Simple server and client config module. Originally written for wp-calypso.


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20Mar 16, 2018Mar 13, 2018Minified + gzip package size for @automattic/calypso-config in KB



This library can be used for managing server- and client-side configs.

All configs are stored in .json files (see examples in sample-config) in a config folder in your working directory. This path can be overridden via the CALYPSO_CONFIG_PATH environment variable.

At boot-up time, the server decides which config file to use based on the NODE_ENV environment variable. The default value is development. For values shared across environments, add them to the _shared.json file. Local-only values can be added via a {environment}.local.json file (e.g. development.local.json).

The entire configuration is available on the server-side and certain keys can be exposed to the client.

Server-side Usage

Config values can be retrieved by invoking the config() exported function with the desired key name:

import config from '@automattic/calypso-config';
console.log( config( 'redirect_uri' ) );

Client-side Usage

To access config values on the client-side, add the property name to the client.json file, which is a whitelist of config properties that will be exposed to the client.

A global configData object must also be output during the initial render. Here's an example using webpack and the interpolate

In your webpack build config:

const HtmlWebpackPlugin = require( 'html-webpack-plugin' );
const InterpolateHtmlPlugin = require( 'react-dev-utils/InterpolateHtmlPlugin' );

const clientData = require( '@automattic/calypso-config' ).clientData;

// ...

const interpolateHtmlData = Object.assign( {}, {
    CALYPSO_CONFIG_DATA_AS_JSON: JSON.stringify( clientData ),
} );

// ...

module.exports = {
    // ...

    plugins: [
        new InterpolateHtmlPlugin( interpolateHtmlData ),

        new HtmlWebpackPlugin( {
            inject: true,
            template: '/path/to/index.html',
        } ),

    // ...

Then, in your index.html template:

  <script>var configData = %CALYPSO_CONFIG_DATA_AS_JSON%;</script>

And finally, to access the configs:

import config from '@automattic/calypso-config/client';

console.log( config( 'redirect_uri' ) );
console.log( config.isEnabled( 'secret-features' ) );

Feature Flags

The config files contain a features object that can be used to determine whether to enable a feature for certain environments. This allows us to merge in-progress features without launching them to production. The config module adds a method to detect this: config.isEnabled(). Please make sure to add new feature flags alphabetically so they are easy to find.

    "features": {
        "manage/posts": true,
        "reader": true

Testing Feature Flags Locally

If you want to temporarily enable/disable some feature flags for a given build, you can do so by setting the ENABLE_FEATURES and/or DISABLE_FEATURES environment variables. Set them to a comma separated list of features you want to enable/disable, respectively:

ENABLE_FEATURES=manage/plugins/compatibility-warning DISABLE_FEATURES=code-splitting,reader npm start

Testing Feature Flags via URLs

If you want to temporarily enable/disable some feature flags you can add a ?flags= query parameter to the URL.

Note that this only works on development, staging, and calypso.live, not in production (this functionality is not suitable for public use on *.wordpress.com).

  • ?flags=foo enables feature foo.
  • ?flags=-bar disables feature bar.
  • ?flags=foo,-bar enables feature foo and disables feature bar.

E.g. http://calypso.localhost:3000/?flags=manage/plugins/compatibility-warning

If you find any bugs or have a feature request, please open an issue on github!

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