This document summarizes Jessica Tai's presentation about Airbnb's migration from a monolithic Ruby on Rails application to a microservices architecture. Some key points: 1) Airbnb initially used a monolithic architecture but encountered scalability issues as traffic grew such as slower deployments and more incidents. 2) They migrated to a service-oriented architecture with loosely coupled services organized by domain and request lifecycle. 3) Migrating involved incrementally moving pieces of the monolith like data models, business logic, and views to standalone services over time. 4) They employed techniques like dual writes, response comparisons, and replaying production traffic to migrate services safely while minimizing risk.

1. Airbnb’sGreatMigration:
BuildingServicesatScale
JESSICA TAI / 25 OCTOBER 2019 / CODEMOTION MILAN

2. @jessicamtai
2014

3. @jessicamtai
2015+

4. @jessicamtai
Hi,I’mJessica.
Ipairprogram
withmycorgi.

5. Why migrate? Service design tenets
Incremental
comparison
Best practices Results
Decomposition
@jessicamtai

6. Why migrate?
Best practices Results
Incremental
comparison
Service design tenets
Decomposition
@jessicamtai

7. Why migrate?
Best practices Results
Incremental
comparison
Service design tenets
Decomposition
@jessicamtai

8. Why migrate?
Best practices Results
Incremental
comparison
Service design tenets
Decomposition
@jessicamtai

9. Why migrate?
Best practices Results
Incremental
comparison
Service design tenets
Decomposition
@jessicamtai

10. Why migrate?
Best practices Results
Incremental
comparison
Service design tenets
Decomposition
@jessicamtai

11. Monorail,ourRubyonRailsmonolith
@jessicamtai

12. Easystartwithmonoliths
EARLY AIRBNB
Client traffic
Shared
database
Monorail
Data access query
Business logic
Presentation view
@jessicamtai

13. @jessicamtai

14. @jessicamtai

15. WHY DECIDE TO MIGRATE?
@jessicamtai

16. @jessicamtai

17. Moreincidents Slowerdeploytrains
@jessicamtai

18. Moreincidents Slowerdeploytrains
@jessicamtai

19. Oursolution:Service-orientedarchitecture(SOA)
NETWORK OF LOOSELY-COUPLED SERVICES
Client
API gateway
Service1
Service2
Database2Database3
Service3
@jessicamtai

20. CheckoutpageinSOA
Business travel service
Cancellation service
Home demand service
Pricing service
Home service
Reservation service
Messaging service
@jessicamtai

21. SERVICE DESIGN TENETS
@jessicamtai

22. Servicesownreads&writes
totheirdata @jessicamtai

23. Servicesaddressaspecificconcern
@jessicamtai

24. Avoidduplicatefunctionality
https://www.flickr.com/photos/popilop/331357312
@jessicamtai

25. Datamutationspropagate
viastandardevents @jessicamtai

26. Buildforproduction
@jessicamtai

27. DECOMPOSE BY
REQUEST LIFE CYCLE
@jessicamtai

28. Requestlifecycle
Client traffic
Shared
database
Monorail
Data access query
Business logic
Presentation view
V1: MONORAIL
@jessicamtai

29. Requestlifecycle
Monorail
API traffic
Routing & view
Business logic, model, data
via services
Client traffic
V2: MONORAIL & SERVICES
@jessicamtai

30. MIDDLE TIER
Shared business logic
Servicetypes
STRICT FLOW OF DEPENDENCIES
PRESENTATION
Synthesize
DERIVED DATA
Shared context, multiple sources
DATA
Entity read and writes
@jessicamtai

31. MIDDLE TIER
Shared business logic
PRESENTATION
Synthesize
DERIVED DATA
Shared context, multiple sources
DATA
Entity read and writes
Servicetypes
STRICT FLOW OF DEPENDENCIES
@jessicamtai

32. MIDDLE TIER
Shared business logic
PRESENTATION
Synthesize
DERIVED DATA
Shared context, multiple sources
DATA
Entity read and writes
Servicetypes
STRICT FLOW OF DEPENDENCIES
@jessicamtai

33. MIDDLE TIER
Shared business logic
DERIVED DATA
Shared context, multiple sources
DATA
Entity read and writes
PRESENTATION
Synthesize
Servicetypes
STRICT FLOW OF DEPENDENCIES
@jessicamtai

