Over the past 10 years, FINN transitioned their monolithic Java application built on a Sybase database to a microservices architecture running on PostgreSQL, Kafka and Kubernetes. They broke the monolith into independent services but still struggled with dependencies on the legacy Sybase database. They learned it takes a long time to fully migrate and should focus on delivering value incrementally. While the transition is still ongoing, they have made major progress deploying new services and migrating data and are now 93% in Kubernetes with the goal of moving completely to the cloud.

1. 1
10 years of microservices - and we
still haven’t slain that dragon!
NDC 2019-06-19

2. https://flic.kr/p/8nhwv3

5. Henning Spjelkavik
Senior software developer / Architect
Board of Directors
@spjelkavik
FINN travel - kart.finn.no
Kafka - Architecture - Tcpdump - SEO - Nodejs - Java - Smidig
Nybygg - Eiendom - Torget - Business center - DDD - Business cases -
Garbage collection - Linux - EWC - Jstack - Yourkit
Mexico, Morocco, Spain, France, Sweden, Poland, Chile & Hungary

6. Quiz

7. 7
96%

8. 8
1182

10. 10
586

13. Data 2008
1 Sybase database (The Legacy DB)
(+ data warehouse)

14. Data 2019
22 postgres clusters, 128 pg databases
1337 kafka topics (564 private, 532 public)
37.000 messages/s (avg 24h)
1 Sybase database (The Legacy DB)
(+ data warehouse + data lake stuff)

15. Where are we today?
What did we learn?
What do we mean by "out of legacy"?
10 years - major events
Conclusion
Outline

16. 10 years of breaking up the
monolith
- and we still haven’t found
what we’re looking for

17. Target 99.9% uptime / monthMay 2019: 99.99%. YTD 99.97%
1700M NOK revenue 2018

18. What did we learn?

19. “What problem are you trying to
solve?”

20. “Not all of a large system will be
well designed”
- Eric Evans

21. Out of legacy?
What do we mean?

22. https://flic.kr/p/2aUhP1q

24. https://flic.kr/p/dihGds

25. Out of legacy?
What do we mean?

26. Out of legacy - What (technical) problem does it solve?
1. Have to change the code and wait for deploy of the big monolith
2. Synchronous database call to legacy database
3. Synchronous call to a service, that calls the legacy database (Trans, New APIs,
Ad-lookup-server)
4. Asynchronous dependency on data from the legacy database
a. asking a replica/duplicate, or
b. consuming a stream
5. Conforming to the model, possible to map both ways (Ad-input-server)
6. Same meta model
a. e.g own idea on how we model an ad, but the service own their model
b. possibly one way mapping
7. Separate ways - no relationship
It may be poor business value in going all the way to level 7.

27. Timeline

28. 2004
FinnTech launched internationally
The monolith called iAd
Java & stored procedures in Sybase
Presentation
Business logic
Data access
Sybase

29. 2006
FINN kart (Maps) outside the monolith

30. 2009
First “modules” were separated out
Presentation
Business Logic - iAd
Data access – stored procedures
Login User
Sybase
SSO

31. Out of legacy - What (technical) problem does it solve?
1. Have to change the code and wait for deploy of the big monolith
2. Synchronous database call to legacy database
3. Synchronous call to a service, that calls the legacy database (Trans, New APIs,
Ad-lookup-server)
4. Asynchronous dependency on data from the legacy database
a. asking a replica/duplicate, or
b. consuming a stream
5. Conforming to the model, possible to map both ways (Ad-input-server)
6. Same meta model
a. e.g own idea on how we model an ad, but the service own their model
b. possibly one way mapping
7. Separate ways - no relationship

32. 2012-
Platform project;
Later turned into new Order, Product, Billing and Ad-insertion
Mobile web

33. 2014
Freeze of the legacy (iAd) - nothing new should be made here
Officially renamed “microservices”
Requirements / definition:
https://confluence.schibsted.io/pages/viewpage.action?pageId=23581198

