featuretoggle-client-node

A node client to retrieve feature toggles stored in Etcd.

Installation

npm install featuretoggle-client-node

Usage

var Client = require('featuretoggle-client-node');

var client = new Client("application-name", {
    etcdHost: "127.0.0.1",
    etcdPort: 4001,
    cacheIntervalMs: 60000
});

client.on("error", function(err) {
    console.log(err);
});

client.on("initialized", function() {
    
    client.get("toggle1", function(err, value) {
        console.log(value);
    });
    
    client.getOrDefault("toggle2", true, function(err, value) {
        console.log(value);
    });

});

Important Note

The "error" event must be subscribed to, otherwise errors will cause the application to exit

client.on("error", function(err) { });

Etcd

Feature toggles are stored in Etcd using the following convention: http://host:port/v2/keys/v1/toggles/applicationName/toggleName

API

Client(applicationName, [config])

Creates a new feature toggle client

var Client = require("featuretoggle-client-node");
var client = new Client("application-name", { etcdHost: "127.0.0.1" });

• applicationName the name of the application used to find feature toggles
• config (optional)
  • etcdHost (default: "127.0.0.1")
  • etcdPort (default: 4001)
  • cacheIntervalMs interval for the cache update, which loads all the applications toggles into memory (default: 60000)

.on(eventName, callback)

Subscribs to events emitted by the client.

• error [required]
• initialized
• updating-cache
• updated-cache

.get(toggleName, callback)

Gets the value of a feature toggle (true or false) if exists, otherwise return null

• toggleName the name of the toggle, used with the application name to get the feature toggle value
• callback function with parameters (err, value)

.getOrDefault(toggleName, defaultValue, callback)

Gets the value of a feature toggle (true or false) if exists, otherwise return the default value (true or false)

• toggleName the name of the toggle, used with the application name to get the feature toggle value
• defaultValue the value to return if the toggle value is not found or if there is an error
• callback function with parameters (err, value)