HOW TO SCALE YOUR APP SOME ADVICE FROM THE GUY WHO HANDLES YOUR APP UPTIME

QUENTIN ADAM AT

@WAXZCE2013

MY DAY TO DAY WORK : CLEVER CLOUD, MAKE YOUR APP RUN ALL THE TIME

And learn a lot of things about your code, apps, and good/bad design…

KEEP YOUR APPS ONLINE. MADE WITH NODE.JS, SCALA, JAVA, RUBY, PHP, PYTHON, GO…

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

IF YOU ONLY SCALE UP, YOU GONNA HAVE A BAD TIME

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

TRUST YOUR MIDDLEWARE

USE AN EVENT BROKER TO MODULARIZE YOUR APP

USE AN EVENT BROKER TO MODULARIZE YOUR APP

• AMQP

• Celery

• 0MQ

• Redis

• JMS

• Even some http chunk or websocket

• Some case : hadoop, akka…

• …

CRON + FS IS NEITHER AN EVENT QUEUE NOR A JOB SCHEDULER

CHOOSE YOUR 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 ?

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

{P, DB, S} aaS

USE OPS FREE SOLUTION TO LEARN AND START

COMMON MISTAKES

DO NOT USE THE FILE SYSTEM AS A DATASTORE

File system are POSIX compliant

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

STORE IN DATABASE, OR IN A DATASTORE LIKE S3/RIAKCS DEDICATED TO FILE MANAGEMENT

DO NOT USE THE FILE SYSTEM AS A DATASTORE

LOGS IN FILES I HATE IT

USE STREAMING I/O TO STREAM DATA DIRECTLY TO DATABASE

HTTP Post dataTemporarily store as file

or in memory

Store it into your storage

backend

Say OK to client

USE STREAMING I/O TO STREAM DATA DIRECTLY TO DATABASE

HTTP Post data

Directly stream your data to

Storage backend

Say OK to client

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

F(X) = X * 2F(2) = 4^ WE ASSUME THATFOR SAME INPUT, SAME OUTPUT

IT’S LIKE MATH FUNCTION

Example : GET should not change data on server

RESPECT HTTP

data will be lost

CODE WILL FAIL

CAREFUL USE OF DARK MAGIC

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

MAKE HARD COMPUTATION ASYNC

SPLIT THE CODE : MODULES

• Smallest code base

• Deploy as service for each other

• Focus on best technology for a problem

SMALLEST CODE BASE POSSIBLE FOR EACH PROGRAM

EACH MODULE IS VIEWED AS A SERVICE BY OTHERSHTTP OR AMQP COMUNICATION

OR AS A CLIENT

USE EVENT BROKER TO MODULARIZE YOUR APP• AMQP

• Celery

• 0MQ

• Redis

• JMS

• Some case : hadoop, akka…

• …

CRON is not an event queue

FOCUS ON THE BEST TOOL TO SOLVE YOUR PROBLEM

SCALE YOUR TEAMMODULARIZE YOUR TEAM

THE POWER OF REWRITE EVERYTHING

SMALL CODE BASE + MULTIPLE TECHNOLOGIES = LEGACY KILLER

REWRITE IS QUICK BECAUSE YOU KNOW ALL THE PROBLEMS BEFORE IT HAPPENS

HAPPY DEVELOPER WORKS BETTER : ARE YOU HAPPY WHEN YOU START YOUR IDE?

DO NOT BUILD “THE SERVER” WITH NO DOC

USE PROCESS DEPLOYMENT

THE GOOD WAY OF DEPLOY AN APP :

git push

EASY MOVING OR INCIDENT MANAGEMENT

KEEP CALM UNDER FIRE

ALWAYS USE A REVERSE PROXY

Y U NO USE ONE ?

TRICK WITH OTHERS PROTOCOLS

TRACK BUG & GET METRICS

I’m @waxzce on twitter

I’m the CEO of

A PaaS provider, give it a try ;-)

THX FOR LISTENING & QUESTIONS TIME