Nginx Essentials: Excel in Nginx quickly by learning to use its most essential features in real-life applications

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Nginx Essentials

Chapter 2. Managing Nginx

In a web server running at full scale, thousands of events are occurring each second. Micromanaging these events is obviously not possible, yet even small glitches are able to cause serious deterioration of quality of service and affect user experience.

To prevent theses glitches from happening, a dedicated webmaster or site reliability engineer must be able to understand and properly manage the processes behind the scenes.

In this chapter, you will learn how to manage an Nginx instance in operation, and we will discuss the following topics:

Starting and stopping Nginx
Reloading and reconfiguring processes
Allocating worker processes
Other management questions

Control signals and their usage

Nginx, like any other Unix background service, is controlled by signals. Signals are asynchronous events that interrupt normal execution of a process and activate certain functions. The following table lists all signals that Nginx supports and the functions that they trigger:

Signal	Function
`TERM`, `INT`	Fast shutdown
`QUIT`	Graceful shutdown
`HUP`	Reconfiguration
`USR1`	Log file reopening
`USR2`	Nginx binary upgrade
`WINCH`	Graceful worker shutdown

All signals must be sent to the master process of an instance. The master process of an instance can be located by looking it up in the process list:

# ps -C nginx -f
UID        PID  PPID  C STIME TTY          TIME CMD
root      4754  3201  0 11:10 ?        00:00:00 nginx: master process /usr/sbin/nginx
www-data  4755  4754  0 11:10 ?        00:00:00 nginx: worker process
www-data  4756  4754  0 11:10 ?        00:00:00 nginx: worker process
www-data  4757  4754  0 11:10 ?        00:00:00 nginx: worker...

Distribution-specific startup scripts

On Ubuntu, Debian, and RHEL, the startup script automates the preceding control sequences. By using the startup script, you don't need to remember the exact sequence of the commands and signal names. The following table illustrates the use of the startup script:

Command	Equivalent to
`service nginx start`	`sbin`/`nginx`
`service nginx stop`	`TERM`, `wait 30 seconds`, then `KILL`
`service nginx restart`	`service nginx stop` and `service nginx start`
`service nginx configtest`	`nginx -t <config file>`
`service nginx reload`	`service nginx configtest` and `HUP`
`service nginx rotate`	`USR1`
`service nginx upgrade`	`USR2` and `QUIT to the old master`
`service nginx status`	`show status of the instance`

The binary upgrade procedure is limited to starting the new binary and signaling the old master process to gracefully shut down, so you don't have an option to test-drive the new binary in this case.

Control signals and their usage

Signal	Function
`TERM`, `INT`	Fast shutdown
`QUIT`	Graceful shutdown
`HUP`	Reconfiguration
`USR1`	Log file reopening
`USR2`	Nginx binary upgrade
`WINCH`	Graceful worker shutdown

All signals must be sent to the master process of an instance. The master process of an instance can be located by looking it up in the process list:

# ps -C nginx -f
UID        PID  PPID  C STIME TTY          TIME CMD
root      4754  3201  0 11:10 ?        00:00:00 nginx: master process /usr/sbin/nginx
www-data  4755  4754  0 11:10 ?        00:00:00 nginx: worker process
www-data  4756  4754  0 11:10 ?        00:00:00 nginx: worker process
www-data  4757  4754  0 11:10 ?        00:00:00 nginx: worker...

Distribution-specific startup scripts

Command	Equivalent to
`service nginx start`	`sbin`/`nginx`
`service nginx stop`	`TERM`, `wait 30 seconds`, then `KILL`
`service nginx restart`	`service nginx stop` and `service nginx start`
`service nginx configtest`	`nginx -t <config file>`
`service nginx reload`	`service nginx configtest` and `HUP`
`service nginx rotate`	`USR1`
`service nginx upgrade`	`USR2` and `QUIT to the old master`
`service nginx status`	`show status of the instance`

The binary upgrade procedure is limited to starting the new binary and signaling the old master process to gracefully shut down, so you don't have an option to test-drive the new binary in this case.

What you will learn

Get started with an Nginx installation from scratch in various environments and customize it for your purposes

Start and stop a basic Nginx installation, discover the basics of process management, and learn how to set up Nginx to serve static data

Create highlymaintainable configuration files to perform the most critical Nginx maintenance tasks

Set up Nginx as a reverse proxy and learn to use the Nginx caching feature

Discover how to benefit from the Nginx rewrite engine and how to use access restrictions in Nginx

Use various Nginx features to manage inbound traffic and understand how to use Nginx load balancing and fault tolerance features

Understand advanced featureindependent performance tuning strategies and optimizations

Manage inbound and outbound traffic and configure access control

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Nginx Essentials

Jul 2015 150 pages

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SilentG Sep 18, 2015

I read a large volume of technical books, articles, etc and finding a good useful technical book can be tricky.This book does a really nice job of covering useful ground with Nginx without wallowing in introductory information (what is the Internet, what is a web server).While this book is relatively short in length it doesn't waste time with junk information or convoluted examples that are difficult to follow.I definitely recommend this book if you are new to Nginx as it will help you to fill in some gaps as far as how Nginx does things and when finished you should be much more comfortable with Nginx.

Brian Nov 25, 2015

This book includes a very readable overview of how Nginx actually works. It was nice to understand it from a conceptual level, rather than just going through the motions and praying that a configuration will work. My only complaint is I would have enjoyed a little more 'meat' in the configuration chapter. Specifically more coverage on vhosts, setup for wordpress etc.

Giuseppe Rodriguez Oct 04, 2015

Ngnix Essentials is by far one of the most advanced and up to date books you can find out there that explains step by step the technicality of setting up an Nginx server.Whether you're a back-end developer looking into incorporating resource servers and load balancers to your current deployment stack, or you want to move on to a leaner server than Apache and experience feature such as1.Less RAM consumption.2. Better caching3. Fast web page delivery.Then this book is for you.Nginx Essentials seems very fast paced and hand on, however the author goes more in depth in the upcoming chapters and wraps up with an actual real life project. If you want to try out Nginx and want to know what all the fuss is about, I highly recommend this book.

1304 Feb 20, 2016

Buch ist wohl gedacht für Experten, die sehr viel Ahnung von Web Servern / Proxy Servern /Load Balancern haben, weil sie z.B. lange Zeit mit anderen Programmen gearbeitet haben, und nun einen schnellen Einstieg in NGINX suchen. Für diese ist das Buch geeignet - allerdings ist es in weiten Teilen nur eine Zusammenstellung der Online-Dokumentation. Wer under den Experten andere Darstellungsform als die Web Seite mag, findet hier wohl, was er sucht.Für diejenigen Anweder, welche nicht zu obiger Gruppe gehören, sind die Erklärungen viel zu dürftig. Meist sind es nur Beispiele, von denen der Leser dann die Erkenntnis selbst ableiten muss. Auch im Hinblick auf den Preis ist das Buch für diese Lesergruppe wohl enttäuschend.

Nginx Essentials: Excel in Nginx quickly by learning to use its most essential features in real-life applications

What do you get with Print?

Nginx Essentials

Chapter 2. Managing Nginx

The Nginx connection processing architecture

Starting and stopping Nginx

Control signals and their usage

Distribution-specific startup scripts

Allocating worker processes

The Nginx connection processing architecture

Starting and stopping Nginx

Control signals and their usage

Distribution-specific startup scripts

Allocating worker processes

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