Setting Up Nginx in a Docker Container as a Load Balancer

Introduction

In this tutorial, you'll learn how to configure an Nginx Docker container to function as a load balancer. This setup will distribute incoming requests to two application instances in a round-robin manner.

Prerequisites

Ensure you have the following:

• Docker installed
• Basic knowledge of Nginx and Docker

Application Instances

We have two instances of the application running on:

• 192.168.1.250:2221
• 192.168.1.250:3331

Requests arriving at the Nginx server on port 8080 will be forwarded to these instances.

Nginx Configuration (nginx.conf)

Create a configuration file for Nginx to handle load balancing.

http {
    upstream all {
        server 192.168.1.250:2221;
        server 192.168.1.250:3331;
    }

    server {
         listen 8080;
         location / {
              proxy_pass http://all/;
         }
    }
}

events { }

Dockerfile (Dockerfile)

Create a Dockerfile to build the Nginx image with your configuration.

FROM nginx
COPY nginx.conf /etc/nginx/nginx.conf

Building and Running the Docker Container

Follow these steps to build and run your Nginx load balancer container:

1. Create a directory for your Nginx load balancer and navigate into it:

   mkdir nginx-load-balancer
   cd nginx-load-balancer
   

2. Create the nginx.conf and Dockerfile with the configurations above.

3. Build the Docker image:

   docker build -t nginxlb .
   

4. Run the Docker container:

   docker run -d --name nginx-load-balancer -p 8087:8080 nginxlb
   

Conclusion

Your Nginx container is now set up to balance the load between two application instances. This setup will improve application reliability and scalability.