Features flags at BlaBlaCar

ParisWeb 2016 - Feature flags @ BlaBlaCar @odolbeau & @genes0r
Benjamin de Bernardi & Olivier Dolbeau Benjamin de Bernardi & Olivier Dolbeau Feature Flags at

Benjamin De Bernardi Lead Engineer Since 2014 @genes0r

Olivier Dolbeau Web architect Since 2012 @odolbeau

100€ 25€ 25€ 25€ 100€ 25€

15M 20M 10M 5M 1M 2015 2014 2013 2012 2011 2010 2009 25M members worldwide Over 35 million members and growing 1.5 million+ joining each month 35M 2016

Agenda • Past ◦ BlaBlaTech ◦ Fail Learn Succeed • Now ◦ Why feature flags rocks? ◦ What about the implementation? • Future

1

Features & people 100+ people in the tech team. • Code • Test • Deliver (fast) AT THE SAME TIME!

Angry developer

Angry Product owner

Medias

Angry ops

Deploying big features is too risky. It can’t be done for everyone at the same time anymore.

Testing a feature with 25M users is not a solution. We need to be able to test a feature only in a country or for some users.

The “Capital effect” must not happen anymore. We need to find a solution to maintain the website up even when the traffic is high.

Feature flags Feature flags Feature flags Feature flags Feature flags

A 'Feature Flag' (or Feature Toggle) is the ability to turn features (sub-sections) of your application on/off at a moments notice. Wikipedia

2

Tech & product guys are happy!

Activate a feature

Slowly rollout a new feature

Angry ops.

Deactivate a feature in production

Implementation

Device agnostic

No deployment

What do we need? • a storage to store all feature flags and their rules • an admin interface to create / update / delete feature flags • a PHP library to use in our application

Existing solutions • etsy / features • joshuaestes / feature-toggle • opensoft / rollout • qandidate / toggle

Existing solutions • etsy / features • joshuaestes / feature-toggle • opensoft / rollout • qandidate / toggle deprecated

Existing solutions • etsy / features • joshuaestes / feature-toggle • opensoft / rollout • qandidate / toggle deprecated no storage logic

Existing solutions • etsy / features • joshuaestes / feature-toggle • opensoft / rollout • qandidate / toggle deprecated no storage logic Good choice!

Existing solutions • etsy / features • joshuaestes / feature-toggle • opensoft / rollout • qandidate / toggle deprecated no storage logic Good choice! Even better!

http://labs.qandidate.com/blog/2014/08/18 /a-new-feature-toggling-library-for-php/

Meet Qandidate\Toggle

Checking values: operators

Context

Putting it all together

http://labs.qandidate.com/blog/2014/08/19/ open-sourcing-our-feature-toggle-api-and-ui/ API UI

How it works for us?

What will we explain? Storages Strategies Operators & Context Devices Administration

Storages

Storages APCu Our own implementations.

• Primary data store • 1 key containing all toggles • 1 key / toggle containing its configuration (encoded JSON)

• Cache layer (60 seconds) • Encapsulation FTW • Encoded JSON APCu

Strategies

Operators

>= >= LessThan LessThanEqual MatchesRegex Percentage Available operators EqualsTo GreaterThan GreaterThanEqual InSet = [...] < %% % >

Implementation

Implementation - Context

Implementation - Context Mainly focused on the user.

Implementation - Context Can be website centric.

Can also be feature centric. Implementation - Context

Implementation - Manager

Implementation - Views

Devices Devices

Mobile apps API Flags Native flags

Internal Flags Export JSON Get JSON

Internal Flags

Name Internal Flags

Strategy Internal Flags

Conditions Internal Flags

Context key Internal Flags

Flaggr Open Source Android : blablacar/flaggr-android iOS : blablacar/flaggr-ios (soon)

We have 100+ toggles.

We can define toggles / devices

Name Strategy Conditions summary Actions

Basic settings 1. User id 2. Website locale 3. User percentage 4. User phone extension 5. Currency

Example

Rules 1. Displayed in France only a. Will be activated for other countries later (BE, PL, NL) 2. Two kinds of results a. Beginners only b. Cheapest rides 3. Only for logged users 4. Activate for 50% of the users to control the impact

Flag

Implementation

Geo based conditions • Axis between cities • GeoJSON inside ElasticSearch

Features activation & A/B test Partnership with on Paris - Lyon Partnership with on Paris - Nancy Geo based conditions

Internal A/B test tool.

Internal A/B test tool. Why ? • External tools are JavaScript based (GTM & Optimizely) • Upgrades upon need

Internal A/B test tool. New settings • User grade

Internal A/B test tool. New settings • Visitor group ◦ Cookie set by Nginx ◦ 18 groups

3

To improve • Feature flag removal • Deal with permissions - In progress • Use a flag for “old” features • Naming!

Feature flags?

Yes.

Questions?

Thank you BlaBlaCar is hiring !

Features flags at BlaBlaCar

Features flags at BlaBlaCar

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