Exposing Docker applications with Nginx

Written by: Cristina Rancaño

In this post we want to share some basic examples of how to use Nginx to expose applications running in Docker.

To start, we give a quick overview of the services we are going to see:

• Nginx: is an open-source web server that is also used as a reverse proxy, HTTP cache, and load balancer.

• Docker: is an open-source tool that allows developers to create, deploy, run, and manage containers.

Required Software

• A Linux server (In the example, we will use one based on Debian)

• Nginx installed: apt update && apt install nginx

• Docker installed: docu.

Nginx with Docker

This is the infrastructure we will set up:

• 2 applications running in docker:

  • App1 - which exposes port 1234

  • App2 - which exposes port 1235

• An Nginx server where we will have the following domains:

  • app1.test.com

  • app2.test.com

To understand this, first we need to see the following:

• Thanks to Nginx Vhosts we are redirecting traffic and requests to our containers.

• Each Vhost has its own configuration, usually found in:

  /etc/nginx/sites-available → are the available vhosts on our server.

  /etc/nginx/sites-enabled → are the active vhosts, usually symbolic links to the previous directory.

In this example, we will see a basic configuration for each of the Vhosts. For example, we will configure the listener, the hostname, and the corresponding proxy. Example:

Vhost for App1

server {
    listen 80;
    server_name app1.test.com;

    location / {
        proxy_pass http://localhost:1234;
        # Otras configuraciones
    }
}

Vhost for App2

server {
    listen 80;
    server_name app2.test.com;

    location / {
        proxy_pass http://localhost:1235;
        # Otras configuraciones
    }
}

Possible Errors

• Port conflict: It is important to note that each container must have a different port than the host.

• The ports of the applications must be different from the Nginx web server port.

Nginx with Docker and system services

In addition to configuring Vhosts that lead to containers, we can also direct traffic to services running on the system itself.

Vhost for App3

server {
    listen 80;
    server_name app3.test.com;

    location / {
        proxy_pass http://localhost:8080;
        # Otras configuraciones
    }
}

Summary

In this post, we have different basic examples of how with Nginx we can direct traffic to containers and also to services running within our server. We hope you found it useful.

Thank you for reading!