killswitch

Simple utility to help roll in new website features while providing a clearly defined backout "killswitch" mechanism.

Installation

After install node:

$ npm install killswitch

Usage

First create a json file that will define each of the killswitches in an application.

  {
    "newFeatureOne":{
      "enabled":true,
      "description":"Killswitch to control toggle between existing implementation and new Updated version",
      "targets":["feature-module", "another-module"],
      "startDate":"Jan 15, 2015",
      "endDate":"Feb 15, 2015"
      },
      "useSpriteImages":{
        "enabled":false,
        "description":"Implementation of sprites for thumbnails",
        "targets":["npm-thumbs"],
        "startDate":"Dec 1, 2014",
        "endDate":"Mar 10, 2015"
      }
  }

Each killswitch definition must have the following required properties enabled,description, targets as an array, startDate, endDate and the following option properties enabledValue and disabledValue. These optional values will be returned via the method getValue(key, info), this method will default to boolean true/false if either enabledValue and disabledValue are missing.

Next, consume in feature module and create condition check:

//in feature-module.js
var Killswitch = require("killswitch"),
    info = require("../package.json"),
    ks = new Killswitch();
module.exports.getJSON = function(){
  var oldFeatureData = { name:"John Doe", age:30, address:"100 Pine Street"};
  var newFeatureData = { name:"Jane Doe", age:30, address"100 Pine Street", layoutType:"basic", url:"www.thedoes.com", familyHistory:"coming soon"}
  
  //notice this killswitch 'newFeatureOne' does not have enabledValue or disabledValue
  //will default to true if enabled or false if disabled
  return ks.getBoolean("newFeatureOne", info) ? newFeatureData : oldFeatureData;

Alternatively if we did include an enabledValue/disabledValue we could have done something like:

"newFeatureOne":{
      "enabled":true,
      "description":"Killswitch to control toggle between existing implementation and new Updated version",
      "targets":["feature-module", "another-module"],
      "startDate":"Jan 15, 2015",
      "endDate":"Feb 15, 2015",
      "enabledValue":"newFeature",
      "disabledValue":"oldFeature"
}

and returned as:

  var obj = {};
  obj[ks.getValue("newFeatureOne", info)] = ks.getBoolean("newFeatureOne", info) ? newFeatureData : oldFeatureData;
  return obj;

Would produce:

{
  newFeature: { name:"Jane Doe", age:30, address"100 Pine Street", layoutType:"basic", url:"www.thedoes.com", familyHistory:"coming soon"}
}

Which would simplify our handlebars template changes to:

<div>
    {{#if newFeature}}
      {{> myNewPartial newFeature}}
    {{otherwise}}
      {{> currentPartial oldFeature}} 
    {{/if}}
</div>