34. Sam Newman

35. What is a microservice? Requirements (2014)
- Deployed independently of other services
- Have a single owner (team)
- Ownership of the data it needs (own database)
=> avoid integration through the database
- Have an API - or listen/publish messages
- Healthcheck
- Monitoring
- Proper API versioning - can be upgraded without requiring the clients to
update
- Don’t crash even if dependencies are down

36. Out of legacy - What (technical) problem does it solve?
1. Have to change the code and wait for deploy of the big monolith
2. Synchronous database call to legacy database
3. Synchronous call to a service, that calls the legacy database (Trans, New APIs,
Ad-lookup-server)
4. Asynchronous dependency on data from the legacy database
a. asking a replica/duplicate, or
b. consuming a stream
5. Conforming to the model, possible to map both ways (Ad-input-server)
6. Same meta model
a. e.g own idea on how we model an ad, but the service own their model
b. possibly one way mapping
7. Separate ways - no relationship

37. The FINN “Death Star - 2015” - a Distributed Monolith?
FINN consisted of more than 200+
highly coupled services (RPC), resulting
in a “distributed monolith”

38. Udi Dahan,
Eric Evans,
Fred George

39. 2016
New Order, Product, Billing and Ad-insertion in place for all direct customers
(not Partners) - integrating over Kafka
95% of the volume; only 30% of the revenue is running on new stacks
Data is available on Kafka from Legacy
Responsive web site (for end users) - outside iAd
Out of Sybase project (cancelled after 6 months)

40. Out of legacy - What (technical) problem does it solve?
1. Have to change the code and wait for deploy of the big monolith
2. Synchronous database call to legacy database
3. Synchronous call to a service, that calls the legacy database (Trans, New APIs,
Ad-lookup-server)
4. Asynchronous dependency on data from the legacy database
a. asking a replica/duplicate, or
b. consuming a stream
5. Conforming to the model, possible to map both ways (Ad-input-server)
6. Same meta model
a. e.g own idea on how we model an ad, but the service own their model
b. possibly one way mapping
7. Separate ways - no relationship

41. 2017
We want to move to the cloud
Fiaas - our deployment platform built on kubernetes

42. 2018
New business center (“control panel”)
Make it look good; fetch data where
it’s needed
Packages (for direct customers)
GDPR
Sybase
Postgres Postgres Postgres
Kafka

43. GDPR
Take out and delete - simplified view
Kafka
Privacy broker
(Saga per user request)
User
Recommendation
Messaging
Travel
+++

45. Moving to the cloud
The elephant in the data center: Sybase on Sparc/Solaris

46. “Spinning rust is dead. SANs are now a complete waste of time.”
- Adrian Cockcroft, 2008

47. Sybase migrated off Sparc/Solaris to
Linux
Moving main services towards a public
cloud;
93% of apps already in kubernetes
2019
Sybase
Postgres Postgres Postgres
Kafka

49. Learnings
It did not go as fast as we dreamed.
Have a roadmap, but meanwhile make it better to live with what exists.
Encourage and enable teams to make services on the outside
If every client (downstream) need to rewrite to realise benefits - when can you realistically
be finished? Is it still worth the effort? (or at what speed)
Good Devops/ “Accelerate”-metrics enables! (Lead Time, Deployment Frequency, Mean Time
to Restore)

50. There wasn’t (yet) a strong
business need of moving out of
the legacy

51. Done differently
Adjust expectations: complicated system; - accept where you are
it takes a looong time to “rewrite everything”.
Use lipstick to offer customer/user/business value today, accept some kludges
Consider to separate parts of the database first (Sam Newman)
Be aware of “this time we’re gonna do it right”-syndrome or NIH

52. We have a direction
and a roadmap out of legacy

53. https://flic.kr/p/2p8WCx

54. Henning Spjelkavik
@spjelkavik
Remember:
“Not all of a large system will be well designed” - Eric Evans
“Successful visionaries start from where they are, what they have, and
what their customers have.” - Tom Gilb
“What problem are you trying to solve?”
Thank you!