Basic setup for projects with Golang

Hi everybody! In this post, I’m going to explain how to create a Golang project with Docker. Video en español en mi canal.

PART 2.

This repository contains the code.

Requirements

• Docker installed
• Basic knowledge with docker
• Docker compose installed

Structure project

The structure for this project is very simple.

• app: Contains all the files of our application.
• main.go: Application entry point.
• Dockerfile: Dockerfile to build our image.
• docker-compose.yml: File to help build our image more easily.
• go.mod: File to track your project dependencies.

your-folder-project
    app
       main.go
       run.sh
       go.mod
    Dockerfile
    docker-compose.yml

Dockerfile

FROM golang:1.22.3-bullseye

ENV APP_ENV prod
ENV WORDIR_APP /usr/src
ENV BINARY_NAME main
ENV BINARY_PATH ${WORDIR_APP}/${BINARY_NAME}

WORKDIR ${WORDIR_APP}
COPY app/go.mod app/run.sh ./

RUN go mod download && \
    go mod verify && \
    go install github.com/cosmtrek/air@v1.51.0

WORKDIR ${WORDIR_APP}/app

COPY ./app .

RUN go build -v -o ${BINARY_PATH}

CMD [ "bash", "run.sh" ]

In this file we define image version FROM golang:1.22.3-bullseye. Then there are 4 environments.

• APP_ENV: This environment is used to manage the mode in which our application is running. We use values like: (prod, develop, test).
• WORDIR_APP: It is the location when we are working.
• BINARY_NAME: This is the name of our application when it is finally built. You can use any name that you want.
• BINARY_PATH: This is the full path of our binary when the application is built.

On line 11, we’re installing all dependencies in our project, and additionally, we add this library to enable live-reload functionality in our application.

I think that was the most important thing in Dockerfile.

go.mod

This file is to track dependencies in your project. You can check the basic tutorial.

module example/demogo

go 1.22.3

• module: The name of your package.
• go: Golang version. In this case this version must be the same one that we use in our Dockerfile

run.sh

#!/bin/bash

echo "=== Start app in (${APP_ENV}) ==="

env=${APP_ENV:-}

if [ "$env" = "prod" ]; then
    # exucute binary
    ${BINARY_PATH} 
else
    air --build.cmd "go build -v -o ${BINARY_PATH}" --build.bin "${BINARY_PATH}"
fi

In this file, we have a conditional to execute a command depending on whether APP_ENV is prod or develop. If APP_ENV is prod, it executes the binary that we previously compiled in our Dockerfile. Otherwise, we execute the air command to use live reload in our app.

docker-compose.yml

version: '3'
services:
  demogolang:
    build: .
    environment:
      - APP_ENV=develop
    volumes:
      - ./app:/usr/src/app

Start app

To start our application we only have to execute the following command: docker compose up.