Let's Get Started with Echo, Go, AWS SDK for GO, and AWS S3

Preparation

We need to prepare some tools, such as:

1. Go. You may download it here. In this post, I use Go 1.18.
2. Your Favorite IDE (Integrated Development Environment).
3. Postman. You may download here. Feel free to use other similar tools.

Setup AWS S3 and IAM User

• Open AWS Console
• Search S3 in the search bar. Click the S3.

• Click Create bucket

• Fill in the bucket name and select AWS region. After that, click Create bucket.

Note: We let the config as it is. You may configure it.

• Go to IAM -> Users.

• Create a new user. We will create a user that will have a responsibility to upload the files. Click Add User.

• Fill in the user name and tick the Access key - Programmatic access

• Click Next. We will setup the permission. For now, we will use AmazonS3FullAccess. You may setup custom permissions to achieve the least privilege.

• You may configure other settings and create a user.

• After that, copy and save the credentials. You will use this later.

Time to Code

• Prepare a folder/directory for your project.

• Open the terminal (make sure the current directory is your project). Initiate go module. Run go mod init <project name>, example: go mod init explore-go.

• Add our dependencies. First I add Echo. go get github.com/labstack/echo/v4

• Add AWS SDK and S3 service.
  

go get github.com/aws/aws-sdk-go-v2
go get github.com/aws/aws-sdk-go-v2/config
go get github.com/aws/aws-sdk-go-v2/service/s3
go get github.com/aws/aws-sdk-go-v2/feature/s3/manager

• Create file server.go with code below. Don't forget to change the bucket name.

package main

import (
    "context"
    "mime/multipart"
    "net/http"

    "github.com/aws/aws-sdk-go-v2/aws"
    "github.com/aws/aws-sdk-go-v2/config"
    "github.com/aws/aws-sdk-go-v2/feature/s3/manager"
    "github.com/aws/aws-sdk-go-v2/service/s3"
    "github.com/labstack/echo/v4"
    "github.com/labstack/echo/v4/middleware"
)

type UploadResult struct {
    Path string `json:"path" xml:"path"`
}

func upload(c echo.Context) error {
    file, err := c.FormFile("file")
    if err != nil {
        return err
    }
    src, err := file.Open()
    if err != nil {
        return err
    }
    defer src.Close()
    result, err := UploadToS3(c, file.Filename, src)
    if err != nil {
        return err
    }
    data := &UploadResult{
        Path: result,
    }
    return c.JSON(http.StatusOK, data)
}

func UploadToS3(c echo.Context, filename string, src multipart.File) (string, error) {
    logger := c.Logger()
    cfg, err := config.LoadDefaultConfig(context.TODO())
    if err != nil {
        logger.Fatal(err)
        return "", err
    }
    client := s3.NewFromConfig(cfg)
    uploader := manager.NewUploader(client)
    result, err := uploader.Upload(context.TODO(), &s3.PutObjectInput{
        Bucket: aws.String("<change this with your bucket name>"),
        Key:    aws.String(filename),
        Body:   src,
    })
    if err != nil {
        logger.Fatal(err)
        return "", err
    }
    return result.Location, nil
}

func main() {
    e := echo.New()
    e.Use(middleware.Logger())
    e.GET("/", func(c echo.Context) error {
        return c.String(http.StatusOK, "Hello, World!")
    })
    e.POST("/upload", upload)

    e.Logger.Fatal(e.Start(":1323"))
}

• Setup environment variable.

(For Linux)

export AWS_REGION=<change with your region>
export AWS_ACCESS_KEY_ID=<change with your key id>
export AWS_SECRET_ACCESS_KEY=<change with you access key>

You can use any name but I recommend the name of the file .env.sh. After that run the file using source .env.sh.

(For Windows)

set AWS_REGION=<change with your region>
set AWS_ACCESS_KEY_ID=<change with your key id>
set AWS_SECRET_ACCESS_KEY=<change with you access key>

You can use any name but I recommend the name of the file env.bat. After that run the file using env.bat.

• Run our server. go run server.go.

• Call our API with Postman. Make sure you fill correct address bar, HTTP method, and body. After that click Send.

• If successful, you will get a message like this in the console.

• Open S3. Make sure your file is in there.

Github Project

berviantoleo / explore-go

Exploring Go

Explore Go (explore-go)

Blog Post

Part of this post: Dev.to

Development

Prepare Dependencies

go get
go install

Run

go run server.go

Build

go build

Test

go test ./...

Test and Check Coverage

go test ./... -covermode=atomic -coverprofile cover.out

License

BSD 3-Clause

View on GitHub

Awesome

You are awesome!

GIF Image Source: https://i.giphy.com/media/vCKC987OpQAco/giphy.gif

If you have any questions or problems, feel free to ask for help.

Thank you.

Comments

[ALTA-BE12-Lukmanul Khakim]

where do we save the environment variable and what is the filename like, thanks you

[Bervianto Leo Pratama]

in the root of the project, same directory with server.go.

the filename:

• Linux

.env.sh

• Windows (CMD)

env.bat