finaldzn / go-simple-udp-server

A simple UDP Server demo app written by Golang; and the way how to dockerize it from `scratch`

Simple UDP Server Written By Go

It's just a simple demo app to demonstrate how to write a simple UDP Server by using Golang.

Get Started

Start It Up

$ go run *.go
UDP Server listening on: :8888

Or specify the -address:

$ go run *.go -address=0.0.0.0:5678
UDP Server listening on: 0.0.0.0:5678

Play With It

Assuming the UDP Server is listening on local machine's 0.0.0.0:5678):

$ go run *.go -address=0.0.0.0:5678
UDP Server listening on: 0.0.0.0:5678

Open another console to play with it.

UDP Testing Client Console, we can simply use nc to test it. We can key in any string and then hit Enter, in client side it will echo back and print exactly what we keyed in. For example, if we key in A then Enter, and then B then Enter, we shall see something like:

$ nc -u 127.0.0.1 5678
A
A
B
B

If you look at the Console for UDP Server, you shall see some logs like:

$ go run *.go -address=0.0.0.0:5678
UDP Server listening on: 0.0.0.0:5678
Packet Received: [2] bytes from [127.0.0.1:51959]
Packet Written: [2] bytes to [127.0.0.1:51959]
Packet Received: [2] bytes from [127.0.0.1:51959]
Packet Written: [2] bytes to [127.0.0.1:51959]

Dockerize It

1. Build

$ sed 's/${PORT}/5678/g' Dockerfile > Dockerfile.build \
    && docker build --rm -t itstarting/go-simple-udp-server -f Dockerfile.build . \
    && rm Dockerfile.build

Note: as there is a known issue that ARG and ENDPOINT don't work well (see here), have to do some trick like above.

2. Check

$ docker images
REPOSITORY                                      TAG                 IMAGE ID            CREATED             SIZE
itstarting/go-simple-udp-server                 latest              5d43f270df0c        6 minutes ago       2.07MB

Note: yeah, it's just ~2MB!

3. Run

$ docker run -p 5678:5678/udp itstarting/go-simple-udp-server

Ref

• Good read (actually the code was borrowed from it): https://ops.tips/blog/udp-client-and-server-in-go/