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Chaos Engineering

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Chaos Engineering

Chaos Engineering

  1. 1. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Adrian Hornsby Cloud Infrastructure – Amazon Web Services Chaos Engineering: Why Breaking Things Should Be Practiced. @adhorn
  2. 2. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Been there?
  3. 3. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Failures are a given and everything will eventually fail over time. Werner Vogels CTO – Amazon.com “ “
  4. 4. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. … at the Edge
  5. 5. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Building Confidence Through Testing Unit testing of components: • Tested in isolation to ensure function meets expectations. Functional testing of integrations: • Each execution path tested to assure expected results. Is it enough???
  6. 6. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Jesse Robbins GameDay: Creating Resiliency Through Destruction https://www.youtube.com/watch?v=zoz0ZjfrQ9s
  7. 7. Netflix 2013 https://medium.com/netflix-techblog
  8. 8. Chaos Monkeys https://github.com/Netflix/SimianArmy
  9. 9. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved. https://bit.ly/2uKOJMQ
  10. 10. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Twilio Use-Case Discovering Issues with HTTP/2 via Chaos Testing https://www.twilio.com/blog/2017/10/http2-issues.html ”While HTTP/2 provides for a number of improvements over HTTP/1.x, via Chaos Testing we discovered that there are situations where HTTP/2 will perform worse than HTTP/1.”
  11. 11. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. What “really” is Chaos Engineering?
  12. 12. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. “Chaos Engineering is the discipline of experimenting on a distributed system in order to build confidence in the system’s capability to withstand turbulent conditions in production.” http://principlesofchaos.org
  13. 13. Break your systems on purpose. Find out their weaknesses and fix them before they break when least expected.
  14. 14. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Failure Injection • Start small & build confidence • Application level • Host failure • Resource attacks (CPU, memory, …) • Network attacks (dependencies, latency, …) • Region attacks!
  15. 15. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. “CHAOS DOESN’T CAUSE PROBLEMS. IT REVEALS THEM.” Nora Jones Senior Chaos Engineer, Netflix
  16. 16. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Before breaking things …
  17. 17. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. People Application Network & Data Infrastructure
  18. 18. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Infrastructure
  19. 19. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Availability Availability Downtime per year 99% (2-nines) 3 days 15 hours 99.99% (4-nines) 52 minutes 99.999% (5-nines) 5 minutes 99.9999% (6-nines) 31 seconds
  20. 20. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. System Availability Availability = Normal Operation Time Total Time MTBF** MTBF** + MTTR* = * Mean Time To Repair (MTTR) **Mean Time Between Failure (MTBF)
  21. 21. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Availability in Parallel Component Availability Downtime X 99% (2-nines) 3 days 15 hours Two X in parallel 99.99% (4-nines) 52 minutes Three X in parallel 99.9999% (6-nines) 31 seconds
  22. 22. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Availability Zone 1 Availability Zone 2 Availability Zone n Multi-AZ Support Instance Failure Application
  23. 23. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Auto-Scaling • Compute efficiency • Node failure • Traffic spikes • Performance bugs
  24. 24. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Immutable Infrastructure • No updates on live systems • Always start from a new resource being provisioned • Deploy the new software • Test in different environments (dev, staging) • Deploy to prod (inactive) • Change references (DNS or Load Balancer) • Keep old version around (inactive) • Fast rollback if things go wrong
  25. 25. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Infrastructure as Code • Template of the infrastructure in code. • Version controlled infrastructure. • Repeatable template. • Testable infrastructure. • Automate it!
  26. 26. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Network & Data
  27. 27. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Read / Write Sharding RDS DB Instance Read Replica App Instance App Instance App Instance RDS DB Instance Master (Multi-AZ) RDS DB Instance Read Replica RDS DB Instance Read Replica
  28. 28. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Database Federation Users DB Products DB App Instance App Instance App Instance
  29. 29. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Database Sharding User ShardID 002345 A 002346 B 002347 C 002348 B 002349 A CBA App Instance App Instance App Instance
  30. 30. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Message passing for async. patterns A Queue B A Queue BListener Pub-Sub
  31. 31. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Web Instances Worker Instance Worker Instance Queue API Instance API Instance API Instance API: {DO foo} PUT JOB: {JobID: 0001, Task: DO foo} API: {JobID: 0001} GET JOB: {JobID: 0001, Task: DO foo} Cache Result: { JobID: 0001, Result: bar }
  32. 32. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Worker Instance Worker Instance Queue API Instance API Instance API Instance Cache Amazon SNS Push Notification User
  33. 33. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Exponential Backoff
  34. 34. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Circuit Breaker • Wrap a protected function call in a circuit breaker object, which monitors for failures. • If failures reach a certain threshold, the circuit breaker trips. https://martinfowler.com/bliki/CircuitBreaker.html
  35. 35. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Dynamic Routing with Route53 1. Latency Based Routing 2. Geo DNS 3. Weighted Round Robin 4. DNS Failover Amazon Route53 Resource A In US Resource B in EU User in US
  36. 36. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Dynamic Routing 1. Improve Latency for end-users 2. Disaster Recovery Applications in US West Applications in US East Users from San Francisco Users from New York Service 1 Service 2 Service 3 Service 4 Service 1 Service 2 Service 3 Service 4
  37. 37. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Application
  38. 38. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Stateless Services AZ1 AZ2 AWS Region Data Store Cache Auto-ScalingGroup User
  39. 39. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Transient state does not belong in the database.
