文件已上传到s3，但不可见

I'm trying to upload an image to the s3 bucket using GoLang. I have mentioned function body of program. Which takes an image file as multipart form data and a file name which I should to save the image in s3.

func uploadImage(res http.ResponseWriter, req *http.Request) {
file, handler, err := req.FormFile("uploaded_file") // uploaded_file is the key(input field name) of the form-data
if err != nil {
    fmt.Println(err)
    return
}

type Resp struct {
    Status   string `json:"status"`
    Filename string `json:"filename"`
}
filename := req.Form.Get("filename")

rnd := render.New()
var Response Resp
Response.Status = "failed"
if filename != "" {
    // define credentials
    awsAccessKey := "KEY"
    awsSecret := "SECRET"
    token := ""
    // set credentials
    creds := credentials.NewStaticCredentials(awsAccessKey, awsSecret, token)
    credentials, err := creds.Get()
    if err != nil {
        fmt.Printf("bad credentials: %s", err)
    }
    fmt.Println(credentials)
    //setup config and s3 settings
    cfg := aws.NewConfig().WithRegion("ap-southeast-1").WithCredentials(creds)

    //create s3 credentail
    svc := s3.New(session.New(), cfg)
    type Sizer interface {
        Size() int64
    }

    size := file.(Sizer).Size()
    // create a buffer of size = images size
    buffer := make([]byte, size)
    file.Read(buffer)
    fileBytes := bytes.NewReader(buffer)
    fileType := http.DetectContentType(buffer)

    path := "mybucketname/" + filename
    params := &s3.PutObjectInput{
        Bucket:        aws.String("mybucketname"),
        Key:           aws.String(path),
        Body:          fileBytes,
        ContentLength: aws.Int64(size),
        ContentType:   aws.String(fileType),
        ACL:           aws.String("public-read"),
    }
    resp, err := svc.PutObject(params)
    if err != nil {
        fmt.Printf("bad response: %s", err)
    }
    fmt.Printf("response %s", awsutil.StringValue(resp))

    Response.Status = "success"
    Response.Filename = awsutil.StringValue(resp)

}

defer file.Close()
res.Header().Set("Content-Type", "application/json")
rnd.JSON(res, http.StatusOK, Response)
}

This function returns the status as success on successful upload of the image and the file name as http response.

In console I can see some response as :

response {
ETag: "\"bd9be6ada974e66a154552edc78b4a81\""
}

I've no clue on what ETag means, but I understood that the image is uploaded and I got some positive response from s3. But I'm unable to find the image that I've uploaded in s3.

I need some help to solve this. Thanks in advance.

Check result.Location.

Start with the documentation @ https://docs.aws.amazon.com/sdk-for-go/api/service/s3/ and change it line by line until you get what you want.

You can retrieve the uploaded s3 object like this:

svc := s3.New(session.New(), cfg)

path := "mybucketname/" + filename
input := &s3.GetObjectInput{
    Bucket: aws.String("mybucketname"),
    Key:    aws.String(path),
}

result, err := svc.GetObject(input)
if err != nil {
    if aerr, ok := err.(awserr.Error); ok {
        switch aerr.Code() {
        case s3.ErrCodeNoSuchKey:
            fmt.Println(s3.ErrCodeNoSuchKey, aerr.Error())
        default:
            fmt.Println(aerr.Error())
        }
    } else {
        // Print the error, cast err to awserr.Error to get the Code and
        // Message from an error.
        fmt.Println(err.Error())
    }
    return
}

fmt.Println(result)

Shameless plug: You can also use the command line tool I created from the below link to view the object.

https://github.com/bharath-srinivas/nephele

You just have to do:

$ nephele s3 list <bucket-name> --prefix <prefix of the key/filename>

You can refer to the official documentation of aws-sdk-go here: https://docs.aws.amazon.com/sdk-for-go/api/service/s3/#S3.GetObject