Tag Network

The varnish is a well-known HTTP accelerator. As the continuation of the GoInPractice series, today I’ll show how you can build a simple (and naive) varnish implementation in Go. Some of the code is reused from Writing a reverse proxy so if you don’t understand something, I recommend taking a look at the blog post.

We’ll split our project into a few parts. The first one will be the caching mechanism. Its responsibility will be storing the data to cache and invalidate it after reaching the deadline. We’ll use mutexes for synchronization between goroutines.

Some time ago, I found a video called Building a DIY proxy with the net package. I recommend watching it. Filippo Valsorda builds a simple proxy using low-level packages. It’s fun to watch it but I think it’s a bit complicated. In Go, it has to be an easier way so I decided to continue writing series Go In Practice by writing a simple but yet powerful reverse proxy as fast as it’s possible.

Go is perfect for network applications. Its awesome standard library helps a lot in writing such software. In this article, we’ll write a simple TCP scanner in Go. The whole programm will take less than 50 lines of code. Before we’ll go to practice - a little theory.

Of course, the TCP is more complicated than I describe but we need just basics. The TCP handshake is three-way. Firstly, the client sends the syn package which signals the beginning of a communication. If the client gets a timeout here it may mean that the port is behind a firewall.