Nginx - Tips and Tricks.

Nginx - Tips & Tricks
#rootconf
May 2012
@tuxtoti

/me

Builds scalable systems for ADIQUITY

Works with web servers/load balancers

Identify bottlenecks in the architecture.

Responsible for smooth serving of Mobile
Ads.

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.

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

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

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.

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.

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;
}
}

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

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

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.

Nginx - Directives
empty_gif - Serves a 1x1 transparent gif
from memory. #USE - for dropping beacons/
pixels

location = /beacon {
empty_gif;
}

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;
}

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;
}
}
}

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

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;
}

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;

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.

Nginx - Builtin Variables

$arg_PARAM - To read the value of a GET
request PARAM.

$http_HEADER - To read the value of any
request HEADER.

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)

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

Nginx - Woes

No dynamically loadable modules yet.

Sparse/Bad documentation. (though better
now)

Nginx - Awesomeness

Vibrant community.

Very helpful for novices.

Active IRC/Mailing list

Nginx - Tips and Tricks.

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