Evolving toward microservicesHow HomeDepot.com made the switch

About me

Christopher GrantSr Architect HomeDepot.com

cgrantcgrant

Building the monolith

1996

2011

• 2 GB Java Deploy that took an hour

• Locking SCM (Clear Case) with no CI

• 3 Month long release Cycles

• 2-4 hour deploy outages

Breaking Down the Monolith

Our Objective

• Increase the rate of change

• Increase number developers

• Maintain and enhance operations

Agile

Domain Spaces

Continuous Integration Tooling

APIs

Feature Throttles

Result

2011 2015

Apps 1 30

Sales $1b $5b

Developers 170 300

Deploy frequency 3 month Weekly

2015 began moving to cloud & micro services

But wait

Theres more!!

Evolving Architectures

Iterative Architecture?

Changing the wheels while driving?

Evolutionary Architecture

Start with a vision

• Have a vision

• Understand your objectives

• Choose what matters

• Implement in stages

Decompose & Define Boundaries

• Understand business products & domains

• Identify people structures

• Review data models

• Look for the hard things

Architect for Change

• Prepare for future changes

• Be proactive not reactive

• Delay until the last responsible moment

• Expect but minimize future rework

Implement Safely

• Automate early and often

• Consider in-place and green-field

• Utilize feature switches and traffic throttles

• Encourage separation and independence