All about nginx ...

1. Dhruba Mandal 1
Dhruba Mandal
Email : dhruvmandal@gmail.com

2. What is Nginx
NGINX is pronounced as "engine-ex" is an open-source, fast, lightweight and high-
performance web server that can be used to serve static files.
In its initial release, NGINX functioned for HTTP web serving. however Today, it also serves
as a reverse proxy server for HTTP, HTTPS, SMTP, IMAP, POP3 protocols, on the other hand,
it is also used for HTTP load balancer, HTTP cache, and email proxy for IMAP, POP3, and
SMTP.
NGINX improves content and application delivery, improves security, and facilitates
scalability and availability for the busiest websites on the internet.
It has attempt to answer the C10k problem. Where C10k is the challenge of managing (i.e.
10,000 connections at the same time.)
Some high profile companies using Nginx include IBM, Google, Atlassian, Autodesk, GitLab,
DuckDuckGo, T-Mobile, Microsoft, Adobe, Salesforce, VMware, LinkedIn, Cisco, Twitter,
Apple, Intel, Face book, and many more.
Dhruba Mandal 2

3. Why Nginx
 Nginx Uses single thread and is very fast Moreover it also Provides high level of
concurrency
 Nginx is Lightweight with small memory footprint (i.e. very small memory)
 NGINX provides various services such as reverse proxy, load balancer, and rate limit
network services
(Note : rate limiting is used to control the rate of traffic sent or received by a network
interface controller and is used to prevent DoS attacks.)
Reverse proxying is useful if we have multiple web services listening on various ports and
we need a single public endpoint to reroute requests internally
(i.e. It would allow us to host multiple domain names on port 80 while using a
combination of different NodeJs, Go and java to power separate web services behind the
scenes.)
Nginx can handle the logging, blacklisting, load balancing and serving static files while
the web services focus on what they need to do
Dhruba Mandal 3

4. Nginx Architecture
NGINX follows the master-slave architecture by supporting event-driven, asynchronous
and non-blocking mode
NGINX architecture is sliced into three different parts. They are
1. master
2. Workers
3. Cache (cache loader & cache manager )Dhruba Mandal
Note : An event-driven means it will respond to actions generated by the user or the
system.
Asynchronous systems do not depend on strict arrival times of signals or messages for
reliable operation
“Non blocking" means the function will never wait for something to happen.
4

5. 1. Master : Master is responsible for reading and validating configuration
( i.e. it is responsible for creating , binding and processing socket and also responsible
for starting terminating and maintaining the configured number of worker process )
It allocate the jobs for the workers as per the request from the client. Once the job
allocated to the workers, the master will look for the next request from the client that’s
it won’t wait for the response from the workers. Once the response comes from workers
master will send the response to the client.
Beside above it also controls nonstop binary updates , reopening of locked files and
also compiles embedded Perl script
2. Workers : Workers are the slaves in the NGINX architecture, will heed to the Master.
Each worker can handle more than 1000 request at a time in a single-threaded manner.
Once the process gets done, the response will be sent to the master.
The single-threaded will saves the RAM and ROM size by working on the same memory
space instead of different memory spaces.
The multi-threaded will work on different memory spaces.
Dhruba Mandal 5

6. Dhruba Mandal
3. Cache : Nginx cache is used to render the page very fast by getting from cache
memory instead of getting from the server. The pages are getting stored in cache
memory on the first request for the page.
There are two main component of Nginx cache
1. The cache loader
2. The cache manager
The cache Loader :. It loads metadata about previously cached data into the shared
memory zone . Loading the whole cache at once could consume sufficient resources to
slow NGINX performance during the first few minutes after startup.
To avoid this, configure iterative loading of the cache by including the following parameters
to the proxy_cache_path directive:
• loader_threshold – Duration of an iteration, in milliseconds (by default, 200)
• loader_files – Maximum number of items loaded during one iteration (by default, 100)
• loader_sleeps – Delay between iterations, in milliseconds (by default, 50)
The cache manager The cache manager is activated periodically to check the state of the
cache. If the cache size exceeds the limit set by the max_size parameter to the
proxy_cache_path directive, the cache manager removes the data that was accessed least
recently..
6

