Hobknob

The simple, distributed feature toggle framework

Ryan Tomlinson / @ryantomlinson

History

• Built in my 20% time
• Made it easy to adopt
• 23 teams adopted it. Hundreds of toggles. 0 downtime

Why feature toggling?

• Particularly on a monolithic shared codebase
• Mean time to recovery. When issues occur, how quickly can we resolve theme. Can we turn off pieces off functionality?
• Etsy, flickr and google as examples. Turn off features that aren't core
• Doesn't mean everything is released instantly. Means it's releasable.

"Architecture"

• Notice no API. etcd solves that problem for us. That's why we chose it (amongst other reasons)

The Dashboard

Features

• Passport.js (could support many other auth mechanisms

DEMO: dashboard

• https://github.com/opentable/hobknob
• Installation - talk through
• Features - Authentication, auditing etc
• DEMO - creating a product
• DEMO - creating a toggle

The Clients

• Clients for .NET, Java, Node.js, Go
• Fault tolerant
• Simple

• Clients are fully OSS and on github
• Maintain a cache. If server/db goes down they maintain state.
• Won't deploy unless has initial state
• Single method

Client installation/usage

$ npm install hobknob-client-nodejs --save

var Client = require('hobknob-client-nodejs');

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

var isFeatureToggle1Enabled = client.getOrDefault('myFeatureToggle', false);

A bit about etcd

• Distributed key/value store
• RAFT - http://thesecretlivesofdata.com/raft/
• HTTP interface

$ curl -L http://127.0.0.1:2379/v2/keys/mykey -XPUT -d value="this is awesome"
$ curl -L http://127.0.0.1:2379/v2/keys/mykey

• http://127.0.0.1:2379/v2/keys/

Questions?