Move Fast and Consumer Driven Contract Test Things

Slide 1

Slide 1 text

Making SoundCloud’s µ-services safe to deploy Move Fast and Consumer-Driven- Contract-Test Things microXchg Berlin 2017

Slide 2

Slide 2 text

1.5 years @ SoundCloud Discovery Cluster Backend Engineer @alonpeer

Slide 3

Slide 3 text

About SoundCloud a cloud full of sounds 135M tracks, 175M listeners, 12 hours/minute 300+ services / 50+ teams

Slide 4

Slide 4 text

Agenda ● Testing, monolith style ● My first steps @ SoundCloud ● Introducing contract tests ● Pactifying our services ● Caveats ● QA Q&A

Slide 5

Slide 5 text

Testing, monolith style

Slide 6

Slide 6 text

● One service, one client ● API changes are easy ● One client team to sync with for migrations ● API deprecation is easy Testing, monolith style The good ol’ days

Slide 7

Slide 7 text

● Different requirements per client => Code complexity increases ● Harder to deploy without breaking at least one client Testing, monolith style Mo clients, mo problems

Slide 8

Slide 8 text

● More manual QA expensive, slow, prone to human error, doesn’t scale ● More end-to-end tests Maintenance nightmare, flaky, slow, creates bottlenecks Testing, monolith style Mo clients, mo problems

Slide 9

Slide 9 text

My first steps @ SoundCloud

Slide 10

Slide 10 text

My first steps @ SoundCloud Whoa, micro-services

Slide 11

Slide 11 text

My first steps @ SoundCloud Testing strategy E2E Unit Integration

Slide 12

Slide 12 text

My first steps @ SoundCloud Digging into post-mortems © ofsmallthings

Slide 13

Slide 13 text

My first steps @ SoundCloud “A lack of trust in the acceptance tests caused us to largely ignore the warnings they generated.” “We couldn’t figure out the impact of the broken acceptance tests, and assumed the only problem was the tests themselves, rather than the underlying code.” “The commit went through as there weren't any tests for the serialisation from the client to the backend.” Digging into post-mortems © ofsmallthings

Slide 14

Slide 14 text

Introducing contract tests

Slide 15

Slide 15 text

Introducing contract tests My daily routine © LockeSteerpike

Slide 16

Slide 16 text

Introducing contract tests My daily routine © rickandmorty.com

Slide 17

Slide 17 text

Unit tests are not enough Introducing contract tests “#cake” >> { result = call(“cake”) assert(result == “lie”) } GET “/cake”: return “lie”

Slide 18

Slide 18 text

Unit tests are not enough Introducing contract tests GET “/cake”: return “truth” “#cake” >> { result = call(“cake”) assert(result == “lie”) }

Slide 19

Slide 19 text

Unit tests are not enough Introducing contract tests import JsonLibFoo GET “/cake”: return toJson(current_state) // { “current_state” : “lie” } import JsonLibFoo “#cake” >> { result = fromJson(call(“cake”)) assert(result == “lie”) }

Slide 20

Slide 20 text

Unit tests are not enough Introducing contract tests import JsonLibBar GET “/cake”: return toJson(current_state) // { “currentState” : “lie” } import JsonLibBar “#cake” >> { result = fromJson(call(“cake”)) assert(result == “lie”) }

Slide 21

Slide 21 text

Introducing contract tests How this works? Consumer Provider End-to-End Test

Slide 22

Slide 22 text

Introducing contract tests How this works? Consumer Provider Unit Test Unit Test

Slide 23

Slide 23 text

Introducing contract tests How this works? Consumer Provider Unit Test Unit Test

Slide 24

Slide 24 text

Introducing contract tests How this works? ➢ Requesting “/cake”. ➢ Expecting a JSON response with a key “current_state”. ➢ Asserting deserialization of the response succeeds. import JsonLibFoo GET “/cake”: return toJson(current_state) // { “current_state” : “lie” } Consumer Provider

Slide 25

Slide 25 text

Pactifying our services http://pact.io

Slide 26

Slide 26 text

What’s Pact? Pactifying our services ● A family of frameworks designed for contract testing. ● Supports JSON over HTTP. ● Impl. for Java, Scala, Go, Ruby, .Net, Swift, JS etc. ● Tests run locally, no external dependencies.

Slide 27

Slide 27 text

What’s Pact? Pactifying our services Step 1: Define consumer expectations © pact.io

Slide 28

Slide 28 text

What’s Pact? Pactifying our services Step 2: Verify expectations on provider © pact.io

Slide 29

Slide 29 text

Consumer: client code

Slide 30

Slide 30 text

Consumer: client code

Slide 31

Slide 31 text

Consumer: client code

Slide 32

Slide 32 text

Consumer: client code

Slide 33

Slide 33 text

Consumer: client code

Slide 34

Slide 34 text

Consumer: client code

Slide 35

Slide 35 text

Consumer: client unit test

Slide 36

Slide 36 text

Consumer: client unit test

Slide 37

Slide 37 text

Consumer: client unit test

Slide 38