Dr Sheldon Cooper Presents: Fun with Flags

No no, not country flags, feature flags! Feature flags are a powerful technique that allows teams to modify a system’s behaviour without changing code. They can be used several reasons – canary releases and A/B testing to name a few.

This talk will show you how you’re already using feature flags in your application without realising it. Next, we’ll take a look at some of the best tooling out there to help you take feature flags to the next level. Finally, we’ll cover strategies for removing feature flags before they become technical debt that you have to manage.

Transcript

2. Michael Heap
3. Don’t leave, pleeeaaaasseee
9. Fun with Country Flags! Presented by @mheap at #dpc18
10. Fun with Country Flags! Presented by @mheap at #dpc18
11. Fun with Country Flags! Presented by @mheap at #dpc18
12. Fun with Country Flags! Presented by @mheap at #dpc18
13. Fun with Feature Flags! Presented by @mheap at #dpc18
14. Michael @mheap Developer Relations NexmoDev
15. Fun with Feature Flags! Presented by @mheap at #dpc18
16. Today’s Plan
17. 1. What are feature flags? 2. Implementation 3. Flag management 4. Tips and tricks 5. Conclusion
18. 1. What are feature flags? 2. Implementation 3. Flag management 4. Tips and tricks 5. Conclusion
19. 1. What are feature flags? 2. Implementation 3. Flag management 4. Tips and tricks 5. Conclusion
20. 1. What are feature flags? 2. Implementation 3. Flag management 4. Tips and tricks 5. Conclusion
21. 1. What are feature flags? 2. Implementation 3. Flag management 4. Tips and tricks 5. Conclusion
22. Feature Flags?
23. Feature Toggles?
24. Feature Flip?
25. Feature Gate?
26. Feature Switches?
27. Separate feature release from code deployment
28. http://code.flickr.net/2009/12/02/flipping-out/
31. Feature flags aren’t new
32. #ifdef NEW_ALGORITHM NEW_ALGORITHM(input) #else ALGORITHM(input) #endif $ make build -DNEW_ALGORITHM
33. ./make_call.sh --use-new-algorithm ./make_call.sh --use-original-algorithm
34. if (in_array($user->id, $whitelistedUsers)) { return $service->useNewAlgorithm($input); } return $service->useAlgorithm($input);
35. I love a good history lesson
36. Use Cases?
37. 1. Permissions
38. 1. Permissions 2. Early-access
39. 1. Permissions 2. Early-access 3. Opt-in
40. 1. Permissions 2. Early-access 3. Opt-in 4. Incremental roll-out
41. 1. Permissions 2. Early-access 3. Opt-in 4. Incremental roll-out 5. Block users
42. 1. Permissions 2. Early-access 3. Opt-in 4. Incremental roll-out 5. Block users 6. Calendar driven
43. 1. Permissions 2. Early-access 3. Opt-in 4. Incremental roll-out 5. Block users 6. Calendar driven 7. Kill switch
44. 1. Permissions 2. Early-access 3. Opt-in 4. Incremental roll-out 5. Block users 6. Calendar driven 7. Kill switch 8. Power user
45. 1. Permissions 2. Early-access 3. Opt-in 4. Incremental roll-out 5. Block users 6. Calendar driven 7. Kill switch 8. Power user 9. Maintenance
46. 1. Permissions 2. Early-access 3. Opt-in 4. Incremental roll-out 5. Block users 6. Calendar driven 7. Kill switch 8. Power user 9. Maintenance 10. Sunset
48. Flag Types
49. Release Toggles Ops Toggles Flag Classes Permission Toggles Experiment Toggles
50. Release Toggles Ops Toggles Flag Classes Permission Toggles Experiment Toggles Lifetime Days Dynamism Per deployment
51. Release Toggles Ops Toggles Flag Classes Permission Toggles Experiment Toggles Lifetime Days - Weeks Dynamism Human Controlled
52. Release Toggles Ops Toggles Flag Classes Permission Toggles Experiment Toggles Lifetime Years Dynamism Per Request
