uploading files to S3 via Golang is one of the most common operations when it comes to managing files on AWS. This functionality allows developers to upload documents, images, videos and other types of files to cloud storage in a secure and scalable way. In this article, we will explore how to perform this integration using the Go language and the AWS S3 API. Next, you will understand the main steps to configure your environment and upload successfully.

Preparing the Development Environment

Before you start uploading files, you need to configure your development environment. Make sure you have:

1. A valid AWS account.
2. The access credentials (access key and secret key) for your AWS account.
3. Go SDK installed.
4. The official AWS SDK for Go package.

To install the AWS SDK for Go, simply run the following command:

go get -u github.com/aws/aws-sdk-go/aws

Now that the SDK is installed, you are ready to start writing AWS S3 integration code.

See how to lifecycle s3 using Lambdas to automate this work: https://devopsmind.com.br/aws-pt-br/automacao-aws-s3-lifecycle-lambda/

Uploading to S3

Configuring the AWS S3 Client

The first step to upload is to configure the AWS S3 client. This client allows you to interact with the AWS service and manage your buckets and objects. The following code shows how to configure the client using your credentials:

import (
    "github.com/aws/aws-sdk-go/aws"
    "github.com/aws/aws-sdk-go/aws/session"
    "github.com/aws/aws-sdk-go/service/s3"
)

func createS3Client() *s3.S3 {
    sess := session.Must(session.NewSession(&aws.Config{
        Region: aws.String("us-west-2"),
    }))
    return s3.New(sess)
}

In this code, we create an AWS session and configure the S3 client. Don't forget to replace the region with the location where your S3 bucket is configured.

Creating the Upload Function

After configuring the AWS S3 client, we will create the function responsible for uploading the files. This function will read the file from the local system and send it to S3, within a specific bucket:

import (
    "fmt"
    "os"
    "github.com/aws/aws-sdk-go/aws"
    "github.com/aws/aws-sdk-go/aws/session"
    "github.com/aws/aws-sdk-go/service/s3"
)

func uploadFileToS3(bucketName, filePath, key string) error {
    file, err := os.Open(filePath)
    if err != nil {
        return err
    }
    defer file.Close()

    sess := session.Must(session.NewSession(&aws.Config{
        Region: aws.String("us-west-2"),
    }))

    uploader := s3.New(sess)
    _, err = uploader.PutObject(&s3.PutObjectInput{
        Bucket: aws.String(bucketName),
        Key:    aws.String(key),
        Body:   file,
    })

    if err != nil {
        return fmt.Errorf("falha no upload para o S3: %v", err)
    }
    fmt.Println("Upload realizado com sucesso!")
    return nil
}

Here, the uploadFileToS3 function receives three parameters: the bucket name, the local file path and the key (name) that the file will have in S3. The function opens the file and sends it to the bucket using the AWS S3 SDK for Go PutObject function.

Dealing with Permissions

When working with uploads to AWS S3, it is important to ensure that your permissions are configured correctly. AWS uses the IAM (Identity and Access Management) policy system to manage access permissions to its resources. Ensure that the IAM user or role being used in the code has sufficient permissions to perform upload operations to S3. For more details on IAM permissions, see the official AWS documentation.

Practical Usage Examples

Sending Images to an S3 Bucket

Let's assume you want to create a service where users can upload images and store them in an S3 bucket. The code would look similar to the following:

func main() {
    err := uploadFileToS3("meu-bucket", "caminho/para/imagem.png", "imagem.png")
    if err != nil {
        fmt.Println("Erro ao fazer upload:", err)
        return
    }
    fmt.Println("Upload concluído com sucesso!")
}

In this example, the image imagem.png will be uploaded to the my-bucket bucket. The path to the file and its name on S3 are defined by the parameters of the uploadFileToS3.

Conclusion

Uploading files to AWS S3 with Golang is a simple task when you use the correct tools. With the AWS SDK for Go, you can easily integrate your application with the S3 service, providing a robust and scalable file storage solution. Now that you've learned the basics, you can expand your implementation to include other functionality, such as downloading files, listing objects in the bucket, and more. Continue exploring more integration possibilities with AWS using Golang and check out more content about Golang and AWS S3.