I use tomcat as a backend server. The port is 8080. I don"t want to modify this. I want to modify the port of webpack Server.
I checked a lot on the Internet, all saying

devServer{
  host:....,
  port:....
}

but I tried but failed? Webpack is a novice. Boss, please give me some advice

the code is as follows:

var webpack=require("webpack");
const path=require("path");
//const htmlWebpackPlugin=require("html-webpack-plugin");
//const urlLoader=require("url-loader"); //base64
// path 
module.exports = {
    entry: "./src/main.js",
    //common.js 
    devServer: {
        host:"127.0.0.1",
        open:true,
        port:8090
    },
    output: {
        path: path.resolve(__dirname,"dist"),
        filename: "[name].bundle.js",
    },
    //
    devServer:{
        // webpack-dev-server
    },
    module: {
        rules: [
        //webpack 2.0 3.0 loaders
        //webpack 4.0 rules
        { 
            test: /\.css$/,
            use:[
            "style-loader",
            "css-loader",
             "less-loader",
             "postcss-loader"
            ]
        },{
                test: require.resolve("jquery"),
                use: [{
                    loader: "expose-loader",
                    options: "jQuery"
                },{
                    loader: "expose-loader",
                    options: "$"
                }]
        }, {
                test: /\.js$/,
                loader: "babel-loader",
                exclude: /node_modules/
            },{
                test: /\.(png|jpe?g|gif|svg)(\?.*)?$/,
                use:[
                    {
                        loader:"url-loader",
                        options:{
                            limit:1000,
                            name:"/static/images/assets/[hash:8].[name].[ext]"
                        }
                    }
                ]
            }
        
//            {test: /\.css$/, loader: "style-loader!css-loader",modules:true},
//          {test:/\.png$/,loader:"url-loader?limit=10000"}
        ]
    },
    mode: "development",
    
};