how to scale your app and win the cloud challenge

HOW TO SCALE YOUR APP AND WIN THE CLOUD CHALLENGEQUENTIN ADAM

@WAXZCE2013

Quentin ADAM

Clever Cloud CEO

@waxzce on twitter

http://www.waxzce.org

WHO I AM ?

Java, scala, python, nodejs, php… apps scaling automatically in the cloud.

We cover your ass, you can focus on your own stuff

http://www.clever-cloud.com

PAAS PROVIDER

WHEN YOU NEED TO SCALE

THERE ARE 2 WAYS

GROWING AND GROWING UNTIL YOU EXPLODE OR BECOME WEIRD

OR SPLIT THE WORK AND MAKE YOUR SOFTWARE WORK AS A TEAM

Build an army of fat app

YOU CAN DO BOTH

SO WE NEED TO BE ABLE TO DISPATCH THE WORK

SCALE OUT

• Many workers doing the same thing

• No SPOF

• Growing is more easy

• Introduce best practice

SCALE UP

• 1 Fat instance

• 1 Fat application

• SPOF (single point of failure)

• Hard to maintain

• Always has a limit

• Short term meaning

BEST LONG

TERM

SOLUTION

SO, HOW TO SCALE OUT ?JUST SOME FACTS

SPLIT PROCESS AND STORAGE

Storage• Databases• Files• Sessions• Events• …

Code• Can be replicated• Stateless• Process

Picking one instance or another doesn’t matter

STATELESSNESS IS THE KEY

CONSIDER MORE THINGS AS DATA• User account

• Users data

• Files

• Sessions

• Events

CHOOSE DATASTORE WISELYYOU CAN SHOULD USE MANY DATASTORES

DATASTORE CHOICES ARE DRIVEN BY USAGE

Make decisions based on

needs

Do I need atomicity of requests ?

Do I need concurrent access ?

Do I mostly read or write ?

Do I need relational ?

Do I need big storage capacity ?

Do I need high

availability ?

• Not a big volume

• DB have to manage data TTL

• Data model : K/V

• Multiple writes at the same time

• High availability

I need to store sessions

QUICK EXAMPLE

• Not a big volume It’s OK, PG can handle small quantity of data

• DB have to manage data TTL

No, I have to do it manually

• Data model : K/VNo, PG is relational (mainly)

• Multiple writes at the same time

No, PG is Atomic

• High availability

PG is awesome ;-) Use of PG bouncer or similar allow good clustering

I need to store sessions

QUICK EXAMPLE

• Not a big volume It’s OK, redis can handle small quantity of data

• DB have to manage data TTL

Yes Redis can do it

• Data model : K/V Yes

• Multiple writes at the same time

No, redis is pseudo Atomic (master/slave)

• High availabilityRedis is great, but cauterization is rude…

I need to store sessions

QUICK EXAMPLE

• Not a big volume It’s OK, CB can handle small quantity of data

• DB have to manage data TTL

Yes CB can do it

• Data model : K/V Yes

• Multiple writes at the same time

OK, this is possible with memcached protocol

• High availabilityClustering is built in, no downtime

I need to store sessions

QUICK EXAMPLE

USE ONLINE DATABASE / BE READY TO TEST IN JUST A FEW MINUTES NO NEED TO TRASH YOUR COMPUTER

DON’T BE THAT GUY

DO NOT USE A TECHNOLOGY BECAUSE YOU <3 IT OR BECAUSE IT’S HYPE : USE IT BECAUSE IT FITS YOUR NEEDS

BALANCE YOUR LEARNING CURVE WITH THE TIME SAVED

DO NOT CREATE MONSTERS

COMMON MISTAKES

DO NOT USE MEMORY AS DATABASELIKE : SHARED / GLOBAL VARIABLE, CACHE “IN THE CODE”, INTENSIVE SESSION USAGE…

DO NOT USE A VARIABLE FOR MORE THAN ONE REQUEST

2 + 2 = 4

FOR SAME INPUT, SAME OUTPUT

GET do not change data on server

BE HTTP CONSISTENT

And data will be lost

CODE WILL FAIL

DO NOT USE FILE SYSTEM AS DATASTORE

File system are POSIX compliant

• POSIX is ACID• POSIX is powerful but is bottleneck • File System is nightmare of ops • File System is create coupling (host provider/OS/language)• Free SPOF multi tenant File System is a unicorn

STORE IN DATABASE, OR DATASTORE LIKE S3 (AWS) DEDICATED TO FILE MANAGEMENT

CAREFUL USE OF DARK MAGIC

SPLIT THE CODE : MODULES

• Smallest code base

• Deploy as service for each other

• Focus on best technology for a problem

SCALE YOUR TEAMMODULARIZE YOUR TEAM

USE EVENT BROKER TO MODULARIZE YOUR APP• AMQP

• Celery

• 0MQ

• Redis

• JMS

• Some case : hadoop, akka…

• …

CRON is not an event queue

MAKE HARD COMPUTATION ASYNC

ALWAYS USE A REVERSE PROXY

Y U NOT USE ONE ?

DO NOT BUILD “THE SERVER” WITH NO DOC

USE PROCESS DEPLOYMENT

EASY MOVING OR INCIDENT MANAGEMENT

KEEP CALM UNDER FIRE

TRACK BUG & GET METRICS

Quentin ADAM

Twitter : @waxzce

THX FOR LISTENING & QUESTIONS TIME