Nginx is a lightweight web server that was created in 2002 to address the C10K problem of scaling to 10,000 concurrent connections. It uses an asynchronous event-driven architecture that uses less memory and CPU than traditional multi-threaded models. Key features include acting as a reverse proxy, load balancer, HTTP cache, and web server. Nginx has grown in popularity due to its high performance, low memory usage, simple configuration, and rich feature set including modules for streaming, caching, and dynamic content.

1. Nginx - Tips & Tricks
#rootconf
May 2012
@tuxtoti

2. /me
Builds scalable systems for ADIQUITY
Works with web servers/load balancers
Identify bottlenecks in the architecture.
Responsible for smooth serving of Mobile
Ads.

3. Nginx - History
circa 2002. Igor Sysoev. Russian dev.
writes mod_accel. Realizes the Apache’s low
scalability.
2004 - powers rambler.ru. Initial public
version released.
was built to address the C10K problem
Now after ~10 yrs its Nginx Inc.

4. Nginx - C10K problem
To serve concurrent 10K connections
Why? I/O is the bottleneck. A thread per
connection model fails. #apachefail
select() vs epoll()
http://www.kegel.com/c10k.html

5. Nginx - Killer Features
L7 Load Balancer/Reverse proxy
Embedded perl interpreter
On the fly binary upgrade.
Awesome PCRE support. Useful for rewriting
URLs.
NGINX - Ultra-fast, Light weight, low
memory footprint, feature rich

6. Nginx - Config Contexts
http - The main scope . Typically configs set
here will reflect everywhere.
server - The to run multiple servers virtually
on different ports or with different server
names.
location - Defines the scope for a URI.
upstream - Config scope for a set of
upstream/backend servers.

7. Nginx - Directives
worker_processes, worker_connections,
worker_rlimit_nofile - Configure your setup
to the amount of traffic you expect to
receive.
Number of connections =
worker_processes*worker_connections
keepalive_requests, keepalive_timeout -
Configure based on your concurrency and
throughput.

8. Nginx - Directives
upstream - Set up a list of backends for load
balancing. W/ rr and wrr it becomes very
powerful. max_fails & fail_timeout - to
consider a backend inoperative.
upstream backend {
server 192.168.1.1;
server 192.168.1.5:8080;
server 192.168.1.13 weight=3;
server 192.168.1.16 max_fails=3 fail_timeout=10s;
keepalive 2048; #nginx > 1.1.4
}
server {
location / {
proxy_pass http://backend;
}
}

9. Nginx - Directives
rr vs fair - Send the request to the least
busy backend server. #Available as a third
party module
upstream backend {
fair;
server 192.168.1.2;
server 192.168.1.3;
}
fair - knows how many requests each
backend is processing.
no_rr

10. Nginx - Directives
proxy_next_upstream - To proceed or to not
proceed?
location ~ ^/(app) {
proxy_read_timeout 12;
proxy_set_header X-Feature-Foo “1”;
proxy_pass http://test_backend;
proxy_next_upstream error;
}
Takes values: error, timeout, invalid_header,
http_*, off

11. Nginx - Directives
add_header - Add custom headers to the
response. #USE - Debug to find out the
backend server / cache control headers.
add_header Cache-Control private;
proxy_set_header - Add custom headers to
control your backends. #USE - for enabling/
disabling features in your backend.

12. Nginx - Directives
empty_gif - Serves a 1x1 transparent gif
from memory. #USE - for dropping beacons/
pixels
location = /beacon {
empty_gif;
}

13. Nginx - Directives
limit_req_zone - Throttle the frequency of
requests for a client. #USE - mitigate DOS
attacks.
http {
limit_req_zone $binary_remote_addr
zone=one:10m rate=1r/s;
...
server {
...
location /search/ {
limit_req zone=one burst=4;
}

14. Nginx - Directives
limit_conn_zone - Throttle concurrency of
connections for a client.
http {
limit_conn_zone $binary_remote_addr
zone=one:2m;
server {
location /download {
limit_conn one 1;
}
}
}

15. Nginx - Directives
stub_status - To get the current status of
nginx. #USE - gives you info like the curr.
active conn., total conn. accepted and
handled, current no. of read/write/wait conn.
location /ngx_stat {
stub_status on;
access_log off;
}
Active connections: 291
server accepts handled requests
16630948 16630948 31070465
Reading: 6 Writing: 179 Waiting: 106

16. Nginx - Directives
map - To map a set of values to a different
set of values. #USE - for dynamically
changing hosts based on URIs.
map $uri $new {
default http://www.domain.com/home/;
/aa http://aa.domain.com/;
/bb http://bb.domain.com/;
/john http://my.domain.com/users/john/;
}
server {
server_name www.domain.com;
rewrite ^$new redirect;
}

17. Nginx - Directives
split_clients - To split clients based on some
conditions. #USE - for A/B testing in
variation in colors/designs.
http {
split_clients "${remote_addr}" $variant {
0.5% .one;
2.0% .two;
- "";
}
server {
location / {
index index${variant}.html;

18. Nginx - Directives
sub_filter - Search and replace content in
the response. #USE - Quick fix for stale
data/ typos?
error_pages - Custom error pages for your
#failwhale moments.
if/set/rewrite - powerful constructs for
condition based execution.

19. Nginx - Builtin Variables
$arg_PARAM - To read the value of a GET
request PARAM.
$http_HEADER - To read the value of any
request HEADER.

20. Nginx - Builtin Variables
$request_time - Measure end to end time.
#caveat - only from read() to write()/
sendfile()
$upstream_response_time - Measure end to
end time of your upstream server (w/
$upstream_addr)

21. Nginx - Modules
Embedded Perl - To execute perl directly
inside nginx.
XSLT - Transform your XML responses to
HTML in nginx.
FLV/MP4 - To stream FLV/MP4 content.
Addition - To add content of other locations
to the current location.
GeoIP/Mail/Image Filter/Memcached modules

22. Nginx - Woes
No dynamically loadable modules yet.
Sparse/Bad documentation. (though better
now)

23. Nginx - Awesomeness
Vibrant community.
Very helpful for novices.
Active IRC/Mailing list

24. Q?
Thanks !
@tuxtoti