kibana/tasks/ui_framework.js

const sass = require('node-sass');
const postcss = require('postcss');
const postcssConfig = require('../src/optimize/postcss.config');
const chokidar = require('chokidar');
const debounce = require('lodash/function/debounce');
const platform = require('os').platform();

module.exports = function (grunt) {
  grunt.registerTask('uiFramework:start', function () {
    const done = this.async();
    Promise.all([uiFrameworkWatch(), uiFrameworkServerStart()]).then(done);
  });

  function uiFrameworkServerStart() {
    const serverCmd = {
      cmd: /^win/.test(platform) ? '.\\node_modules\\.bin\\webpack-dev-server.cmd' : './node_modules/.bin/webpack-dev-server',
      args: [
        '--config=ui_framework/doc_site/webpack.config.js',
        '--hot ',
        '--inline',
        '--content-base=ui_framework/doc_site/build',
        '--host=0.0.0.0',
        '--port=8020',
      ],
      opts: { stdio: 'inherit' }
    };

    return new Promise((resolve, reject) => {
      grunt.util.spawn(serverCmd, (error, result, code) => {
        if (error || code !== 0) {
          const message = result.stderr || result.stdout;

          grunt.log.error(message);

          return reject();
        }

        grunt.log.writeln(result);

        resolve();
      });

    });
  }

  function uiFrameworkCompile() {
    sass.render({
      file: 'ui_framework/components/index.scss'
    }, function (error, result) {
      if (error) {
        grunt.log.error(error);
      }

      postcss([postcssConfig])
        .process(result.css, { from: 'ui_framework/components/index.scss', to: 'ui_framework/dist/ui_framework.css' })
        .then(result => {
          grunt.file.write('ui_framework/dist/ui_framework.css', result.css);

          if (result.map) {
            grunt.file.write('ui_framework/dist/ui_framework.css.map', result.map);
          }
        });
    });
  }

  function uiFrameworkWatch() {
    const debouncedCompile = debounce(uiFrameworkCompile, 400, { leading: true });

    return new Promise((resolve, reject) => {
      debouncedCompile();

      chokidar.watch('ui_framework/components', { ignoreInitial: true }).on('all', (event, path) => {
        grunt.log.writeln(event, path);
        debouncedCompile();
      });
    });
  }
};