webpack.config.js

const defaultConfig = require( '@wordpress/scripts/config/webpack.config' );
const { resolve } = require( 'path' );
const { spawn } = require( 'child_process' );
const chalk = require( 'chalk' );

let rsyncError = false;

module.exports = {
	...defaultConfig,
	plugins: [
		...defaultConfig.plugins,
		/**
		 * During watch mode we want to sync the build directory to the server.
		 * This relies on the user setting the RSYNC_DESTINATION environment variable.
		 * If it doesn't exist then we don't do anything.
		 */
		process.env.RSYNC_DESTINATION && rsyncError === false
			? {
					apply: ( compiler ) => {
						compiler.hooks.done.tap(
							'CustomWatchClosePlugin',
							( stats ) => {
								if (
									! stats.hasErrors() &&
									! stats.hasWarnings() &&
									stats.compilation.compiler.watchMode
								) {
									process.stdout.write(
										'!!! --- UPLOADING TO SERVER --- !!!\n'
									);

									const rsync = spawn( 'rsync', [
										'-avz',
										resolve( '.', 'build' ),
										process.env.RSYNC_DESTINATION,
									] );

									/**
									 * Handle rsync output
									 *
									 * strip everything except the sent bytes
									 */
									rsync.stdout.on( 'data', ( data ) => {
										if (
											data.toString().includes( 'sent' )
										) {
											process.stdout.write(
												data.toString()
											);
										}
									} );

									/**
									 * Handle rsync errors
									 *
									 * If we have any errors we set the rsyncError flag to true
									 */
									rsync.stderr.on( 'data', ( data ) => {
										process.stderr.write(
											chalk.red(
												`rsync stderr: ${ data }`
											)
										);

										rsyncError = true;
									} );

									/**
									 * Handle rsync completion
									 */
									rsync.on( 'close', ( code ) => {
										if ( code === 0 ) {
											process.stdout.write(
												chalk.green(
													'!!! --- UPLOAD SUCCESS --- !!!\n'
												)
											);
										} else {
											process.stdout.write(
												chalk.red(
													`rsync process exited with code ${ code }`
												)
											);
										}
									} );
								}
							}
						);
					},
			  }
			: undefined,
	],
};