How to Run Your Go Application Using Docker? 🐋

In the last decade, Docker has become popular as a development mechanism thanks to its many advantages such as:

• Small development environments with the minimum needed to run.
• Being able to share them easily without worrying about dependencies.
• Various cloud services use them as standard to run your application easily.
• Easy and intuitive syntax to declare our container configuration.

Therefore, today we'll create a Go application that will be executed from a Docker container. This will be the first part of a tutorial where we'll deploy an API made in Go to Google Cloud ☁️.

Creating Our Project

For this we'll open a terminal and navigate to the folder where we want to create our project. In my case, my folder is Development.

Once inside the folder we'll create a new project:

~
mkdir fiber-docker

Inside this folder we'll initialize Go modules to manage our Go project dependencies.

~
go mod init github.com/solrac97g/fiber-docker

Now we'll create a Go file that will be our main:

~
touch main.go

And we'll create our docker file

~
touch dockerfile

This will be the minimum we'll require to run our Go project for now.

Modifying the Main

Inside main we'll execute the following code which will set up an HTTP server using Fiber, a Go framework, and expose it on port 8080.

~

package main

import (
"github.com/gofiber/fiber/v2"
"log"
)

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

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

app.Get("/ping", func(c *fiber.Ctx) error {
	return c.SendString("pong")
})

log.Fatal(app.Listen(":8080"))
}

Don't forget to install our dependency. From the terminal we'll add the dependency to our project:

~
go get github.com/gofiber/fiber/v2

Now we have our code ready to work. What this script basically does is create two endpoints: the main one "/" which responds with "hello world" and "/ping" which responds with "pong".

Configuring Our Docker Container

To configure our Docker container we'll edit our dockerfile

~

FROM golang:1.18-alpine
WORKDIR /app
COPY go.mod .
COPY go.sum .
RUN go mod download
COPY . .
RUN go build -o ./out/dist .
CMD ./out/dist

What this does is create a container that runs Go 1.18, then copies the dependency files to the container and downloads the dependencies to finally build the project and execute it.

Running Our Project

Finally we can run our container using the following command first to build our container.

~
docker build -t app .

And now the following command to start our container.

~
docker run -p 8888:8080 app

Our project will be ready to receive requests from the URL: http://localhost:8888