7. Features of Nginx
Dhruba Mandal
Easy Installation and maintenance
Improves Performance
Reduce the waiting time for users
Load Balancing
Provides HTTP server capabilities
Designed for maximum performance and stability
Functions for the proxy server
Reverse proxy with caching
FastCGI support with caching
URL rewriting and redirection
Handling of static files, index files, and auto-indexing
On the fly upgrades (Means can be upgraded without taking any down time )
7

8. Understanding Nginx Configuration
Dhruba Mandal
The core setting of Nginx are mainly configured in nginx.cong . These
configuration files are mainly structured into context
The Main context are
1. The Event Context &
2. The Http Context
Each and every context can have nested context that inherit every thing from their
parents but can also override the setting as needed .
Beside above context there are some important some important parameter in
files are
1. worker _processes
2. worker _connections
3. access.log & error.log &
4. gzip
8

9. Dhruba Mandal
1. The event Context : The “events” context is contained within the “main” context. It is
used to set global options that affect how Nginx handles connections at a general level.
There can only be a single events context defined within the Nginx configuration.
This context will look like this in the configuration file, outside of any other bracketed
contexts:
# main context
events {
# events context
. . .
}
Nginx uses an event-based connection processing model, so the directives defined within
this context determine how worker processes should handle connections.
Mainly, directives found here are used to either select the connection processing
technique to use, or to modify the way these methods are implemented.
9

10. Dhruba Mandal
2. The HTTP Context : When configuring Nginx as a web server or reverse proxy, the
“http” context will hold the majority of the configuration. This context will contain all
of the directives and other contexts necessary to define how the program will handle
HTTP or HTTPS connections.
The http context is a sibling of the events context, so they should be listed side-by-side,
rather than nested. They both are children of the main context:
# main context
events {
# events context
. . .
}
http {
# http context
. . .
}
10

11. Dhruba Mandal
2a. The Server Context : The “server” context is declared within the “http” context.
nested, It is nested bracketed context that allows for multiple declarations
The general format for server context may look something like
# main context
http {
# http context
server {
# first server context
}
server {
# second server context
}
}
The reason for allowing multiple declarations of the server context is that each instance
defines a specific virtual server to handle client requests.
You can have as many server blocks as you need, each of which can handle a specific
subset of connections.
11

12. Dhruba Mandal
2b. Location contexts : Location contexts share many relational qualities with server
contexts. As server context multiple location contexts can be defined, each location is
used to handle a certain type of client request, and each location is selected by virtue of
matching the location definition against the client request through a selection algorithm.
The general syntax looks like this:
location match_modifier location_match {
. . .
}
Location blocks live within server blocks (or other location blocks) and are used to
decide how to process the request URI (the part of the request that comes after the
domain name or IP address/port).
Beside above context other optional context are like : upstream context ,
split_clients context , map context , geo context , types context , charset_map etc.
12

13. Dhruba Mandal
3. worker _processes : worker process is the setting that find the number of Nginx
worker process (the default is 1)
In most of cases , running one work processes per CPU core work well . How ever
recommended setting is auto
4. Worker _connections : Worker connection is maximum number of connections
that each worker _processes can handle simultaneously .
By default it is 512 , but many system have enough resources to support large
number (i.e. 1024 , 2048 per work processes or even more )
5. access.log & error.log : This is used to log any error in Nginx and is also used for
debugging purpose
6 . gzip : These are the setting for gzip compression on Nginx response
13

14. Difference B/W Apache and Nginx
Dhruba Mandal
Apache Nginx
Apache is designed to be a web server Nginx is both a web server and a proxy server.
A single thread can only process one connection A single thread can handle multiple connections.
Apache follows multi-threaded approach to process
client requests
Nginx uses an event-driven approach to serve client
requests.
It handles dynamic content within the web server
itself.
It cannot process dynamic content natively
It cannot process multiple requests concurrently
with heavy web traffic.
It can process multiple client requests concurrently
and efficiently with limited hardware resources
Modules are dynamically loaded or unloaded
making it more flexible.
The modules cannot be loaded dynamically. They
must be compiled within the core software itself
Apache runs on all Unix like systems such as Linux,
BSD, etc. as well as completely supports Windows.
Nginx runs on modern Unix like systems; however it
has limited support for Windows.
14