53. Release Toggles Ops Toggles Flag Classes Permission Toggles Experiment Toggles Lifetime Weeks - Months Dynamism Per Request
54. https://martinfowler.com/articles/feature-toggles.html
55. Ownership Release toggles owned by devs Ops toggles owned by ops Permission toggles Experiment toggles owned by product
57. Flag Granularity
58. On/Off Switch Enable or disable entirely
59. On/Off Switch Percentage of users Enable or disable entirely Toggle for a percentage of users
60. On/Off Switch Percentage of users Individuals Enable or disable entirely Toggle for a percentage of users Toggle for specific users
61. On/Off Switch Percentage of users Individuals Groups Enable or disable entirely Toggle for a percentage of users Toggle for specific users Enable for specific groups e.g. Power Users
62. On/Off Switch Percentage of users Individuals Groups Request information Enable or disable entirely Toggle for a percentage of users Toggle for specific users Enable for specific groups e.g. Power Users Enable for specific request headers or bodies
64. Implementation
65. Build vs Buy
66. 1. Dashboard
67. 1. Dashboard 2. Access control
68. 1. Dashboard 2. Access control 3. Complex rules
69. 1. Dashboard 2. Access control 3. Complex rules 4. Cascading flags
70. 1. Dashboard 2. Access control 3. Complex rules 4. Cascading flags 5. Multivariate rules
71. 1. Dashboard 2. Access control 3. Complex rules 4. Cascading flags 5. Multivariate rules 6. Auditing
72. 1. Dashboard 2. Access control 3. Complex rules 4. Cascading flags 5. Multivariate rules 6. Auditing 7. Speed
73. 1. Dashboard 2. Access control 3. Complex rules 4. Cascading flags 5. Multivariate rules 6. Auditing 7. Speed 8. Scale
74. 1. Dashboard 2. Access control 3. Complex rules 4. Cascading flags 5. Multivariate rules 6. Auditing 7. Speed 8. Scale 9. 100% uptime
75. Build
76. Qandidate Toggle $manager = new ToggleManager(new InMemoryCollection()); $afterSix = new GreaterThanEqual(18); $beforeTen = new LessThanEqual(22); $conditions = []; $conditions[] = new OperatorCondition('time', $afterSix); $conditions[] = new OperatorCondition('time', $beforeTen); $toggle = new Toggle('disable-work-email', $conditions, Toggle::STRATEGY_UNANIMOUS); $manager->add($toggle); $context = new Context(); $context->set('time', (int) date('G')); echo 'Everyone is ' . ($manager->active('disable-work-email', $context)) ? ‘happy!' : 'sad :(';
77. Qandidate Toggle $manager = new ToggleManager(new InMemoryCollection()); $afterSix = new GreaterThanEqual(18); $beforeTen = new LessThanEqual(22); $conditions = []; $conditions[] = new OperatorCondition('time', $afterSix); $conditions[] = new OperatorCondition('time', $beforeTen); $toggle = new Toggle('disable-work-email', $conditions, Toggle::STRATEGY_UNANIMOUS); $manager->add($toggle); $context = new Context(); $context->set('time', (int) date('G')); echo 'Everyone is ' . ($manager->active('disable-work-email', $context)) ? ‘happy!' : 'sad :(';
78. Qandidate Toggle $manager = new ToggleManager(new InMemoryCollection()); $afterSix = new GreaterThanEqual(18); $beforeTen = new LessThanEqual(22); $conditions = []; $conditions[] = new OperatorCondition('time', $afterSix); $conditions[] = new OperatorCondition('time', $beforeTen); $toggle = new Toggle('disable-work-email', $conditions, Toggle::STRATEGY_UNANIMOUS); $manager->add($toggle); $context = new Context(); $context->set('time', (int) date('G')); echo 'Everyone is ' . ($manager->active('disable-work-email', $context)) ? ‘happy!' : 'sad :(';
