Splitting a Monolith Using Feature Flags

Presented at API World 2020

Transcript

1. Using Feature Flags How to Split a Monolith Joy Ebertz Sr Staff Engineer
2. Who am I? https://medium.com/@jkebertz
3. Who am I? • At Box • Worked on many aspects of splitting a monolith • Architecture • Authorization service • Service moving functionality • At Split • Work on a feature flagging system • Starting to think through splitting our monolith
4. Agenda • What are feature flags? • Why split a monolith? • Challenges of Splitting a Monolith • How can feature flags help?
5. What Are Feature Flags?
6. Other Terms • Feature Toggle • Feature Flip • Feature Switch • Conditional Feature • Split
7. Code Branch Controlled by GUI
8. Code Sample if (Treatments.ON .equals(_splitClient.getTreatment(orgId, Splits.MY_FEATURE.name()))) { // Do Something } else { // Do Something Else }
10. Code Sample if (Treatments.ON.equals(_splitClient.getTreatment(orgId, Splits.MY_FEATURE.splitName()))) { // Do Something } else { // Do Something Else }
11. Main Use-Cases • Releasing features • Production Testing • A/B/C Testing • Custom Packages • Temporary UI Customization
12. Main Use-Cases • Releasing features • Production Testing • A/B/C Testing • Custom Packages • Temporary UI Customization
13. Releasing Features • Separating Deploy from Release • Canary/Ramped Deployment • Off Switch
14. Deploy Release
15. </>
16. </> User
17. Prod User
18. Prod User
19. Prod Developer
20. Prod Developer
21. Prod User
22. Prod User Split
23. Prod User Split OFF OFF
24. Prod User Split OFF
25. Prod User Split OFF
26. Prod Split Product Owner OFF
27. Prod Split Product Owner ON
28. Prod User Split ON
29. Prod User Split ON
30. Prod User Split ON
31. Prod User Split ON
32. Prod Developer
33. Prod Developer
34. Prod User Split 10%
35. Prod User Split 20%
38. Why Should We Split a Monolith?
39. What do I mean by “Splitting a Monolith?”
46. Why Split a Monolith? Code Entanglement
52. Controllers Models Smarty Templates
53. Controllers Models Smarty Templates Actions!
54. Controllers Models Smarty Templates Actions
55. Controllers Models Smarty Templates Actions New Actions
56. New Actions Controllers Models Smarty Templates Actions New Actions
57. Controllers Models Smarty/Brainy Templates Actions New Actions New New Actions Commands Views Services Resolvers Runmode
58. Controllers Models Smarty Templates Actions New Actions New New Actions Command s Views Services Resolvers Runmode
59. Controllers Models Smarty Templates Actions New Actions New New Actions Command s Views Services Resolvers Runmode
60. Controllers Models Smarty Templates Actions New Actions New New Actions Command s Views Services Resolvers Runmode
61. Controllers Models Smarty/Brainy Templates Actions New Actions New New Actions Commands Views Services Resolvers Runmode
62. Controllers Models Actions New Actions New New Actions Commands Views Services Resolvers Runmode Smarty/Brainy Templates Webapp Controller Webapp DataProvider
63. Controllers Models Actions New Actions New New Actions Commands Views Services Resolvers Runmode Smarty/Brainy Templates Webapp Controller Webapp DataProvider
64. Unclear Ownership
69. Deployment Problems
70. Build Test Deploy
71. Build Test Deploy
72. Build Test Deploy
73. Build Test Deploy
74. Build Test Deploy
75. Build Test Deploy
76. Build Test Deploy
81. 10% 10% 10% Deploy 72% Chance Of Success
82. 10% 10% 10% Deploy 53% Chance Of Success 10% 10% 10%
83. 10% 10% 10% Deploy 28% Chance Of Success 10% 10% 10% 10% 10% 10% 10% 10% 10%
84. Deploy 1% Chance Of Success
85. Deploy
86. Deploy
87. Deploy
88. Deploy
89. Challenges of Splitting a Monolith
91. Original Code Tangled
93. Entirely Separate Talk
94. Trying to Replicate Functionality
95. Entirely New Infrastructure
96. Entirely New Infrastructure
97. RISKY
98. So, how can we mitigate the risks?
99. Using Feature Flags to Split a Monolith
100. Minimize Move
101. Remove Dead Code
102. Why is your code dead? Method no longer referenced Parameter never has certain values Endpoint never called
104. log.info(“CODE NOT DEAD UID: 12345”);
106. private void logForCleanup(String orgId, String uid) { if (Treatments.ON .equals(_splitClient.getTreatment(orgId, Splits.CLEANUP.name()))) { String message = String.format(“CODE NOT DEAD UID: %s”, uid); log.info(message); } }
107. private void logForCleanup(String orgId, String uid) { if (Treatments.ON .equals(_splitClient.getTreatment(orgId, Splits.CLEANUP.name()))) { String message = String.format(“CODE NOT DEAD UID: %s”, uid); log.info(message); } } Turn on CLEANUP split to 1%
108. 1. Roll out to 1% 2. Remove any lines hit 3. Roll out to 5% 4. Remove any lines hit 5. Roll out to 100% (leave here as long as makes you comfortable) 6. Remove any code that hasn’t been hit
110. Requests Monolith logic
111. Requests Monolith logic Interface
112. Requests Monolith logic New Microservice Interface Interface
113. Requests Monolith logic New Microservice Interface Interface
114. Requests Monolith logic New Microservice Interface Interface
115. Stress Test Your New Systems
117. Requests Monolith logic New Microservice Mirrored Traffic
118. Requests New Microservice Mirrored Traffic Feature Flag Check Monolith logic
119. Requests New Microservice Mirrored Traffic Feature Flag Check Monolith logic
120. Requests New Microservice Mirrored Traffic Feature Flag Check Monolith logic
121. Requests New Microservice Mirrored Traffic Feature Flag Check Monolith logic
122. Verify Parity
123. Requests New Microservice Feature Flag Parity Check Monolith logic
124. Requests New Microservice Feature Flag Parity Check Monolith logic
125. Requests New Microservice Feature Flag Parity Check Monolith logic
126. Requests New Microservice Feature Flag Parity Check Monolith logic
127. Requests New Microservice Feature Flag Parity Check Monolith logic Log if different
128. Requests New Microservice Feature Flag Parity Check Monolith logic Log if different
129. Requests New Microservice Feature Flag Parity Check Monolith logic Log if different
130. Slowly Roll Over Traffic
131. Slowly Roll Over Traffic 1%
132. Slowly Roll Over Traffic Free Users
133. Slowly Roll Over Traffic Internal Users
134. Slowly Roll Over Traffic Test Traffic Only
135. Slowly Roll Over Traffic
136. • Treatments.OLD • Treatments.NEW • Treatments.BOTH • Treatments.PARITY Default OFF treatment
137. Requests New Microservice Monolith logic Treatments.OLD
138. Requests New Microservice Monolith logic Treatments.NEW
139. Requests New Microservice Mirrored Traffic Monolith logic Treatments.BOTH
140. Requests New Microservice Monolith logic Treatments.PARITY Parity Check
141. Summary • What are feature flags? • Why split a monolith? • Challenges of Splitting a Monolith • How can feature flags help? • Remove dead code • Load test • Parity check • Gradual roll out/kill switch
142. What Are Feature Flags? Joy Ebertz @jkebertz Thank You!