  40. 40. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. CAP Theorem Consistency Availability Partition Tolerance Data is consistent. All nodes see the same state. Every request is non-failing. Service still responds as expected if some nodes crash. Distributed System In the presence of a network partition, you must choose between consistency and availability!
  41. 41. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Eventual Consistency … if no new updates are made to a given data item, eventually all accesses to that item will return the last updated value. Availability An eventually consistent system can return any value before it converges!! https://en.wikipedia.org/wiki/Eventual_consistency Distributed System Every request is non-failing.
  42. 42. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Process A Process B Process A Process B Synchronous Asynchronous Waiting Working Continues get or fetch resultGet result
  43. 43. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Non-blocking UI https://medium.com/@sophie_paxtonUX/stop-getting-in-my-way-non-blocking-ux-5cbbfe0f0158
  44. 44. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Exception Handling
  45. 45. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Service Degradation & Fallbacks
  46. 46. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. People
  47. 47. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. “It is not failure itself that holds you back; it is the fear of failure that paralyses you.” Brian Tracy
  48. 48. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Conway’s Law User UI Team Application Team DBA Team ”Any organization that designs a system (defined broadly) will produce a design whose structure is a copy of the organization's communication structure.” http://www.melconway.com/Home/Conways_Law.html Siloed Teams Siloed Applications
  49. 49. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Conway’s Law ”Any organization that designs a system (defined broadly) will produce a design whose structure is a copy of the organization's communication structure.” http://www.melconway.com/Home/Conways_Law.html Services Cross-Functional Teams
  50. 50. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Fire Drills
  51. 51. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Phases of Chaos Engineering
  52. 52. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Steady State Hypothesis Design Experiment Verify & Learn Fix
  53. 53. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. What is Steady State? • ”normal” behavior of your system https://www.elastic.co/blog/timelion-tutorial-from-zero-to-hero
  54. 54. What is Steady State? • ”normal” behavior of your system • Business Metric https://medium.com/netflix-techblog/sps-the-pulse-of-netflix-streaming-ae4db0e05f8a
  55. 55. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Business Metrics at work Amazon: 100 ms of extra load time caused a 1% drop in sales (Greg Linden). Google: 500 ms of extra load time caused 20% fewer searches (Marissa Mayer). Yahoo!: 400 ms of extra load time caused a 5–9% increase in the number of people who clicked “back” before the page even loaded (Nicole Sullivan).
  56. 56. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Steady State Important: • Know the value range of Healthy State!
  57. 57. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Hypothesis: What if…? “What if this load balancer breaks?” “What if Redis becomes slow?” “What if a host on Cassandra goes away?” ”What if latency increases by 300ms?” ”What if the database stops?” Make it everyone’s problem!
  58. 58. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Disclaimer! Don’t make an hypothesis that you know will break you!
  59. 59. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Designing Experiment • Pick hypothesis • Scope the experiment • Identify metrics • Notify the organization
  60. 60. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Rules of thumbs • Start with very small • As close as possible to production • Minimize the blast radius. • Have an emergency STOP!
  61. 61. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. New Version Users Run the Experiment: Canary deployment Old Version 99% Users 1% Users Start with .. Dynamic Routing (Route53)
  62. 62. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Verify & Learn: Quantifying the result of the experiment • Time to detect? • Time for notification? And escalation? • Time to public notification? • Time for graceful degradation to kick-in? • Time for self healing to happen? • Time to recovery – partial and full? • Time to all-clear and stable?
  63. 63. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. DON’T blame that one person …
  64. 64. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. PostMortems The 5 WHYs Outage Because of … Because of … Because of … Because of …
  65. 65. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. More questions to ask. • Can you clarify if there were any preceding events? • Why would they believe acting in this way was the best course of action to deliver the desired outcome? • Is there another failure mode that could present here? • What decisions or events prior to this made this work before? • Why stop there – are there places to dig deeper that could shine a light more on this? • Did others step in to help, to advise, or to intercede? http://willgallego.com/2018/04/02/no-seriously-root-cause-is-a-fallacy/
  66. 66. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Fixing the issues!
  67. 67. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Big Challenges to Chaos Engineering Mostly Cultural • no time or flexibility to simulate disasters. • teams already spending all of its time fixing things. • can be very political. • might force deep conversations. • deeply invested in a specific technical roadmap (micro-services) that chaos engineering tests show is not as resilient to failures as originally predicted.
  68. 68. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Changing Culture takes time! Be patient…
  69. 69. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. More Resources • https://mvdirona.com/jrh/talksAndPapers/JamesRH_Lisa.pdf • https://www.gremlin.com • https://queue.acm.org/detail.cfm?id=2353017 • https://softwareengineeringdaily.com/ • https://github.com/dastergon/awesome-sre • https://www.usenix.org/system/files/conference/osdi14/osdi14-paper-yuan.pdf • https://medium.com/@NetflixTechBlog • http://principlesofchaos.org • https://speakerdeck.com/tammybutow/chaos-engineering-bootcamp • https://github.com/adhorn/awesome-chaos-engineering • https://www.infoq.com/presentations/netflix-chaos-microservices • http://royal.pingdom.com/wp- content/uploads/2015/04/pingdom_uptime_cheat_sheet.pdf • http://willgallego.com/2018/04/02/no-seriously-root-cause-is-a-fallacy
  70. 70. © 2018, Amazon Web Services, Inc. or its affiliates. All rights reserved. Thank you! @adhorn https://medium.com/@adhorn

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