Iterating over directories with Gulp?

You could use glob to get a list of directories and iterate over them, using gulp.src to create a separate pipeline for each feature. You can then return a promise which is resolved when all of your streams have ended.

var fs = require('fs');
var Q = require('q');
var gulp = require('gulp');
var glob = require('glob');

gulp.task('minify-features', function() {
  var promises = [];

  glob.sync('/js/features/*').forEach(function(filePath) {
    if (fs.statSync(filePath).isDirectory()) {
      var defer = Q.defer();
      var pipeline = gulp.src(filePath + '/**/*.js')
        .pipe(uglify())
        .pipe(concat(path.basename(filePath) + '.min.js'))
        .pipe(gulp.dest(filePath));
      pipeline.on('end', function() {
        defer.resolve();
      });
      promises.push(defer.promise);
    }
  });

  return Q.all(promises);
});

There's an official recipe for this: Generating a file per folder

var fs = require('fs');
var path = require('path');
var merge = require('merge-stream');
var gulp = require('gulp');
var concat = require('gulp-concat');
var rename = require('gulp-rename');
var uglify = require('gulp-uglify');

var scriptsPath = 'src/scripts';

function getFolders(dir) {
    return fs.readdirSync(dir)
      .filter(function(file) {
        return fs.statSync(path.join(dir, file)).isDirectory();
      });
}

gulp.task('scripts', function() {
   var folders = getFolders(scriptsPath);

   var tasks = folders.map(function(folder) {
      return gulp.src(path.join(scriptsPath, folder, '/**/*.js'))
        // concat into foldername.js
        .pipe(concat(folder + '.js'))
        // write to output
        .pipe(gulp.dest(scriptsPath)) 
        // minify
        .pipe(uglify())    
        // rename to folder.min.js
        .pipe(rename(folder + '.min.js')) 
        // write to output again
        .pipe(gulp.dest(scriptsPath));    
   });

   // process all remaining files in scriptsPath root into main.js and main.min.js files
   var root = gulp.src(path.join(scriptsPath, '/*.js'))
        .pipe(concat('main.js'))
        .pipe(gulp.dest(scriptsPath))
        .pipe(uglify())
        .pipe(rename('main.min.js'))
        .pipe(gulp.dest(scriptsPath));

   return merge(tasks, root);
});