Environment specific configurations with Gulp for Angular JS (but any old js framework can use this)

README.md

To use this task, export MYAPP_ENV=development and call gulp env

development.json

{
  "name": "myApp"
  "api_url": "/api/v1",
  "cache": true,
  "http_headers": {
    "Authorization": "Bearer 8675309"
  }
}

environments.ejs

angular.module('<%= name %>', []).constant("AppConfig", {
  "api_url": "<%= api_url %>",
  "cache": <%= cache %>,
  "http_headers": <%= JSON.stringify(http_headers) %>
});

gulpfile.js

'use strict';

var gulp = require('gulp'),
    rename = require('gulp-rename'),
    path = require('path'),
    template = require('gulp-template');
    
var ENV = process.env.MYAPP_ENV ||  "development";
var config = require(path.join(__dirname, "config", "environments", ENV+".json"));

gulp.task('env', function () {
  return gulp.src('config/environments.ejs')
      .pipe(template(config))
      .pipe(rename({basename: 'config', extname: '.js'}))
      .pipe(gulp.dest('app/components'));
});