79. Qandidate Toggle $manager = new ToggleManager(new InMemoryCollection()); $afterSix = new GreaterThanEqual(18); $beforeTen = new LessThanEqual(22); $conditions = []; $conditions[] = new OperatorCondition('time', $afterSix); $conditions[] = new OperatorCondition('time', $beforeTen); $toggle = new Toggle('disable-work-email', $conditions, Toggle::STRATEGY_UNANIMOUS); $manager->add($toggle); $context = new Context(); $context->set('time', (int) date('G')); echo 'Everyone is ' . ($manager->active('disable-work-email', $context)) ? ‘happy!' : 'sad :(';
80. Qandidate Toggle $manager = new ToggleManager(new InMemoryCollection()); $afterSix = new GreaterThanEqual(18); $beforeTen = new LessThanEqual(22); $conditions = []; $conditions[] = new OperatorCondition('time', $afterSix); $conditions[] = new OperatorCondition('time', $beforeTen); $toggle = new Toggle('disable-work-email', $conditions, Toggle::STRATEGY_AFFIRMATIVE); $manager->add($toggle); $context = new Context(); $context->set('time', (int) date('G')); echo 'Everyone is ' . ($manager->active('disable-work-email', $context)) ? ‘happy!' : 'sad :(';
81. Qandidate Toggle $manager = new ToggleManager(new InMemoryCollection()); $afterSix = new GreaterThanEqual(18); $beforeTen = new LessThanEqual(22); $conditions = []; $conditions[] = new OperatorCondition('time', $afterSix); $conditions[] = new OperatorCondition('time', $beforeTen); $toggle = new Toggle('disable-work-email', $conditions, Toggle::STRATEGY_MAJORITY); $manager->add($toggle); $context = new Context(); $context->set('time', (int) date('G')); echo 'Everyone is ' . ($manager->active('disable-work-email', $context)) ? ‘happy!' : 'sad :(';
82. Qandidate Toggle $manager = new ToggleManager(new InMemoryCollection()); $afterSix = new GreaterThanEqual(18); $beforeTen = new LessThanEqual(22); $conditions = []; $conditions[] = new OperatorCondition('time', $afterSix); $conditions[] = new OperatorCondition('time', $beforeTen); $toggle = new Toggle('disable-work-email', $conditions, Toggle::STRATEGY_AFFIRMATIVE); $manager->add($toggle); $context = new Context(); $context->set('time', (int) date('G')); echo 'Everyone is ' . ($manager->active('disable-work-email', $context)) ? ‘happy!' : 'sad :(';
83. Qandidate Toggle $manager = new ToggleManager(new InMemoryCollection()); $afterSix = new GreaterThanEqual(18); $beforeTen = new LessThanEqual(22); $conditions = []; $conditions[] = new OperatorCondition('time', $afterSix); $conditions[] = new OperatorCondition('time', $beforeTen); $toggle = new Toggle('disable-work-email', $conditions, Toggle::STRATEGY_UNANIMOUS); $manager->add($toggle); $context = new Context(); $context->set('time', (int) date('G')); echo 'Everyone is ' . ($manager->active('disable-work-email', $context)) ? ‘happy!' : 'sad :(';
84. Qandidate Toggle $manager = new ToggleManager(new InMemoryCollection()); $afterSix = new GreaterThanEqual(18); $beforeTen = new LessThanEqual(22); $conditions = []; $conditions[] = new OperatorCondition('time', $afterSix); $conditions[] = new OperatorCondition('time', $beforeTen); $toggle = new Toggle('disable-work-email', $conditions, Toggle::STRATEGY_UNANIMOUS); $manager->add($toggle); $context = new Context(); $context->set('time', (int) date('G')); echo 'Everyone is ' . ($manager->active('disable-work-email', $context)) ? ‘happy!' : 'sad :(';
85. Qandidate Toggle $manager = new ToggleManager(new InMemoryCollection()); $afterSix = new GreaterThanEqual(18); $beforeTen = new LessThanEqual(22); $conditions = []; $conditions[] = new OperatorCondition('time', $afterSix); $conditions[] = new OperatorCondition('time', $beforeTen); $toggle = new Toggle('disable-work-email', $conditions, Toggle::STRATEGY_UNANIMOUS); $manager->add($toggle); $context = new Context(); $context->set('time', (int) date('G')); echo 'Everyone is ' . ($manager->active('disable-work-email', $context)) ? ‘happy!' : 'sad :(';
