Node.js 在Docker容器404页面中找不到服务器(提供静态reactjs文件)

我正在try 包装一个在端口8000上提供静态文件的Go应用程序.我看过关于这个话题的其他帖子，很多人似乎都说用router.Run("0.0.0.0:8000")或router.Run(":8000").我两个都试过了，但还是不成功.我的main.go如下所示:

package main

// required packages
import (

    "fmt"
    "log"
    "os"

    "github.com/gin-gonic/gin"
    "github.com/gin-contrib/cors
    "net/http"
)

func main() {
    // start the server
    serveApplication()

}

func serveApplication() {
    corsConfig := cors.Config {
        AllowOrigins: []string{"*"},
        AllowMethods: []string{"GET", "POST", "PUT", "DELETE", "OPTIONS"},
        AllowHeaders: []string{"Origin", "Content-Type", "Authorization"},
        AllowCredentials: true,
    }

    router := gin.Default()
    router.Use(cors.New(corsConfig))

    router.StaticFS("/static", http.Dir("./frontend/build/static"))
    router.StaticFile("/", "./frontend/build/index.html")
    router.Run(":8000")
    fmt.Println("Server running on port 8000")
}

和以下Dockerfile:

FROM node:16-alpine3.11 as build-node

WORKDIR /workdir
COPY frontend/ .
RUN yarn install
RUN yarn build

COPY .env /workdir/

FROM golang:1.21-rc-alpine3.18 as build-go
#FROM golang:1.17rc2-alpine3.14 as build-go

ENV GOPATH ""
RUN go env -w GOPROXY=direct
RUN apk add git

ADD go.mod go.sum ./
RUN go mod download
ADD . .
COPY --from=build-node /workdir/build ./frontend/build
RUN go build -o /main

FROM alpine:3.13
COPY --from=build-go /main /main
COPY --from=build-node /workdir/.env .env
EXPOSE 8000
ENTRYPOINT [ "/main" ]

我的文件夹 struct 如下所示；

portal
- frontend (here the react app is stored)
- backend (all my backend logic)
- Dockerfile
- main.go
- go.mod

当我在本地运行go run main.go时，前端在端口8000上被正确地服务，并且加载http://localhost:8000工作得很好.当我用docker build -t portal .构建docker映像，然后用docker run -p 8000:8000 --name portal portal运行它时，我可以在终端中看到服务器启动，并说它在端口8000上运行，但我总是得到404页未找到错误.

我试过用router.run("0.0.0.0:8000")、router.run("localhost:8000")或docker run --network host --name portal portal.

我有什么遗漏的吗？我是否将前端构建复制到了错误的位置？