Microservices testing in distributed systems

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Microservices testing in distributed systems
IsaVilacides
Engineering Director at CloudBees

AGENDA
• Monolith vs microservices
• Traditional model of testing and its challenges in
distributed systems
• Consumer driven contract testing with PACT
• A real life example in action
• Post deployment verification
• Safe rollouts

CLASS PRE-REQUISITES
• Have a local copy of https://github.com/vilacides/
contractTestingExample updated to the latest version
• Java 8 and Maven 3.9
• Have an IDE configured to run maven projects/terminal
• Basic Java knowledge

WHY DID I PUTTHISTALKTOGETHER?

MONOLITHVS MICROSERVICE
ARCHITECTURE

Monolith vs microservice architecture

TRADITIONALTESTING PYRAMID IN
MONOLITHS AND ITS CHALLENGES IN
DISTRIBUTED SYSTEMS

TESTING PYRAMID

ENDTO ENDTESTS
• In the monolith
◦ Slow
◦ Unreliable
◦ Difficult to maintain
◦ Difficult to debug
◦ Test real integration end to end
by spinning up the one thing
• In distributed systems
◦ Slow
◦ Even more unreliable
◦ Difficult to maintain
◦ Difficult to debug
◦ Test real integration end to end
by spinning up N things

UNIT AND INTEGRATIONTESTS
• In the monolith
◦ Fast
◦ Reliable
◦ Easy to maintain
◦ Easy to debug
◦ They do not test the real
integrations, they are based on
assumptions
• In distributed systems
◦ Not that fast integration tests
◦ Not that reliable
◦ Easy to maintain
◦ Easy to debug
◦ Require to mock several
services, they are based on
assumptions

WHAT IFYOUR ASSUMPTIONS CHANGE?

It relies on the
developers to watch for
these changes

WE NEEDED SOMETHINGTHAT ALLOWED US
TO DEVELOP INDEPENDENTLY, GOING FAST
WITHOUT BREAKINGTHINGS

WHAT IF WE COULD GETTHE BEST OF
BOTH WORLDS?

CONSUMER DRIVEN CONTRACTTESTING
WITH PACT

CONTRACTTESTING WITH PACT

What do you need to make it work?
• Consumers need to clearly state their expectations
• Communication
• Red is red

What does consumer contract driven testing give you?
• Fast feedback in isolation
• Early detection in both sides
• Enables communication

A REAL LIFE EXAMPLE IN ACTION

• What is PACT good for?
◦ End to end integration testing
that is fast and reliable
◦ All the things API!
• What PACT doesn’t replace
◦ Testing that performs UI
interactions

RESHAPINGTHE PYRAMID

• We have reduced the need of end to end tests
• We ultimately want to go fast without breaking things, but
things will break so you priority becomes to be the first one
to know that things went wrong in production

• Post deployment verification becomes more important:
• Deployment health checks
• Monitoring

• Health checks answer from easy to more complex
questions through API calls:
• Are you up?
• How long did it take you to respond?

EXAMPLE

Monitoring helps you understand your service evolution:
• Understand how your services normally behave
• % of 500 responses per second
• Establish thresholds
• Measure and monitor
• Raise alerts
• React

By the time you react to your alerts
your customers are already affected

SAFE ROLLOUTS
DOGFOODING, FEATURE FLAGS AND STAGED DEPLOYMENTS

FEATURE FLAGS

FEATURE FLAGS
// Test environment
{
“display_my_new_feature”: true
}
// Live environment
{
“display_my_new_feature”: false
}

FEATURE FLAGS
• What FF are good for
◦ Experimentation
◦ Safe rollouts and rollbacks
• When FF get tricky
◦ Handling different combinations
◦ Features that require schema
changes in databases

CANARY ROLLOUTS

DOGFOODING

WHAT WE LEARNT

WHAT WE LEARNT
• Focus on integrations between consumers and providers
and have strong defined contracts
• If something goes wrong in production you want to be the
first one to know
• Reduce the surface of customer that get your changes

THANKYOU!
QUESTIONS?
IsaVilacides - @vilacides

SOURCES
• https://github.com/vilacides/contractTestingExample
• pact.io
• https://dius.com.au/2017/09/22/contract-testing-serverless-
and-asynchronous-applications/
• https://github.com/vilacides/contractTestingExample

Microservices testing in distributed systems

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