86. $manager = new ToggleManager(new InMemoryCollection()); $afterSix = new GreaterThanEqual(18); $beforeTen = new LessThanEqual(22); $conditions = []; $conditions[] = new OperatorCondition('time', $afterSix); $conditions[] = new OperatorCondition('time', $beforeTen); $toggle = new Toggle('disable-work-email', $conditions); $manager->add($toggle); Configuration: Code
87. Configuration: Array $data = array( 'some-feature' => array( 'name' => 'toggling', 'conditions' => array( array( 'name' => 'operator-condition', 'key' => 'user_id', 'operator' => array('name' => 'greater-than', 'value' => 41), ), ), ), ); $serializer = new InMemoryCollectionSerializer(); $collection = $serializer->deserialize($data); $manager = new ToggleManager($collection);
88. Configuration: JSON/YAML $yaml = <<<YML toggles: - name: some-feature conditions: - name: operator-condition key: user_id operator: name: greater-than value: 41 YML; $array = Yaml::parse($yaml); $serializer = new InMemoryCollectionSerializer(); $collection = $serializer->deserialize($array); $manager = new ToggleManager($collection);
89. Configuration: Redis $predis = new Predis\Client(); $collection = new PredisCollection('toggle_demo', $predis); $manager = new ToggleManager($collection);
90. Qandidate Toggle API { "conditions" : [ { "name" : "operator-condition", "operator" : { "name" : "less-than", "value" : "1337" }, "key" : "user_id" } ], "name" : "foo", "status" : "conditionally-active", "originalName" : "foo" } PUT /toggles/{name} https://github.com/qandidate-labs/qandidate-toggle-api
91. Qandidate Toggle UI https://github.com/qandidate-labs/qandidate-toggle-ui
92. Build (Pros) 1. Free! 2. Total control 3. Complex rules 4. API and UI available
93. Build (Cons) 1. Self hosted 2. PHP only 3. Complex rules
94. Buy
96. Multi-Language
97. Prebuilt Dashboard
98. Environment Aware
99. Scaleable
100. Audit Log
101. A/B Testing
102. ld-relay
103. Buy (Pros) 1. Lovely dashboard 2. Multi-language 3. Built in audit log 4. Environment aware 5. A/B testing conversion tracking
104. Buy (Cons) 1. It costs (at least) $79/month 2. Can’t modify the product 3. Dependent on 3rd party
105. Build vs Buy
106. So. Much. Choice
107. It depends
108. Show me code
109. <?php use Qandidate\Bundle\ToggleBundle\Annotations\Toggle; /** * @Toggle("profile-management") */ class ProfileController { public function updatePassword() { } public function updateEmail() { } }
110. <?php use Qandidate\Bundle\ToggleBundle\Annotations\Toggle; class ProfileController { /** * @Toggle("profile-edit-password") */ public function updatePassword() { } public function updateEmail() { } }
111. public function onKernelRequest($event) { $flag = $event->getRequest->attributes->get('_flag'); $alt = $event->getRequest->attributes->get('_alt'); if ($toggleManager->active($flag, $context)) { $event->getRequest->attributes->set('controller', $alt); } } profile: path: /profile/{user} defaults: _controller: AcmeBundle:Profile:update _alt: AcmeBundle:NewProfile:update _flag: new-profile-controller
112. {% if feature_is_active('new-profile-image-picker') %} {# Show new picker #} {% else %} {# Use old flash-based picker #} {% endif %}
113. <?php class AudioProcessorFactory { public function build($args, $context) { if ($this->toggleManager->active(‘enhanced-audio', $context)) { return new EnhancedAudioStreamProcessor($args); } return new BasicAudioStreamProcessor($args); } }