34. PRESENTATION
Synthesize
MIDDLE TIER
Shared business logic
DERIVED DATA
Shared context, multiple sources
DATA
Entity read and writes
Servicetypes
STRICT FLOW OF DEPENDENCIES
@jessicamtai

35. Homes
H O S T E D B Y K I T T Y · A P T O S , C A L I F O R N I A
Mushroom Dome
@jessicamtai

36. Homes data
service
Shared
database
Monorail
Data access query
Business logic
1.Migratingcoredatamodels
Presentation view
Homes
database
@jessicamtai

37. Homes data
service
Shared
database
Monorail
Data access query
Business logic
2.Migratingcorebusinesslogic
Presentation view
Homes
database
Pricing derived
data service
Pricing trends
data store
@jessicamtai

38. Homes data
service
Shared
database
Monorail
Data access query
Business logic
3.Migratingcoreproductviews
Presentation view
Homes
database
Pricing derived
data service
Pricing trends
data store
Checkout
presentation
service
@jessicamtai

39. Homes data
service
Shared
database
Monorail
Data access query
Business logic
4.Migratingcoreproductwrites
Presentation view
Homes
database
Homes
validation
middle-tier
Pricing derived
data service
Pricing trends
data store
Checkout
presentation
service
@jessicamtai

40. Requestlifecycle
Monorail
API traffic
Routing & view
Client traffic
V2: MONORAIL & SERVICES
@jessicamtai
Business logic, model, data
via services

41. Requestlifecycle
API gateway
Middleware
Session data
service
Authentication
data service
Oauth data
service
Risk derived
data service
...
Request
context
Presentation, logic, data
V3: SOA & API GATEWAY
Routing
@jessicamtai

42. Requestlifecycle
API gateway
Middleware
Session data
service
Authentication
data service
Oauth data
service
Risk derived
data service
...
Request
context
Web rendering
service
HTML viewV3: SOA & API GATEWAY
Routing
@jessicamtai
Presentation, logic, data

43. Monolith
world
Services
world
TheFutureTM
@jessicamtai

44. Migration
world
Monolith
world
Services
world
@jessicamtai

45. COMPARE FOR DIFFERENCES
@jessicamtai

46. Dualreadcomparison
WaitRamp&waitCompareGate
Admin web UI
configuration
1% traffic Gradual
increments
Gather traffic
patterns
All traffic through
service only
Switch
Read path A
Read path BMonorail
Service
Database
@jessicamtai

47. Dualreadcomparison
WaitRamp&waitCompareGate
Admin web UI
configuration
1% traffic Gradual
increments
Gather traffic
patterns
All traffic through
service only
Switch
Monorail
Service
Database
Response A
Response B
Consumer +
offline
comparison
framework
@jessicamtai

48. Dualreadcomparison
WaitRamp&waitCompareGate
Admin web UI
configuration
1% traffic Gradual
increments
Gather traffic
patterns
All traffic through
service only
Switch
Monorail
Service
Database
Response A
Response B
Consumer +
offline
comparison
framework
@jessicamtai

49. Dualreadcomparison
WaitRamp&waitCompareGate
Admin web UI
configuration
1% traffic Gradual
increments
Gather traffic
patterns
All traffic through
service only
Switch
Monorail
Service
Database
Response A
Response B
Consumer +
offline
comparison
framework
@jessicamtai

50. Dualreadcomparison
WaitRamp&waitCompareGate
Admin web UI
configuration
1% traffic Gradual
increments
Gather traffic
patterns
All traffic through
service only
Switch
Production
traffic
Monorail
Service
Database
Response A
Response B
Consumer +
offline
comparison
framework
@jessicamtai

51. Dualreadcomparison
WaitRamp&waitCompareGate
Admin web UI
configuration
1% traffic Gradual
increments
Gather traffic
patterns
All traffic through
service only
Switch
100%
Production
traffic
Monorail
Service
Database
Response A
Response B
Consumer +
offline
comparison
framework
@jessicamtai

52. Dualreadcomparison
WaitRamp&waitCompareGate
Admin web UI
configuration
1% traffic Gradual
increments
Gather traffic
patterns
All traffic through
service only
Switch
100%
Monorail
Service
Database
Response A
Response B
Consumer +
offline
comparison
framework
@jessicamtai

