‘Hello, World!’ Application: How to Dockerize Golang Application

Do you struggle to begin with Docker? Would you like to be the one to dockerize a Golang app effectively? Are you having difficulty determining a basic tutorial for dockerizing a Golang app? Each of these queries and only one solution – yes, you've picked the best tutorial!

For beginners,this tutorial will be really useful. In this guide, we will design an app by showing some basic steps to dockerize the golang app. Without any more hesitation, let's begin our tutorial.

Dockerization of a Golang App Requirements

Once you start developing the app, assure that your system has docker and golang set up. If not, follow the instructions to install it.

⦿ Install Docker

⦿ Install Golang

Setup of the Project

First and foremost, let's make the main.go file using the command go mod init, create and restart the app.

The project structure will be as follows:

sample-dockerize-app

|– main.go

|– Dockerfile

Main.go will contain the code mentioned below.

package main

import (

"encoding/json"

"fmt"

"log"

"net/http"

"github.com/gorilla/mux"

)

func main() {

router := mux.NewRouter()

router.HandleFunc("/", func(rw http.ResponseWriter, r *http.Request) {

response := map[string]string{

"message": "Welcome to Dockerized app",

}

json.NewEncoder(rw).Encode(response)

})

router.HandleFunc("/{name}", func(rw http.ResponseWriter, r *http.Request) {

vars := mux.Vars(r)

name := vars["name"]

var message string

if name == "" {

message = "Hello World"

} else {

message = "Hello " + name

}

response := map[string]string{

"message": message,

}

json.NewEncoder(rw).Encode(response)

})

log.Println("Server is running!")

fmt.Println(http.ListenAndServe(":8081", router))

}

Make a Docker Image.

According to the documentation, an image contains everything required to run an application, including the code, dependencies, and any other objects required.

An image defines your app that will be required for handling the app in the most basic terms.

You must write steps in the config file to create a Docker image. Dockerfile is the most common and preferred file name, but you can use any name you want. However, in my opinion, it is always preferable to adhere to standards.

Now, create a file named Dockerfile and write the following code.

# Build Stage

# First pull Golang image

FROM golang:1.17-alpine as build-env

# Set environment variable

ENV APP_NAME sample-dockerize-app

ENV CMD_PATH main.go

# Copy application data into image

COPY . $GOPATH/src/$APP_NAME

WORKDIR $GOPATH/src/$APP_NAME

# Budild application

RUN CGO_ENABLED=0 go build -v -o /$APP_NAME $GOPATH/src/$APP_NAME/$CMD_PATH

# Run Stage

FROM alpine:3.14

# Set environment variable

ENV APP_NAME sample-dockerize-app

# Copy only required data into this image

COPY --from=build-env /$APP_NAME .

# Expose application port

EXPOSE 8081

# Start app

CMD ./$APP_NAME

Run the code mentioned below and update the dependencies

go mod tidy

Build and Run Docker Image

To build the docker image Use the below code

docker build --rm -t golang-docker-example .

The output visible on your screen will look something like this

To run the image use the command mentioned below

docker run -p 8081:8081 golang-docker-example

To conclude, this was a beginner's tutorial about how to dockerize the Golang app with the help of an example of the "HELLO WORLD" application. If you want to learn in detail about this, you can refer to the link mentioned above, and if you are thinking of creating this kind of app, you should get in touch with the best Golang development company and hire golang developers from them.