Nginx Load Balancing with Forward Proxy

Nginx, the famous Nginx! It is a powerful open source software, proudly known for its high performance and stability. It can do a lot of things like Nginx load balancing and can also be used in conjunction with forward proxies to make your online world more accessible.

I. Nginx load balancing

Load balancing, it has to be said, is a headache for many IT engineers. Suppose you have a server which is too busy to cope with the huge number of visits from the web, what to do then?Nginx load balancing came into being, which acts like a magical arbiter that can evenly distribute requests from users to different servers, thus reducing the load pressure on a single server.

There are various load balancing modules for Nginx, the most commonly used of which is the ip_hash algorithm. This algorithm assigns requests to back-end servers based on the user's IP address. This approach ensures that requests from the same user are sent to the same server, which is useful in many application scenarios, such as online gaming or shopping sites.

II. Positive proxy

Next, let's talk about forward proxies. Forward proxy, as opposed to reverse proxy, means that the proxy server is located between the client and the target server, and the client sends requests to the target server through the proxy server, thus realizing the purpose of hiding the real client's IP address and so on. This concept is very useful for some scenarios that require proxy access, such as surfing the web or multinational website access.

When using Nginx as a forward proxy, we need to configure the parameters related to reverse proxy. First, we need to add the following configuration under the http module:

http {
...
proxy_pass http://your_target_server; proxy_set_header Host $host; proxy_set_header
proxy_set_header Host $host.
...
}

This way, when a user sends a request, Nginx will proxy the request and forward it to the target server. Also, we can set some HTTP header information that will be passed to the target server, such as Host, with the proxy_set_header directive.

III. Combined use

Now that we know a little bit about both Nginx load balancing and forward proxying, let's talk about how to use them together. First, we need to add the following configuration to our Nginx.conf configuration file:

http {
...
upstream backend {
server backend1.example.com; server backend2.example.com; server backend2.example.com; server backend2.example.com
server backend2.example.com; server backend3.example.com; server backend4.example.com; server backend5.example.com
upstream backend { server backend1.example.com; server backend2.example.com; server backend3.example.com; ...
...
}
...
server {
...
location / {
proxy_pass http://backend; proxy_set_header Host $host; proxy_set_header
proxy_set_header Host $host.
}
...
}
...
}

In this configuration, we define a cluster of servers called backend. In the cluster, we can add multiple backend servers, which can be the same or different. This way, when a user sends a request, Nginx will distribute the request to the backend servers in a load balanced manner.

At the same time, we set the forward proxy related parameters in the location section of the server block, specifying the address to forward the request to the backend server and passing the HTTP headers. In this way, Nginx implements both load balancing and forward proxying.