ycb

Yahoo! Configuration Bundle

YCB is a multi-dimensional configuration library that builds bundles from resource files describing a variety of values. The library allows applications to configure themselves based on multiple dimensions describing locations, languages, environments, etc.

Install

npm install ycb --save

Usage

var YCB = require('ycb');
var configArray = [
    {
        dimensions: [
            {
                environment: {
                    dev: null,
                    staging: null,
                    test: null,
                    prod: null
                },
            },
            {
                device: {
                    desktop: null,
                    mobile: {
                        tablet: null,
                        smartphone: null
                    }
                }
            }
        ]
    },
    {
        settings: ["master"],
        host: "example.com",
        prefix: null
    },
    {
        settings: ["environment:dev"],
        host: "dev.example.com"
    },
    {
        settings: ["environment:staging,test"],
        host: "stage.example.com"
    },
    {
        settings: ["device:smartphone"],
        prefix: 'm.'
    }
];

var ycbObj = new YCB.Ycb(configArray);
var computedConfig = ycbObj.read({ environment: 'dev' });

console.log(computedConfig.host); // dev.example.com

Scheduling Changes

We can schedule configuration changes ahead of time by defining an interval along with a config and using the time aware read method. For example the following program

var YCB = require('ycb');
var configArray = [
    {
        dimensions: [
            {
                environment: {
                    dev: null,
                    staging: null,
                    test: null,
                    prod: null
                },
            },
            {
                region: {
                    us: null,
                    ca: null
                }
            }
        ]
    },
    {
        settings: ["master"],
        host: "example.com"
    },
    {
        settings: {
            dimensions: ["region:us"]
        },
        logo: "logo.png"
    },
    {
        settings: {
            dimensions: ["region:us"],
            schedule: {
                start: "2019-11-28T00:04:00Z",
                end: "2019-11-29T00:04:00Z"
            }
        },
        logo: "thanksgiving-logo.png"
    }
];

var ycbObj = new YCB.Ycb(configArray, {cacheInfo:true});
var config1 = ycbObj.readTimeAware({region:'us'}, 0);
var config2 = ycbObj.readTimeAware({region:'us'}, 1574899440000);
var config3 = ycbObj.readTimeAware({region:'us'}, 1574985840001);
console.log(config1);
console.log(config2);
console.log(config3);

will print

{ host: 'example.com',
  logo: 'logo.png',
  __ycb_expires_at__: 1574899440000 }
{ host: 'example.com',
  logo: 'thanksgiving-logo.png',
  __ycb_expires_at__: 1574985840001 }
{ host: 'example.com', logo: 'logo.png' }

These intervals are closed and either start or end may be omitted to define a one sided interval.

To support proper cache expiration one may set the cacheInfo option, in which case the next time the config will change is added to the returned object.

Examples

Examples are provided in the tests directory.

License

BSD see LICENSE.txt