Adventures with

micro-Servicesby Anand Agrawal

@anand_agrawalanandagrawal84

What’s in it for you?

What?Why?How?When?

What are micro services?small independent composable

servicesthat do one thing well

What is the right size?

Unix philosophyWrite programs that do one thing well.

Write programs that work together.

cat | grep | sed | awk | ...

HTTP is the new pipe!

Single responsibility

Low coupling, high cohesion

Small, well defined interfaces

Object Oriented philosophy

“A 100k loc app is just 100 1k loc apps waiting to happen”

- Jeff Bay

used micro services?Why we

Once upon a time...

lots of legacy, no reuse

not flexible, high cost of change

concentrated complexity

no one knows how it works

90 year old business

independent small that do one thingcomposable

Adventure so far

25 VM’s in production

10 micro-services

one click deployment

60+ VM’s across environments

guess who does the deployments?

µService

DB

µService

DB

µService

DB

µService

DB

How did we start?

Solve small, valuable problems

Start with plain old services

When a service starts doing too much, extract a smaller one

Orders PaymentsCustomers

Legacy ResultsOrder Processing

Catalog (Games)

Looks like plain old services, what makes them ‘micro’?

single responsibility

1 service = 1 ‘resource’ (maybe 2!)

How do they communicate?

RESTful contracts

HTTP + JSON

Thumb Rules1 top level resource (2 at most)

bounded contexts

focus on contracts

extract cross cutting concerns

avoid coupling

sophisticated logging and monitoring

Orders PaymentsCustomers

Communications

Legacy ResultsOrder Processing

Scheduled Jobs

Error reporting

Catalog (Games)

Staying productive

client gems

ruby and rails

devops

automate, automate, automate

feature toggles over branches

How do I make a change and still stay sane?

Test It!

Unit Testsis my object doing what it should?

Contract Testsis my service doing what it should?

out of container

only test contracts, not implementation

Integration Testsare all my services playing nicely together?

testing distributed effects

testing async actions

Ship It!

“we’re effectively pushing the complexity from the application

into the infrastructure...”- James Lewis

Puppet Solo

Provisioning begins at home - Vagrant

Puppet scripts goes through CI just like app code

ImmutableServer

Provisioning

Continuous IntegrationUI# Services#Test# Puppet#Code#

Integra6on#

UAT#

Performance#

Produc6on#

10# 12# 20#

9#

8#

6#

3#

Configs#

15# 18#

4b3ee42#

with every checkin...run unit tests

run integration tests

run acceptance tests

build deployable package of the app

ship often!!

CI + CDenables

single-click deployment

so easy, our product owner does it!

it just works™

3 mins to production (~25 servers)

Cost of adding a service?

less than a day all the way to production

When to use micro-services?

Tradeoffs

benefit cost

small units of reuse/maintenance complex infrastructure

grow independently learning curve

scale independently network overhead

independent DB fragmented data

Questions?

Thanks!!