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Webpack plugin for automatically starting a node server from memory after building.


Version published
Yearly downloads
decreased by-28.61%

Weekly downloads



6.2.1 (2022-04-05)

Bug Fixes

  • issue with webpack double executing reload and ensure child process always killed (aa7e983)



Spawn Server (Webpack Plugin)

Webpack plugin for Node builds that will automatically load the build into memory when watching and restart the server on consecutive builds.



npm install spawn-server-webpack-plugin

webpack-dev-server version

webpack-dev-server >= 4 requires v6 of this module. webpack-dev-server <= 3 requires v5 of this module.

Example Config

const webpack = require("webpack"); const SpawnServerPlugin = require("spawn-server-webpack-plugin"); const spawnedServer = new SpawnServerPlugin({ args: [ "--inspect-brk", "-r", "some-file.js" ] }); // Build webpack config. const config = { target: "node", externals: [/^[^./!]/], // Trick to exclude node modules. entry: "./myfile.js", plugins: [ // Support inline sourcemaps. new webpack.BannerPlugin({ banner: 'require("source-map-support").install({ hookRequire: true })', raw: true }), // Use the plugin. spawnedServer ], output: { libraryTarget: "commonjs2", path: "dist" } }; // Start webpack and trigger watch mode. webpack(config).watch({ ignore: /node_modules/ }, (err, stats) => { // The built node server will start running in the background. }); // Special events (listening and closing) spawnedServer.on("listening", (address) => { this.address === { port: ..., ip: ... } this.listening === true }); spawnedServer.on("closing", () => { this.address === null this.listening === false });

Using with webpack-dev-server

To automatically proxy a WebpackDevServer to the active spawned server (and to ensure that requests wait during server rebuilds) you can add the config exposed under spawnedServerInstance.devServerConfig into your devServer webpack options.

const configs = [ {...}, // Browser build {...} // Server build (included spawn-server-plugin) ]; new DevServer(webpack(configs), { // Set your custom options, then spread in the spawned server config ...spawnedServer.devServerConfig }).listen(8081); // This is approximately the same as: new DevServer(webpack(configs), { ..., // Setup proxy to the actual server. proxy: { "**": { target: "http://localhost:8080" } }, // Ensure webpack waits for server build before reloading. setup (app) { app.use((req, res, next) => { if (spawnedServer.listening) next() else spawnedServer.once("listening", next) }) } }).listen(8081);

You can also add this configuration in the same way into the webpack.config.js file under the devServer option.

Multiple entry points

Often with server side bundling you will have a single entry point for your server (and thus webpack) which works perfectly with this plugin. If you need to use multiple entrypoints for your webpack config for the server then this plugin will look for an output file for the main entry. You can override this to use a different entry name via the mainEntry option to this plugin.

const spawnedServer = new SpawnServerPlugin({ mainEntry: "index" }); module.exports = { ..., entry: { index: "./src/index", other: "./src/other" }, ..., plugins: [ spawnedServer ] };

Dynamic Server Port

Using the devServerConfig will automatically set process.env.PORT = 0. This allows for the spawned server to start on the next available port if you use this environment variable as the port option when listening.

Process with multiple servers

By default this plugin will wait for the first http server to be listening and make that information available as the address. You can optionally provide a waitForAppReady: true option when instanciating the plugin and use process.send({ event: "app-ready", address: server.address() }) within your process to signal which server should be referenced.


  • Use npm test to run tests.

Please feel free to create a PR!



What is spawn-server-webpack-plugin?

Webpack plugin for automatically starting a node server from memory after building.

Is spawn-server-webpack-plugin popular?

The npm package spawn-server-webpack-plugin receives a total of 707 weekly downloads. As such, spawn-server-webpack-plugin popularity was classified as not popular.

Is spawn-server-webpack-plugin well maintained?

We found that spawn-server-webpack-plugin demonstrated a healthy version release cadence and project activity. It has 1 open source maintainer collaborating on the project.

Last updated on 05 Apr 2022


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