golang S3 upload module with gzip file compression

s3_uploader.go

package uploader

import (
	"bytes"
	"compress/gzip"

	"myapp/internal/config"
	"github.com/aws/aws-sdk-go/aws"
	"github.com/aws/aws-sdk-go/aws/session"
	"github.com/aws/aws-sdk-go/service/s3/s3manager"
)

type UploadFileParams struct {
	Compression string
	Key         string
	Contents    []byte
}

func UploadFile(params UploadFileParams) error {
	cfg := config.AppConfig()

	if cfg.BucketName == "" || params.Key == "" {
		// no bucket or key, no upload attempted
		return nil
	}

	sess, err := session.NewSession(&aws.Config{
		Endpoint: aws.String(cfg.StorageEndpoint),
	})

	if err != nil {
		return err
	}

	body := params.Contents

	// compress contents, if needed
	if params.Compression == "gzip" {
		body, err = compressBytes(body)
		if err != nil {
			return err
		}
	}

	// upload to storage
	uploader := s3manager.NewUploader(sess)
	_, err = uploader.Upload(&s3manager.UploadInput{
		Bucket: aws.String(cfg.BucketName),
		Key:    aws.String(params.Key),
		Body:   bytes.NewReader(body),
	})

	if err != nil {
		return err
	}

	return nil
}

func compressBytes(contents []byte) ([]byte, error) {
	var buf bytes.Buffer

	// compress bytes
	zw := gzip.NewWriter(&buf)
	_, err := zw.Write(contents)

	if err != nil {
		return nil, err
	}

	// close writer
	if err := zw.Close(); err != nil {
		return nil, err
	}

	return buf.Bytes(), nil
}