual hosts in NginX. I mean, you can
create just one ﬁle for many websites. It works similar to Apache
mod_vhost_alias.
server {
listen 80;
server_name ~^(?P<subdomain>[wd-]+.)?(?P<domain>[wd-]+).(?P<cctld>[w.]+)$;
index index.html;
set $docroot “default";
if ($domain) {
set $docroot $domain;
}
root /srv/$docroot/www;
location / {
try_files $uri $uri/ =404;
}
access_log /var/log/nginx/$domain-access.log main;
error_log /var/log/nginx/error.log;
}

HTTP and HTTPS in the same
virtual host - part 1
Unlike Apache, NginX allows to use the same
virtual host for both HTTP and HTTPS. Its
conﬁguration is pretty easy and using it avoid
duplicate conﬁgurations.

HTTP and HTTPS in the same
virtual host - part 2
To do that, you need to merge the HTTP and HTTPS virtual host ﬁle
in a unique ﬁle. The only detail is: You need to omit the "SSL on"
option. This directive in modern versions is thus discouraged.
The example below shows an unique virtual host that handles both
HTTP and HTTPS requests:
server {
listen 80;
listen 443 ssl http2;
server_name www.example.com;
ssl_certificate www.example.com.crt;
ssl_certificate_key www.example.com.key;
...
}

References
http://nginx.org
http://wiki.nginx.org/Pitfalls
http://wiki.nginx.org/IfIsEvil
http://wiki.nginx.org/3rdPartyModules
http://w3techs.com/technologies/cross/
web_server/ranking

Thanks for you attention!
Any questions?
Claudio Filho
<claudio.ﬁlho@locaweb.com.br>
@but3k4
http://www.claudioborges.org
https://github.com/but3k4

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