53. Dualreadcomparison
WaitRamp&waitCompareGate
Admin web UI
configuration
1% traffic Gradual
increments
Gather traffic
patterns
All traffic through
service only
Switch
Monorail
Service
Database
Response A
Response B
Consumer +
offline
comparison
framework
@jessicamtai

54. Dualreadcomparison
WaitRamp&waitCompareGate
Admin web UI
configuration
1% traffic Gradual
increments
Gather traffic
patterns
All traffic through
service only
Switch
Monorail
Service
Database
The only read path
@jessicamtai

55. Writecomparison
SHADOW DATA SERVICES
Presentation service
Write validation
middle tier service
Write path A
Write path B
Data service
(production)
Data service
(shadow)
Consumer +
offline comparison
framework
Monorail
Payload A Payload B
@jessicamtai

56. s
Writecomparison
DUAL WRITE TO SEPARATE DATABASES
Presentation service
Write validation
middle tier service
The only write path
Data service
(shadow)
Monorail
@jessicamtai

57. APIgatewaycomparison
API gateway
Presentation service
Product logic
Monorail
Product logic
Original request
(no middleware applied)
Shadow request
with context
Add request context
@jessicamtai
Middleware
@jessicamtai
Shadow
request copy

58. APIgatewaycomparison
API gateway
Presentation service
Product logic
Request
with context
Middleware
@jessicamtai

59. Incrementalmigration
@jessicamtai

60. ! Production traffic with partially complete service
○ e.g. batch API /loadUsers
○ Fetch users only by user id
! Unblock clients
Migratebyendpoint
@jessicamtai

61. Migratebyattribute
Service Monorail
Database
Read migrated
attributes
Read not-yet-migrated
attributes
Database
Presentation service
Production traffic
@jessicamtai

62. SOA BEST PRACTICES
@jessicamtai

63. Frameworks
Auto-generate code
Testing&deploying
Replay production traffic
Observability
Standard templates
Standardizeservicebuilding
SCALE WITH CONSISTENCY
@jessicamtai

64. Service
Service&clientsetup
Business logic
@jessicamtai

65. Service
Service&clientsetup
Business logic
Endpoint logic
Server
transport
@jessicamtai

66. Service
Service&clientsetup
Business logic
Endpoint logic
Server
transport
Java client
Ruby client
Client
transport
Client
transport
@jessicamtai

67. Service
Service&clientsetup
Business logic
Server metrics
Server
diagnostics
Startup /
teardown
Endpoint logic
Metrics
Data
validation
Server
transport
Server
resilience
Java client
Ruby client
Metrics
Client
transport
Data
validation
Error
handling
Resilience
Metrics
Client
transport
Data
validation
Error
handling
Resilience
Type
checking
@jessicamtai

68. Service
Endpoint logic
Service&clientsetup
Business logic
Server metrics
Server
diagnostics
Startup /
teardown
Dashboard
Dashboard
Alert
Alert
Alert
Runbook
documentation
Metrics
Data
validation
Server
transport
Server
resilience
Java client
Ruby client
Metrics
Client
transport
Data
validation
Error
handling
Resilience
Metrics
Client
transport
Data
validation
Error
handling
Resilience
Type
checking
@jessicamtai

69. Service
Endpoint logic
Service&clientsetup
Business logic
Server metrics
Server
diagnostics
Startup /
teardown
Dashboard
Dashboard
Alert
Alert
Alert
Runbook
documentation
Metrics
Data
validation
Server
transport
Server
resilience
Java client
Ruby client
Metrics
Client
transport
Data
validation
Error
handling
Resilience
Metrics
Client
transport
Data
validation
Error
handling
Resilience
Type
checking
@jessicamtai

70. FrameworksusingThriftIDL
@jessicamtai

71. IDL
Service
Endpoint logic
Business logic
Server metrics
Server
diagnostics
Startup /
teardown
Dashboard
Dashboard
Alert
Alert
Alert
Runbook
documentation
Metrics
Data
validation
Server
transport
Server
resilience
Java client
Ruby client
Metrics
Client
transport
Data
validation
Error
handling
Resilience
Metrics
Client
transport
Data
validation
Error
handling
Resilience
Type
checking
@jessicamtai

