Introduction to Go Fiber

What is go fiber?

Fiber is a web framework heavily inspired by Express and that makes it perfect to work with for node developers.

It is built on top of Fasthttp engine, here are some benchmarks. It also has quite a low memory allocation overhead. For example while writing this article it only took around only ~16mb of memory, which was amazing!

In this article let's implement very simple mock api routes to get a feel of the Fiber framework

The code from the article is available in this repository

Getting started

You can install go directly on your system by installing the binary from go docs https://golang.org/doc/install

(optional)

Personally, I like to use docker so I don't have to install anything on my system

Let's pull the golang docker image

docker pull golang

Create your project directory

mkdir go-mock-api
cd go-mock-api

Now we'll bind the port 4000 and mount the current directory (your go project dir) as volume and run our golang image

docker run -itd -p 4000:4000 --name golang -v "$(pwd):/app" golang

Let's run and connect to our running golang container

docker exec -it -w /app golang bash

This should drop us into the golang docker image. Now let's check the version of go and get started

go version

Note: if you're using docker, all the step below are executed inside the golang container

Installation

Let initialise an api module

go mod init api

Install fiber

go get -u github.com/gofiber/fiber/v2

Let's create api.go with a sample hello world server on port 4000 as shown in the repository's readme.

package main

import "github.com/gofiber/fiber/v2"

func main() {
    app := fiber.New()

    app.Get("/", func(ctx *fiber.Ctx) error {
        return ctx.SendString("Hello, World!")
    })

    app.Listen(":4000")
}

Development

Reflex helps with live reload for Go apps, which is great for development. It is quite similar to nodemon, alternatively, you can simply use go run command to run your program.

go get github.com/cespare/reflex

Let's start!

reflex -g '*.go' go run api.go --start-service

Starting service...

 ┌───────────────────────────────────────────────────┐ 
 │                   Fiber v2.13.0                   │ 
 │               http://127.0.0.1:4000               │ 
 │       (bound on host 0.0.0.0 and port 4000)       │ 
 │                                                   │ 
 │ Handlers ............. 2  Processes ........... 1 │ 
 │ Prefork ....... Disabled  PID .............. 3315 │ 
 └───────────────────────────────────────────────────┘

Note: Make sure you have PATH exported in your .bashrc or .zshrc file as export PATH=$PATH:$HOME/go/bin/

Now you should be seeing your code running and it should auto reload when you change something, without having to re-run your go program!

Creating a GET route

Let's import fiber

import "github.com/gofiber/fiber/v2"

Add a user route to the main function

app.Get("/user", getUserHandler)

Let's add getUserHandler which will handle the request. Here we will return a mock user.

type User struct {
    Name    string `json:"name"`
    Twitter string `json:"twitter"`
}

func getUserHandler(ctx *fiber.Ctx) error {
    user := User{
        Name:    "Karan",
        Twitter: "karan_6864",
    }

    return ctx.Status(fiber.StatusOK).JSON(user)
}

Creating a POST route

Similarly, let's add a post route to the main function

    app.Post("/user/create", createUserHandler)

Let's add a createUserHandler which will handle the request. Here we will simply parse the body and send it back in the response

func createUserHandler(ctx *fiber.Ctx) error {
    body := new(User)
    err := ctx.BodyParser(body)

    if err != nil {
        ctx.Status(fiber.StatusBadRequest)
        return err
    }

    user := User{
        Name:    body.Name,
        Twitter: body.Twitter,
    }

    return ctx.Status(fiber.StatusOK).JSON(user)
}

Middleware

Let's add logging middleware that comes with fiber

import (
    "github.com/gofiber/fiber/v2/middleware/logger"
)

Add this middleware to main function

app.Use(logger.New())

This should give us some logs as shown below

12:04:01 | 200 |     1ms |      172.17.0.1 | GET     | /user           
12:04:27 | 200 |      0s |      172.17.0.1 | POST    | /user/create

We can define custom middlewares as well

    app.Use(func(ctx *fiber.Ctx) error {
        fmt.Println("Sample middleware")
        return ctx.Next()
    })

Router

We can organize our routes with Group function, very similar to how we do routing in express.

    userApi := app.Group("/user")

    userApi.Get("/", getUserHander)

    userApi.Post("/create", createUserHandler)

Serving static file

Let's assume we're trying to server public folder, we can simply use the Static function like below

app.Static("/", "./public")

Let's try it out!

Here's our final api.go

package main

import (
    "fmt"

    "github.com/gofiber/fiber/v2"
    "github.com/gofiber/fiber/v2/middleware/logger"
)

type User struct {
    Name    string `json:"name"`
    Twitter string `json:"twitter"`
}

func getUserHander(ctx *fiber.Ctx) error {
    user := User{
        Name:    "Karan",
        Twitter: "karan_6864",
    }

    return ctx.Status(fiber.StatusOK).JSON(user)
}

func createUserHandler(ctx *fiber.Ctx) error {
    body := new(User)
    err := ctx.BodyParser(body)

    if err != nil {
        fmt.Println(err)
        ctx.Status(fiber.StatusBadRequest)
        return err
    }

    user := User{
        Name:    body.Name,
        Twitter: body.Twitter,
    }

    return ctx.Status(fiber.StatusOK).JSON(user)
}

func main() {
    app := fiber.New()

    app.Use(logger.New())

    userApi := app.Group("/user")

    userApi.Get("/", getUserHander)

    userApi.Post("/create", createUserHandler)

    app.Listen(":4000")
}