foo.js

    webpack_config.entry.unshift(
        'webpack-dev-server/client?' + argv.root_url,
        'webpack/hot/dev-server'
    );
    webpack_config.plugins.unshift(
        new webpack.HotModuleReplacementPlugin()
    );
    webpack_config.devtool = '#source-map';
    webpack_config.pathInfo = true;

    return Promise.promisifyAll(new WebpackDevServer(webpack(webpack_config), {
        contentBase: argv.static_compiled,
        inline: true,
        hot: true,
        stats: {colors: true}
    })).listenAsync(argv.port, argv.host).then(function () {
        gutil.log('[webpack-dev-server]', 'Listening on: ' + argv.root_url);
    }, function (err) {
        throw new gutil.PluginError('webpack-dev-server', err);
    });