问Docker映像生成失败，“复制失败:未指定源文件”

EN

 package main
 import (
  "archive/tar"
  "bytes"
  "context"
  "fmt"
  "io"
  "io/ioutil"
  "os"

  "github.com/docker/docker/api/types"
  "github.com/docker/docker/client"
 )

func buildImage(client *client.Client, tags []string, dockerfile string) error {
ctx := context.Background()

// Create a buffer
buf := new(bytes.Buffer)
tw := tar.NewWriter(buf)
defer tw.Close()

// Create a filereader
dockerFileReader, err := os.Open(dockerfile)
if err != nil {
    return err
}

// Read the actual Dockerfile
readDockerFile, err := ioutil.ReadAll(dockerFileReader)
if err != nil {
    return err
}

// Make a TAR header for the file
tarHeader := &tar.Header{
    Name: dockerfile,
    Size: int64(len(readDockerFile)),
}

// Writes the header described for the TAR file
err = tw.WriteHeader(tarHeader)
if err != nil {
    return err
}

// Writes the dockerfile data to the TAR file
_, err = tw.Write(readDockerFile)
if err != nil {
    return err
}

dockerFileTarReader := bytes.NewReader(buf.Bytes())

buildOptions := types.ImageBuildOptions{
    Context:    dockerFileTarReader, 
    Dockerfile: dockerfile,
    Remove:     true,
    Tags:       tags,
}
// Build the actual image
imageBuildResponse, err := client.ImageBuild(
    ctx,
    dockerFileTarReader,
    buildOptions,
)

if err != nil {
    return err
}

// Read the STDOUT from the build process
defer imageBuildResponse.Body.Close()
_, err = io.Copy(os.Stdout, imageBuildResponse.Body)
if err != nil {
    return err
}

return nil
}

-- root
   |-- src 
       |--Dockerfile
       |--files
   |-- go-code
       |--build.go

FROM node:12


WORKDIR /app
COPY package*.json ./
RUN npm install

COPY . .

EXPOSE 3000

CMD [ "node", "index.js" ]

{"errorDetail":{"message":"COPY failed: no source files were specified"},"error":"COPY failed: no source files were specified"}