Splitting Your Monolith with Feature Flags: A Guided Tour

The version used Sept 1, 2021 for the SAP event.

Transcript

1. A Guided Tour Splitting Your Monolith with Feature Flags Joy Ebertz Sr Staff Engineer
2. Agenda • Why split a monolith? • Strategies for Splitting a Monolith • Challenges of Splitting a Monolith • What are feature flags? • How can feature flags help?
3. Why Should We Split a Monolith?
4. What do I mean by “Splitting a Monolith?”
11. Why Split a Monolith? Code Entanglement
17. Unclear Ownership
22. Deployment Problems
23. Build Test Deploy
24. Build Test Deploy
25. Build Test Deploy
26. Build Test Deploy
27. Build Test Deploy
28. Build Test Deploy
33. 10% 10% 10% Deploy 72% Chance Of Success
34. 10% 10% 10% Deploy 53% Chance Of Success 10% 10% 10%
35. 10% 10% 10% Deploy 28% Chance Of Success 10% 10% 10% 10% 10% 10% 10% 10% 10%
36. Deploy 1% Chance Of Success
37. Deploy
38. Deploy
39. Deploy
40. Deploy
41. Issue Remediation
42. Deploy
43. Strategies for Splitting a Monolith
44. Big Bang Pattern
45. Big Bang Pattern Old Application
46. Big Bang Pattern New Application Old Application
47. Big Bang Pattern New Application Old Application
48. Big Bang Pattern New Application Old Application
49. Big Bang Pattern Advantages • Easier to remove features • Less Transition State Work
50. Strangler Fig Pattern Martin Fowler
51. Strangler Fig Pattern Old Application
52. Strangler Fig Pattern Old Application
53. Strangler Fig Pattern Old Application
54. Strangler Fig Pattern Old Application
55. Strangler Fig Pattern Old Application New Application
56. Strangler Fig Pattern Advantages • Less Risk • Lower time to first benefit • Easier to sell
59. Where to Start
60. Service Map
61. Requests Monolith logic
62. Requests Monolith logic Interface
63. Requests Monolith logic New Microservice Interface Interface
64. Requests Monolith logic New Microservice Interface Interface
65. Requests Monolith logic New Microservice Interface Interface
66. What should my first service be?
67. First Services Edges
68. First Services BFF (Backend for Frontend) or Application Services
69. First Services BFF Application Service Application Service Application Service
70. First Services Problematic Functionality
71. First Services Infrastructure Services Authentication
72. First Services Infrastructure Services Authentication Event Bus
73. First Services Infrastructure Services Authorization Authentication Event Bus
74. First Services New Features
75. First Services Things Undergoing Major Changes
76. First Services • Low Dependencies • Backend for Frontend • Unusual usage patterns • Infrastructure Components • New Features • Major Remodels
77. Challenges of Splitting a Monolith
79. Original Code Tangled
81. Entirely Separate Talk
82. Trying to Replicate Functionality
83. Entirely New Infrastructure
84. Entirely New Infrastructure
85. RISKY
86. So, how can we mitigate the risks?
87. What Are Feature Flags?
88. Other Terms • Feature Toggle • Feature Flip • Feature Switch • Conditional Feature • Split
89. Code Branch Controlled by GUI
90. Code Sample if (Treatments.ON .equals(_splitClient.getTreatment(orgId, Splits.MY_FEATURE.name()))) { // Do Something } else { // Do Something Else }
92. Code Sample if (Treatments.ON.equals(_splitClient.getTreatment(orgId, Splits.MY_FEATURE.splitName()))) { // Do Something } else { // Do Something Else }
93. Main Use-Cases
94. Main Use-Cases • Releasing features
95. Main Use-Cases • Releasing features • Production Testing
96. Main Use-Cases • Releasing features • Production Testing • A/B/C Testing
97. Main Use-Cases • Releasing features • Production Testing • A/B/C Testing • Custom Packages