114. Controller View Factory Enable a route for specific users Show different UI elements Branch by abstraction for refactoring
116. Toggle Configuratin
117. Hard Coded Change the code Dynamic Static
118. Hard Coded Deploy Config Change the code Deploy your application Dynamic Static
119. Hard Coded Deploy Config Parameterised Config Change the code Deploy your application Edit config, restart app Dynamic Static
120. Hard Coded Deploy Config Parameterised Config Database Config Change the code Deploy your application Edit config, restart app Edit via UI Dynamic Static
121. Hard Coded Deploy Config Parameterised Config Database Config Distributed Config Change the code Deploy your application Edit config, restart app Edit via UI e.g. Consul or Zookeeper Dynamic Static
122. Feature Dashboard
123. Flag State
124. Role Based Access
125. Audit Log
126. Non-technical Users
127. Technical Debt
128. DON’T
129. Cleanup based on activity
130. Cleanup based on activity
131. Create & Cleanup
132. WIP limits
133. Expiration date
134. Explosion date
135. Tips & Tricks
136. Testing Flags
137. Testing Flags Feature A Feature B ✅ ✅ ✅ ☠ ☠ ✅ ☠ ☠
138. Testing Flags Feature A Feature B Feature C ✅ ✅ ✅ ✅ ☠ ✅ ✅ ✅ ☠ ☠ ✅ ✅ ✅ ☠ ☠ ☠ ✅ ☠ ☠ ☠ ✅ ☠ ☠ ☠
139. Testing Flags Feature A Feature B Feature C Feature D ✅ ✅ ✅ ✅ ✅ ✅ ✅ ☠ ✅ ✅ ☠ ✅ ✅ ☠ ✅ ✅ ☠ ✅ ✅ ✅ ✅ ✅ ☠ ☠ ✅ ☠ ✅ ☠ ✅ ☠ ☠ ✅ ☠ ✅ ✅ ☠ ☠ ✅ ☠ ✅ ☠ ☠ ✅ ✅ ✅ ☠ ☠ ☠ ☠ ✅ ☠ ☠ ☠ ☠ ✅ ☠ ☠ ☠ ☠ ✅ ☠ ☠ ☠ ☠
140. Testing Flags Number of flags Possible permutations 2 4 3 8 4 16 5 32 10 1024 25 33,554,432 50 1.12589991E+15 100 1.2676506E+30
141. Homepage Carousel Homepage CTA ✅ ✅ ✅ ☠ ☠ ✅ ☠ ☠ Forum Edit Permission Forum Delete Permission ✅ ✅ ✅ ☠ ☠ ✅ ☠ ☠ Upload Profile Image ✅ ☠ New Interesting Algorithm ✅ ☠ High Post Length ✅ ☠ Show Debug Info? ✅ ☠ Enable Audit Log ✅ ☠ Auto Logout ✅ ☠ API Access API v2 ✅ ✅ ✅ ☠ ☠ ✅ ☠ ☠
142. Expose State { "api_v2": true, "audit_log": true, "new_recommendation_algo": false } GET /toggle_status
143. Flag Descriptions basic-rec-algo: true
144. Flag Descriptions basic-rec-algo: enabled: true description: Use a simplistic recommendation algorithm. This is fast and produces less load on backend systems, but is way less accurate than our standard algorithm.
145. Clear Naming allow_user_delete and allow_user_edit not user_control
146. Audit Log Feature State User Date allow_user_edit ✅ Sarah 2018-05-11 12:22:08 enhanced_rec_algo ✅ Ashley 2018-05-04 15:33:16 allow_user_signup ☠ Ashley 2018-05-04 15:27:33 enhanced_rec_algo ☠ system:load_manager 2018-05-04 15:16:30 allow_user_signup ✅ Bob 2018-05-04 15:12:01 enable_api ✅ Sarah 2018-04-30 09:56:59
147. Fail Safe Do positively enable features e.g. enable-ibm- analysis, enhanced-recomendation-algo Don’t use flags for suppressing new features e.g. disable-shiny-new-feature
148. Conclusion
149. Woooooooo
150. Flags are great!
151. Ops Toggles Release Toggles Flag Classes Permission Toggles Experiment Toggles
152. Build vs Buy
153. Qandidate Toggle
155. One More Thing
156. No Reuse
157. Knight Capital
158. High frequency trader
161. Mistakes were made
162. Knight Capital 1. Reused flags
163. Knight Capital 1. Reused flags 2. Didn’t delete obsolete code
164. Knight Capital 1. Reused flags 2. Didn’t delete obsolete code 3. Couldn’t be disabled without a deployment
165. Knight Capital 1. Reused flags 2. Didn’t delete obsolete code 3. Couldn’t be disabled without a deployment 4. The deploy actually enabled the old code on all 8 servers, instead of disabling it
166. $460m Gone
167. @mheap / @NexmoDev m@michaelheap.com https://joind.in/talk/253a0