How to Setup Nginx

Motivation

Making sure of failover and load balancing mechanism in company products.

Diagram

Installation

Installing it on Ubuntu is just running this command:

sudo apt-get install nginx

Configurations

To check the simple scenario:

• Two Tomcat servers running a simple website.
• Nginx decides the failover and load balancing.

Configuration File

The default file I tried to edit:

server {
    listen 80 default_server;

    root /usr/share/nginx/html;
    index index.html index.htm;

    # Make site accessible from http://localhost/
    server_name localhost;

    location / {
        # First attempt to serve request as file, then
        # as directory, then fall back to displaying a 404.
        try_files $uri $uri/ =404;
        # Uncomment to enable naxsi on this location
        # include /etc/nginx/naxsi.rules

        # if localhost:80 get hit pass this to the following url 
        proxy_pass  http://localhost:8080/myapp/
    }
}

But still, it doesn’t show the proxy_pass path.

The Default File

# [Configuration details continue...]

Followed The Tutorial

But it doesn’t seem to work for me, it just gives me the default page of Nginx.

Load Balancing

For load balancing, upstream is used to define the servers. There are four types of load balancing Nginx provides:

1. Default (Round Robin)
2. Least Connected Load Balancing
3. Session Persistence
4. Weight Load Balancing

Simple Default (Round Robin) Configuration

http {
    upstream myapp1 {
        server srv1.example.com;
        server srv2.example.com;
        server srv3.example.com;
    }

    server {
        listen 80;

        location / {
            proxy_pass http://myapp1;
        }
    }
}

For Least Connected

upstream myapp1 {
    least_conn;
    server srv1.example.com;
    server srv2.example.com;
    server srv3.example.com;
}

For Session Persistence

upstream myapp1 {
    ip_hash;
    server srv1.example.com;
    server srv2.example.com;
    server srv3.example.com;
}

For Weight Load Balancing

upstream myapp1 {
    server srv1.example.com weight=3;
    server srv2.example.com;
    server srv3.example.com;
}

With this configuration, every 5 new requests will be distributed as follows: 3 requests to srv1, one request to srv2, and another one to srv3.

Reference: Nginx Load Balancing

Working Load Balancing Example

Assuming we have two servers: one is an app server and the other is a backup server.

Apache Servers LB for lb.site.com

# [Configuration details continue...]

Putting This in Location

/etc/nginx/site-enabled/lb-sites.com    

Link the File

ln -s /etc/nginx/sites-available/lb-site.com /etc/nginx/sites-enabled/

Then restart the Nginx Service or use a signal to reload the configurations. By default, it has round robin implemented. For other implementations, refer to the Nginx documentation.

Next Steps

We will do the following things:

• Testing SOAP services on Nginx.
• Building a high availability cluster using KeepAlived or Heartbeat.