15. Installing NGINX on Redhat/CentOS
Dhruba Mandal
Step 1: Use the following command to install the Epel repository.
sudo yum install epel-release
Step 2: Use the following command to update the repository
sudo yum update
Step 3: Install Nginx using the following command:
yum install nginx
Step 4 : Nginx does not start on its own. To get Nginx running, type:
sudo systemctl start nginx
If you are running a firewall, run the following commands to allow HTTP and HTTPS
traffic:
sudo firewall-cmd --permanent --zone=public --add-service=http
sudo firewall-cmd --permanent --zone=public --add-service=https
sudo firewall-cmd --reload
Enable Nginx to start when your system boots with below command
sudo systemctl enable nginx
15

16. Directories & files in Nginx
Dhruba Mandal
/etc/nginx/ : This directory contains default configuration root for Nginx Server
configuration files with in this instruct nginx how to behave
/etc/nginx/nginx.conf : This is the main configuration file of Nginx here global setting
like worker process , tuning , logging ,loading dynamic modules and references to
other Nginx configuration files are defined.
/etc/nginx/conf.d/ : This directory contains default HTTP server configuration files .
files in this directory ending in .conf are included in the top-level http block with in
/etc/nginx/nginx.conf
In some package repositories, this folder is named sites-enabled, and configuration
files are linked from a folder named site-available
/var/log/nginx/ : The /var/log/nginx/ directory is default log location for Nginx ,
access.log and error.log are found here which is used for debug information if the debug
module is enabled
16

17. Some Nginx Commands
Dhruba Mandal
Command Description
nginx -h Shows the NGINX help menu.
nginx -v Shows the NGINX version.
nginx -V Shows the NGINX version, build information, and configuration arguments
nginx -t Tests the NGINX configuration.
nginx -T
Tests the NGINX configuration and prints the validated configuration to the
screen
nginx -s signal
The -s flag sends a signal to the NGINX master process. You can send signals
such as stop , quit, reload and reopen
systemctl start nginx Start the nginx process , can also use systemctl restart nginx
systemctl stop nginx Stop nginx Process
systemctl status nginx Show the nginx status either running or failed
17

18. Serving Static Content in Nginx
Dhruba Mandal
For serving static content Overwrite the default HTTP server configuration located in
/etc/ nginx/conf.d/default.conf with the following NGINX configuration
example:
server {
listen 80 default_server;
server_name www.example.com;
location / {
root /usr/share/nginx/html;
# alias /usr/share/nginx/html;
index index.html index.htm;
}
}
Note : in some cases conf.d directory is not present , in that case create the directory
and change the path in /etc/nginx/nginx.conf . As here my static content is in
/usr/share/nginx/modules/* .conf I will change path to /etc/nginx/confd/* .conf
18

19. HTTP Load Balancing in Nginx
Dhruba Mandal
We can use Nginx as a load balancer in front of your web application.
Scenario : In our case we will be using load balancer on 2 tomcat with 1 Nginx .
Here we have 2 server both on centos 7 Linux
1. 10.0.205.53 ( Nginx + Tomcat1)
2. 10.0.205.50 ( Tomcat 2 )
19

20. Types of load balancing in Nginx
Dhruba Mandal
Nginx supports the following three types of load balancing:
1. Round Robin
2. Least – Connected
3. IP – hash
1. Round-robin – This is the default type for Nginx, which uses the typical round-robin
algorithm to decide where to send the incoming request . (i.e request will go one by one
on every server)
2. least-connected – As the name suggests, the incoming request will be sent to the
server that has the less number of connection.
3. ip-hash – This is helpful when you want to have persistence or stick connection of the
incoming request. In this type, the client’s ip-address is used to decide which server the
request should be sent to.
20

21. Dhruba Mandal
First we have to define the First, upstream:
Specify a unique name (may be name of your application) and list all the servers that
will be load-balanced by this Nginx. In my case I have named it proxy1
upstream proxy1
Here inside /etc/nginx/conf.d I have made file by name loadbalancer.conf in which I have
defined my both server . (file name can be any thing but should have .conf )
1. Round – robin method : – This is the default type for Nginx, which uses the
typical round-robin algorithm to decide where to send the incoming request . (i.e
request will go one by one on every server)
21

