If you haven't used Grunt before, be sure to check out the Getting Started guide, as it explains how to create a Gruntfile as well as install and use Grunt plugins. Once you're familiar with that process, you may install this plugin with this command:

npm install grunt-envpreprocess --save-dev

Once the plugin has been installed, it may be enabled inside your Gruntfile with this line of JavaScript:

grunt.loadNpmTask('grunt-envpreprocess');

The grunt-envpreprocess task

Text search and replacement in files is powered by the core of grunt-text-replace.

Overview

In your project's Gruntfile, add a section named envpreprocess to the data object passed into grunt.initConfig().

grunt.initConfig({
   envpreprocess:{
        dev:{
            files:{
                src:  'config/env.json'
            },
            options:{
                replacePath: ['dev_build/**/*.*'],
                environment: 'dev'
            }
        },
        prod:{
            files:{
                src:  'config/env.json'
            },
            options:{
                replacePath: ['dist_build/**/*.*'],
                environment: 'prod'
            }
        }
    }
});

(note that if you don't specify dev.options.environment, it will use the target, which in that case is dev)

When the task is run, you'll see a log output like this

Running "envpreprocess:prod" (envpreprocess) task
Reading ENV variables from config/env.json
Replaced all ENV variables in prod_build/**/*.*

Options

options.replacePath

Type: String

The path of files to have ENV variables replaced with the preprocessor.

options.environment

Type: String Default value: dev

Which environment to use when retrieving ENV variables from the .json file. If given "*", any environment that isn't specified will use that value.

Example Usage

Environment variables are defined in the config file located at the specified 'files.src' file. For each variable you must define a value for each environment, or use "*" to apply it to any environments that don't have a value specified. This is an example of such file

{
	"APP_NAME": {
		"dev": "AppDev",
		"prod": "AppProd"
	},
	"APP_VERSION": {
		"*": "0.1.0"
	},
	"API_BASE": {
		"dev": "http://localhost:8000",
		"prod": "https://www.mysite.com/api"
	}
}

Then in a file you want an ENV variable to be replaced, use something like this

    <head>
        <title>ENV.APP_NAME</title>
    </head>
    <script src="ENV.API_BASE/user/create">

    var version = "ENV.APP_VERSION";
    alert(version);

If you run 'grunt envpreprocess' with options.environment="dev", it will produce

    <head>
        <title>AppDev</title>
    </head>
    <script src="http://localhost:8000/user/create">

    var version = "0.1.0";
    alert(version);

Similarly, if you run 'grunt envpreprocess' with options.environment="prod", it will produce

    <head>
        <title>AppProd</title>
    </head>
    <script src="https://www.mysite.com/api/user/create">

    var version = "0.1.0";
    alert(version);

Demo

You can run a simple demo by cloning this repo and running grunt. In the demo/ directory there is test.html and demo/config/env.json to demonstrate how to define environment variables and use them in HTML/JS. To run the demo, run npm install && npm run demo. This will copy test.html to demo/build_output/ and then envpreprocess will be run to replace the environment variables inside the build output file.

Note that this is going to modify the files that you point it to. This means that you shouldn't point this task at your actual source files, but at a separate build folder containing a copy of the source.

Release History

0.1.0 - Initial release. Functionality is working. Not tested.

0.1.1 - added demo

0.1.2 - accepted PR from nicolasbd to use target as environment if not specified in options

0.1.3 - fix README format

Keywords

gruntplugin

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Package last updated on 24 May 2016

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