Docker-nginx-lb

Nginx-lb is an extremely simple nginx-based load-balancer packaged in a Docker container. It accepts requests at specified port and distributes them over one or more backend servers.

In effect this project is a lightweight wrapper (~23 MB) over the nginx Docker image (the alpine variant). It is compatible with most options available present in those images.

Although in most cases it is better to use the plain nginx image, there are a couple of use cases where this image to create a load-balancer is useful:

1. When prototyping, where you just want to quickly bring up a basic load-balancer;
2. When working with a Docker environment that does not support volumes to mount a custom nginx.conf.

Usage

To proxy all requests to example.com:

docker run --rm --name example-nginx-lb \
  -p 9090:9090 \
  -e LB_PORT=9090 \
  -e LB_BACKENDS=example.com:80 \
  erwinvaneyk/nginx-lb:latest

You can use a simple curl command to see if it works:

curl -H "Host: example.com" http://localhost:9090

Configuration

On top of the configuration options of the plain nginx image, this image adds the following configuration options:

Environment Variable	Description	Default	Examples
LB_PORT	The port the LB should accept requests on.	80	443, 9090
LB_BACKENDS	The server(s) to which the LB should distribute the requests, semicolon-separated.	example.com:80	server1.example.com:3030;10.0.12.34:3031

Building

To build the Docker image yourself, you can use the plain Docker build workflow:

docker build --tag erwinvaneyk/nginx-lb:latest .