22. Dhruba Mandal
Second, proxy_pass: Specify the unique upstream name that was defined in the
previous step as proxy_pass inside your “location” section, which will be under
“server” section as shown below.
You can define in same file or can make another config file I have made default.conf
In proxypass I have given the complete location of my URL with path
http://10.0.205.53/ideavodapanel if I give only 10.0.205.53 in my browser it will take
whole path 22

23. Dhruba Mandal
Instead of 2 files you can also define it in one file
vim /etc/nginx/conf.d/default.conf
upstream proxy1 {
server 10.0.205.53:8080;
server 10.0.205.50:8080;
}
server {
listen 80 default_server;
server_name _;
access_log /etc/nginx/logs/nginx_access.log;
error_page 404 /404.html;
location = /404.html {
root /usr/share/nginx/html;
}
error_page 500 502 503 504 /50x.html;
location = /50x.html {
root /usr/share/nginx/html;
}
######################################################
######################################################
location / {
proxy_pass http://proxy1/IdeaVodaPanel/;
#include /etc/nginx/conf.d/proxy_var;
#include /etc/nginx/conf.d/en_compress;
}
}
23

24. Dhruba Mandal
2. Least – Connected : As the name suggests, the incoming request will be
sent to the server that has the less number of connection.
For this, add the keyword “least_conn” at the top of the upstream as shown
below rest will be same as round robin configuration
If you have several servers listed in the least_conn, and if multiple servers are having the
similar low number of existing active connections, then among those servers, one will be
picked based on weighted round-robin.
Note : - The disadvantage of the round-robin and least-connected method is that
subsequent connection from the client will not go to the same server in the pool .
This may be Ok for a non session dependent application But if your application is
dependent on session, then once an initial connection is established with a particular
server, then you want all future connection from that particular client to go to the same
server. 24

25. Dhruba Mandal
3. The ip_hash method : . ip-hash – This is helpful when you want to have
persistence or stick connection of the incoming request. In this type, the client’s
ip-address is used to decide which server the request should be sent to.
Specifies that a group should use a load balancing method where requests are
distributed between servers based on client IP addresses.
The first three octets of the client IPv4 address, or the entire IPv6 address, are used as
a hashing key.
The method ensures that requests from the same client will always be passed to the
same server except when this server is unavailable.
upstream proxy1 {
ip_hash;
server 10.0.205.53:8080;
server 10.0.205.50:8080;
}
If one of the servers needs to be temporarily removed, it should be marked with the
down parameter in order to preserve the current hashing of client IP addresses. Fig
(B)
upstream proxy1 {
ip_hash;
server 10.0.205.53:8080;
server 10.0.205.50:8080;down;
}
Fig : A Fig : B 25

26. Weight Options for the Individual Servers
Dhruba Mandal
You can also specify a weight for a particular server in your pool. By default, all the
servers has the equal priority (weight). i.e. The default value of weight is 1.
But, you can change this behavior by assigning a weight to a server as shown below.
upstream proxy1 {
server 10.0.205.53:8080;
server 10.0.205.50:8080;
server 192.168.101.3:8080 weight 2;
server 192.168.101.4:8080;
server 192.168.101.5:8080;
}
In this example, we have total of 5 servers. But the weight on 3rd server is 2. This
means that for every 6 new request, 2 request will go to 3rd server, and rest of the
server will get 1 request.
you can use weight for least_conn and ip_hash also.
26

27. Timeout Options for the Individual Servers
(max_fails and fail _timeout)
Dhruba Mandal
We can also specify max_fails and fail timeout to a particular server as shown below
upstream proxy1 {
server 10.0.205.53:8080 max_fails=3
fail_timeout=30s;
server 10.0.205.50:8080;
server 192.168.101.3:8080 weight 2;
server 192.168.101.4:8080;
server 192.168.101.5:8080;
}
The default fail_timeout is 10 seconds. however in example this is set to 30 seconds. This
means that within 30 seconds if there were x number of failed attempts (as defined by
max_fails), then the server will be unavailable. Also, the server will remain unavailable for
30 seconds.
The default max_fails is 1 attempt. this is also set to 3 attempts. This means that after 3
unsuccessful attempts to connect to this particular server, Nginx will consider this server
unavailable for the duration of fail_timeout which is 30 seconds.
27

