Rollup Development Server Plugin

Common errors

• Error: listen EADDRINUSE: address already in use :::10001

  cause The configured server port (e.g., 10001) is already being used by another application or a previous instance of your development server.
  fix Change the `port` option in your `server()` plugin configuration to an unused port number (e.g., 10002) or terminate the process currently occupying the port.

• ENOENT: no such file or directory, open 'path/to/server.key'

  cause The `ssl_key` or `ssl_cert` option in your server configuration points to a file that does not exist at the specified path.
  fix Verify that the paths provided to `fs.readFileSync()` for `ssl_key` and `ssl_cert` are correct and that the files exist relative to where your Rollup configuration is run.

• RollupError: Could not resolve entry.js

  cause Rollup cannot find the entry file specified in your `input` (or deprecated `entry`) configuration. This is often a pathing issue or the file doesn't exist.
  fix Ensure the `input` path in your Rollup configuration correctly points to an existing JavaScript entry file. Use `path.resolve(__dirname, 'your-entry.js')` for robustness.

Warnings

• gotcha The plugin is currently at version 0.7.0 and has not seen updates for several years. While functional, it might not be actively maintained, and future Rollup versions could introduce incompatibilities.
  Fix: Thoroughly test with your specific Rollup version and project setup. Consider forking or using a more actively maintained alternative if issues arise with newer Rollup versions.
• gotcha When using `ssl: true`, the `ssl_key` and `ssl_cert` options require the actual certificate and key content (e.g., read using `fs.readFileSync`), not just their file paths. Improperly formatted or invalid certificate data will cause the HTTPS server to fail.
  Fix: Ensure `ssl_key` and `ssl_cert` are correctly populated with the buffer contents of valid SSL/TLS certificates and private keys. Example: `ssl_key: fs.readFileSync('server.key')`.
• gotcha If the specified `port` (default 10001) is already in use by another process, the server will fail to start without a clear message in some environments. This can lead to silent failures or errors related to address binding.
  Fix: Choose a different `port` number if you encounter issues starting the server, or ensure no other applications are using the default port. On Linux/macOS, `lsof -i :<port>` can identify processes using a port.
• deprecated The README and examples show `entry` and `dest` options in the Rollup config. These options are deprecated in modern Rollup versions (>=1.0) in favor of `input` and `output.file` or `output.dir`.
  Fix: Update your Rollup configuration to use `input` for the entry point and `output.file` (for single bundles) or `output.dir` (for code splitting) for the output destination, as shown in the quickstart example.

Install

• npm install rollup-plugin-server npm
• yarn add rollup-plugin-server yarn
• pnpm add rollup-plugin-server pnpm

Imports

• server
  wrong:

  const server = require('rollup-plugin-server')

  correct:

  import server from 'rollup-plugin-server'

  The plugin is primarily consumed in ESM `rollup.config.js` files. While CommonJS `require` might work in some older Node environments, `import` is the idiomatic way for Rollup configurations.
• server
  wrong:

  server({ contentBase: ['dist'], open: 'true' })

  correct:

  server({ open: true, contentBase: 'dist' })

  The plugin's default export is a function that takes either a string for `contentBase` or an options object. Boolean options like `open` should be actual booleans, not strings.
• ssl_key
  wrong:

  ssl_key: 'server.key'

  correct:

  import fs from 'fs'; /* ... */ ssl_key: fs.readFileSync('server.key')

  For HTTPS, `ssl_key` and `ssl_cert` expect buffer content read from files (e.g., using Node's `fs.readFileSync`), not just file paths. The `fs` module is a Node.js built-in.

Quickstart

This quickstart demonstrates configuring `rollup-plugin-server` to serve a basic Rollup bundle from a 'dist' directory, automatically opening the browser to `http://localhost:10001`.

import server from 'rollup-plugin-server';
import path from 'path';
import fs from 'fs';

// Create a dummy entry file for Rollup to process
const entryFilePath = path.resolve(__dirname, 'entry.js');
fs.writeFileSync(entryFilePath, 'console.log("Hello from Rollup bundle!");');

// Create a dummy dist directory and an index.html
const distDirPath = path.resolve(__dirname, 'dist');
if (!fs.existsSync(distDirPath)) {
  fs.mkdirSync(distDirPath);
}
const indexHtmlPath = path.join(distDirPath, 'index.html');
fs.writeFileSync(indexHtmlPath, '<!DOCTYPE html>\n<html><head><title>Rollup App</title></head><body><div id="app"></div><script src="bundle.js"></script></body></html>');

export default {
  input: entryFilePath,
  output: {
    file: path.join(distDirPath, 'bundle.js'),
    format: 'esm'
  },
  plugins: [
    server({
      open: true, // Automatically open the browser
      verbose: true, // Show server address in console
      contentBase: distDirPath, // Serve files from the 'dist' directory
      host: 'localhost',
      port: 10001,
      historyApiFallback: true // Serve index.html for 404s
    })
  ]
};