Creating Authentication Parameters for a Browser-based Upload (SDK for Go)

package main
import (
    "fmt"
    "os"
    obs "github.com/huaweicloud/huaweicloud-sdk-go-obs/obs"
)
func main() {
    //Obtain an AK/SK pair using environment variables or import an AK/SK pair in other ways. Using hard coding may result in leakage.
    //Obtain an AK/SK pair on the management console. For details, see https://support.huaweicloud.com/eu/usermanual-ca/ca_01_0003.html.
    ak := os.Getenv("AccessKeyID")
    sk := os.Getenv("SecretAccessKey")
    // (Optional) If you use a temporary AK/SK pair and a security token to access OBS, you are advised not to use hard coding to reduce leakage risks. You can obtain an AK/SK pair using environment variables or import an AK/SK pair in other ways.
    // securityToken := os.Getenv("SecurityToken")
    // Enter the endpoint corresponding to the bucket. EU-Dublin is used here as an example. Replace it with the one currently in use.
    endPoint := "https://obs.eu-west-101.myhuaweicloud.eu" 
    // Create an obsClient instance.
    // If you use a temporary AK/SK pair and a security token to access OBS, use the obs.WithSecurityToken method to specify a security token when creating an instance.
    obsClient, err := obs.New(ak, sk, endPoint/*, obs.WithSecurityToken(securityToken)*/)
    if err != nil {
        fmt.Printf("Create obsClient error, errMsg: %s", err.Error())
    }
    // Create a signed URL for uploading an object.
    input := &obs.CreateBrowserBasedSignatureInput{}
    input.Bucket = "examplebucket"
    input.Key = "example/objectname"
    input.FormParams = map[string]string{
        "content-type": "text/plain",
        "success_action_redirect": "https://www.example.com",
    }
    output, err := obsClient.CreateBrowserBasedSignature(input)
if err == nil {
        fmt.Printf("Policy:%s\n", output.Policy)
        fmt.Printf("Signature:%s\n", output.Signature)
    } else {
        fmt.Println(err)
        return
    }
    requestBody := &bytes.Buffer{}
    writer := multipart.NewWriter(requestBody)
    writer.WriteField("key", input.Key)
    writer.WriteField("AccessKeyId", ak)
    writer.WriteField("policy", output.Policy)
    writer.WriteField("signature", output.Signature)
    writer.WriteField("success_action_redirect", "https://www.example.com")
    // writer.WriteField("token", obs.WithSecurityToken(securityToken))
    writer.WriteField("Content-Type", "text/plain")
    formFile, _ := writer.CreateFormFile("file", "filename")
    io.Copy(formFile, strings.NewReader("hello OBS!"))
    writer.Close()
    url := "https://" + input.Bucket + "." + strings.Replace(endPoint, "https://", "", 1)
    request, err := http.NewRequest("POST", url, requestBody)
    if err != nil {
        fmt.Println(err)
        return
    }
    request.Header.Set("Content-Type", writer.FormDataContentType())
    client := &http.Client{}
    response, err := client.Do(request)
    if err != nil {
        fmt.Println(err)
        return
    }
    defer response.Body.Close()
    if err == nil {
        fmt.Printf("Use signed-url successful!\n")
        fmt.Printf("Status:%s,Etag:%s\n", response.Status, response.Header.Get("Etag"))
        return
    }
    fmt.Printf("Use signed-url successful!\n")
    fmt.Println("An Exception was found, which means the client encountered an internal problem when attempting to communicate with OBS, for example, the client was unable to access the network.")
    fmt.Println(err)
}