28. Backup Server in Nginx Load Balancer Pool
Dhruba Mandal
upstream proxy1 {
server 10.0.205.53:8080 max_fails=3
fail_timeout=30s;
server 10.0.205.50:8080;
server 192.168.101.3:8080 weight 2;
server 192.168.101.4:8080;
server 192.168.101.5:8080 backup;
}
In above example, the 5th server is marked as backup using “backup” keyword
at the end of server parameter.
On this 5th server (192.168.101.5) as a backup server. Incoming request will
not be passed to this server unless all the other 4 servers are down
28

29. Nginx Reverse Proxy
Dhruba Mandal 29
A reverse proxy is a server that sits between internal applications and external clients,
forwarding client requests to the appropriate server.

30. Benefit of Nginx Reverse Proxy
Dhruba Mandal 30
Load Balancing - A reverse proxy can perform load balancing which helps distribute
client requests evenly across backend servers.
Increased Security - A reverse proxy also acts as a line of defense for your backend
servers
Better Performance - Nginx has been known to perform better in delivering static
content over Apache. Therefore with an Nginx reverse proxy, all client requests can be
handled by Nginx while all requests for dynamic content can be passed on to the backend
Apache server.
Server cached content : reverse proxies can also be used to serve cached content , hence
making faster data available.
Easy Logging and Auditing - Since there is only one single point of access when a reverse
proxy is implemented, this makes logging and auditing much simpler

31. Configuration NGINX As Reverse Proxy
Dhruba Mandal 31
1.Install Nginx ( for configuration refer slide no 15 )
2. If you are running a firewall, run the following commands to allow HTTP and HTTPS
traffic:
sudo firewall-cmd --permanent --zone=public --add-service=http
sudo firewall-cmd --permanent --zone=public --add-service=https
sudo firewall-cmd --reload
3. Enable Nginx to start when your system boots with below command
sudo systemctl enable nginx
4. Go to path /etc/nginx/conf.d
a. create a file inside it with any name but .conf for example here I am creating file
with name reverse.conf

32. Dhruba Mandal 32
5 . Open the file by vim filename and add the below configuration lines
vim reverse.conf
server {
listen 80;
listen [::]:80;
server_name mongod1;# YOUR DOMAIN NAME
location / {
proxy_redirect off;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_set_header Host $host;
proxy_pass http://10.0.205.53:9100;# YOUR TOMCAT IP ADDRESS and port
In above mongod1 is my computer domain name and 10.0.205.53 is my IP and
9090 is my port .

33. Dhruba Mandal 33
6 . In your main nginx config file (i.e. nginx.conf) add the path of your directory where
configuration file is (in our case it is located at /etc/nginx/conf.d/ ) so we have included
/etc/nginx/conf.d/*.conf; expect below shown like comment all other line using #)
user nginx;
worker_processes auto;
error_log /var/log/nginx/error.log;
pid /run/nginx.pid;
events {
worker_connections 1024;
}
http {
log_format main '$remote_addr - $remote_user [$time_local] "$request" '
'$status $body_bytes_sent "$http_referer" '
'"$http_user_agent" "$http_x_forwarded_for"';
access_log /var/log/nginx/access.log main;
sendfile on;
tcp_nopush on;
tcp_nodelay on;
keepalive_timeout 65;
types_hash_max_size 2048;
include /etc/nginx/conf.d/*.conf;
default_type application/octet-stream;
}
Now check configuration using nginx –t and restart your nginx by command
systemctl restart nginx

34. References
https://www.linode.com/docs/web-servers/nginx/nginx-installation-and-basic-setup/
https://www.digitalocean.com/community/tutorials/understanding-the-nginx-
configuration-file-structure-and-configuration-contexts
https://www.youtube.com/watch?v=1ndlRiaYiWQ
https://www.youtube.com/watch?v=1ndlRiaYiWQ
https://www.youtube.com/watch?v=bfd05_vaWJE
https://nginx.org/en/docs/http/ngx_http_upstream_module.html#ip_hash
https://www.thegeekstuff.com/2017/01/nginx-loadbalancer/
Dhruba Mandal 34
Dhruba Mandal
Email :dhruvmandal@gmail.com