98. Main Use-Cases • Releasing features • Production Testing • A/B/C Testing • Custom Packages • Temporary UI Customization
99. Main Use-Cases • Releasing features • Production Testing • A/B/C Testing • Custom Packages • Temporary UI Customization
100. Releasing Features • Separating Deploy from Release • Canary/Ramped Deployment • Off Switch
101. Deploy Release
102. </>
103. </> User
104. Prod User
105. Prod User
106. Prod Developer
107. Prod Developer
108. Prod User
109. Prod User Split
110. Prod User Split OFF OFF
111. Prod User Split OFF
112. Prod User Split OFF
113. Prod Split Product Owner OFF
114. Prod Split Product Owner ON
115. Prod User Split ON
116. Prod User Split ON
117. Prod User Split ON
118. Prod User Split ON
119. Prod Developer
120. Prod Developer
121. Prod User Split 10%
122. Prod User Split 20%
125. Using Feature Flags to Split a Monolith
126. Minimize Move
127. Remove Dead Code
128. Why is your code dead?
129. Why is your code dead? Method no longer referenced
130. Why is your code dead? Method no longer referenced Endpoint never called
131. Why is your code dead? Method no longer referenced Parameter never has certain values Endpoint never called
133. log.info(“CODE NOT DEAD UID: 12345”);
135. 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); } }
136. 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%
137. 1. Roll out to 1%
138. 1. Roll out to 1% 2. Remove any lines hit
139. 1. Roll out to 1% 2. Remove any lines hit 3. Roll out to 5%
140. 1. Roll out to 1% 2. Remove any lines hit 3. Roll out to 5% 4. Remove any lines hit
141. 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)
142. 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
144. Stress Test Your New Systems
146. Requests Monolith logic New Microservice Mirrored Traffic
147. Requests New Microservice Mirrored Traffic Feature Flag Check Monolith logic
148. Requests New Microservice Mirrored Traffic Feature Flag Check Monolith logic
149. Requests New Microservice Mirrored Traffic Feature Flag Check Monolith logic
150. Verify Parity
151. Requests New Microservice Feature Flag Parity Check Monolith logic
152. Requests New Microservice Feature Flag Parity Check Monolith logic
153. Requests New Microservice Feature Flag Parity Check Monolith logic
154. Requests New Microservice Feature Flag Parity Check Monolith logic
155. Requests New Microservice Feature Flag Parity Check Monolith logic Log if different
156. Requests New Microservice Feature Flag Parity Check Monolith logic Log if different
157. Requests New Microservice Feature Flag Parity Check Monolith logic Log if different
158. • Treatments.OLD
159. • Treatments.OLD • Treatments.NEW
160. • Treatments.OLD • Treatments.NEW • Treatments.MIRROR
161. • Treatments.OLD • Treatments.NEW • Treatments.MIRROR • Treatments.PARITY
162. • Treatments.OLD • Treatments.NEW • Treatments.MIRROR • Treatments.PARITY Default OFF treatment
163. Requests New Microservice Monolith logic Treatments.OLD
164. Requests New Microservice Monolith logic Treatments.NEW
165. Requests New Microservice Mirrored Traffic Monolith logic Treatments.MIRROR
166. Requests New Microservice Monolith logic Treatments.PARITY Parity Check
167. Slowly Roll Over Traffic
168. Slowly Roll Over Traffic Test Traffic Only
169. Slowly Roll Over Traffic Internal Users
170. Slowly Roll Over Traffic 1%
171. Slowly Roll Over Traffic Free Users
172. Slowly Roll Over Traffic
173. Summary • Why split a monolith? • Strategies for Splitting a Monolith • Challenges of Splitting a Monolith • What are feature flags? • How can feature flags help? • Remove dead code • Load test • Parity check • Gradual roll out/kill switch
174. What Are Feature Flags? Joy Ebertz @jkebertz Thank You!