72. ThriftIDL
API FRAMEWORK
/** Batch request for demo data */
struct LoadSomeDataRequest {
1: optional set<i64> ids
/** Some extra context baz */
2: optional bool fooBar (personal_data)
}
@jessicamtai

73. ThriftIDL
API FRAMEWORK
/** id to data response */
struct LoadSomeDataResponse {
1: optional map<i64, SomeData> data
}
@jessicamtai
/** Batch request for demo data */
struct LoadSomeDataRequest {
1: optional set<i64> ids (personal)
/** Some extra context baz */
2: optional bool fooBar
}

74. /** /loadSomeData batch endpoint */
LoadSomeDataResponse loadSomeData
(1: LoadSomeDataRequest request)
throws (1: SomeException exception1)
(accept_replay = "true", rate_limit = "true")
ThriftIDL
API FRAMEWORK
@jessicamtai

75. Thrift annotations
@jessicamtai

76. Block comments
from .thrift file
@jessicamtai

77. TRY TRY AGAIN SUCCESS
FAIL FAST
@jessicamtai

78. Separateasync
workerthreadpools
Graceful
degradation
@jessicamtai

79. Testing&deploying
TIMELINE
ProductionCanaryDiffyStaging
@jessicamtai
Localdev

80. Testing&deploying
TIMELINE
ProductionCanaryDiffyStagingLocaldev
Dev
environment
supports shared
dev services
@jessicamtai

81. Testing&deploying
TIMELINE
Replayed
production
traffic with
other staging
services
ProductionCanaryDiffyStagingLocaldev
@jessicamtai

82. Testing&deploying
TIMELINE
ProductionCanaryDiffyStagingLocaldev
Compare
responses from
staging against
production
@jessicamtai

83. RegressionTesting
DIFFY
Staging
(new code)
Primary
(old code)
Secondary
(old code)
Raw response
differences
Non-
deterministic
noise
Filtered
response
differences
Diffy
Replayed traffic
github.com/twitter/diffy
@jessicamtai

84. Testing&deploying
TIMELINE
ProductionCanaryDiffyStagingLocaldev
Deploy to single
instance of
production
@jessicamtai

85. Testing&deploying
TIMELINE
ProductionCanaryDiffyStagingLocaldev
Confidently
deploy to prod
@jessicamtai

86. @jessicamtai

87. @jessicamtai

88. PROGRESS SO FAR?
@jessicamtai

89. 2016:
One small infra team
Airbnb’s SOA progress
@jessicamtai

90. 2016:
One small infra team
2019:
Whole engineering org
Airbnb’s SOA progress
@jessicamtai

91. IDL services in production0
450+
@jessicamtai

92. ! Faster build & deploy times
○ Hours (Monorail) to minutes (service)
○ Fewer reverts
! Quicker bug fixes
! Increased developer productivity happiness
Promisingresults
SUCCESS
@jessicamtai

93. ! Lower latency from parallelization
○ Ruby monorail single-threaded
○ Java services multi-threaded
! Search results page 3x faster
! Homes description page 10x faster!
Latencyresults
SUCCESS
@jessicamtai

94. 500+ 67%
Deploys in MonorailEngineers
2016
@jessicamtai

95. 500+ 67%
Deploys in MonorailEngineers
2000+ 3%
2016
2019
@jessicamtai

96. Production traffic via API Gateway
75%
@jessicamtai

97. CheckoutpagerequiredmessageinSOA Checkout presentation
Home data
Reservation data
Review data
Pricing
derived data
Home demand
derived data
Cancellation
derived data
Business travel
derived data
Messaging data
@jessicamtai

98. SOAhasitschallenges
CAUTION
@jessicamtai

99. Distributedservices
CAUTION
@jessicamtai

100. Multiple,isolateddatabases
CAUTION
@jessicamtai

101. Complexserviceorchestration
CAUTION
@jessicamtai

102. ! Prepare for a long commitment
! Define service building principles
! Decompose incrementally
! Scale with auto-generating frameworks, tools
SOAmigration
TAKEAWAYS
@jessicamtai

103. Lookbothways
duringyourGreatMigration
@jessicamtai

104. @JESSICAMTAI
CODEMOTION MILAN 2019