properties-gen

CLI that generates properties files for a given environment.

Motivation

You need to build your application for different targets, so you have a base configuration file with default values and want to override specific ones for the rest of the targets.

This way you dont need to define every dynamic value by using environment variables.

Features

• extends from base file
• parse env variables
• output configuatio as JSON or JS files

Installation

Locally in your project.

$ npm install -D properties-gen

or globally

$ npm install -g properties-gen

Install with yarn

$ yarn i properties-gen --save-dev

command line options

Usage: properties-gen [options] [command]

Options:
  -h, --help          display help for command

Commands:
  init                Generates default config file
  generate [options]  Generates environment properties files
  help [command]      display help for command

Options for generate command:

Usage: properties-gen generate [options]

Generates environment properties files

Options:
  -f, --file [pathToFile]  Specify configuration file
  -h, --help               display help for command

Usage

Configuration

Generate the initial configuration file

$ npx properties-gen init

This will create a properties.config.json file in your root directory, notice you can define as many properties files as you need (groups in the configurationGroups array), usually we just need client, server or both.

{
  "configurationGroups": [
    {
      "inputFolder": "config/server/",
      "inputFileNamePattern": "env.{{envTargetKey}}.json",
      "outputFile": "environment/env.server.js",
      "extendsFromBase": true,
      "fileBaseName": "base.json"
    },
    {
      "inputFolder": "config/client/",
      "inputFileNamePattern": "env.{{envTargetKey}}.json",
      "outputFile": "environment/env.client.js",
      "extendsFromBase": true,
      "fileBaseName": "base.json"
    }
  ],
  "envTargetKey": "NODE_ENV",
  "defaultEnvTargetValue": "dev"
}

name	type	description
envTargetKey	{String}	default: NODE_ENV Environment variable key which dictates the environment file to process. (e.g.) COUNTRY, TENANT
defaultEnvTargetValue	{String}	default: dev Fallback value for envTargetKey key. (e.g. NODE_ENV=dev)
configurationGroups	Array of {configurationGroup}
configurationGroup.inputFolder	{String}	default: config/server/ Folder where configuration files are located
configurationGroup.inputFileNamePattern	{String}	default: env.{{envTargetKey}}.json The name pattern for the input files, notice you must include {{envTargetKey}} in order to dynamically pick the right one when running the generate command.
configurationGroup.outputFile	{String}	default: environment/env.groupName.js The output filename, only .json or .js extensions are valid.
configurationGroup.extendsFromBase	{Boolean}	default: true When active will look for a base.json file in the configurationGroup.inputFolder location in order to extend the configuration values.
configurationGroup.fileBaseName	{String}	default: base.json The base configuration file name to pick when configurationGroup.extendsFromBase is true, only .json or .js extensions are valid.

Define your configuration files

For each configuration group, create the folder that contains the base.json (if extendsFromBase is true) and as many env.{ENV}.json files as you need, for example:

config/server/base.json

{
  "isProduction": false,
  "someKey": "someValue",
  "msHost": "http://localhost:3010/",
  "db": {
    "someSecret": "{{SECRET}}"
  }
}

Overrite and extend values for the rest of environments.

config/server/env.dev.json

{
  "msHost": "http://api.dev.myapp.com"
}

config/server/env.prod.json

{
  "isProduction": true,
  "msHost": "https://api.myapp.com/"
}

Generate environment files

npx properties-gen generate

This command will take the current environment to generate the properties file in the location defined on outputFile. Notice NODE_ENV is the default key for the environments but you can override this value by setting a different one in envTargetKey like COUNTRY or TENANT.

Example:

NODE_ENV=prod SECRET=mySecret npx properties-gen generate

output: environment/env.server.js

module.exports = {
  isProduction: true,
  someKey: 'someValue',
  msHost: 'https://api.myapp.com/',
  db: {
    someSecret: 'mySecret',
  },
}

Tip: use npx properties-gen init to create the configuration file, then install properties-gen as a development dependency in your project and finally chain the properties-gen generate command before the start|dev|build command, so properties are generated before running the project.

Tip: you may want to add the output file to .gitignore as is not meant to be tracked

Package script example using NextJs

package.json

{
  "name": "myApp",
  "scripts": {
    "config": "properties-gen generate",
    "dev": "npm run config && next dev",
    "build": "npm run config && next build",
    "start": "next start"
  }
}