Practical Chaos Engineering: Breaking things on purpose to make them more resilient against failure

With the wide adoption of micro-services and large-scale distributed systems, architectures have grow increasingly complex and hard to understand. Worse, the software systems running them have become extremely difficult to debug and test, increasing the risk of outages. With these new challenges, new tools are required and since failures have become more and more chaotic in nature, we must turn to chaos engineering in order to reveal failures before they become outages. In this talk, we will first introduce chaos engineering and show the audience how to start practicing chaos engineering on the AWS cloud. We will walk through the tools and methods they can use to inject failures in their architecture in order to make them more resilient to failure.

Following the previous introduction to Chaos Engineering, in this hands on session, I will show the audience how to practically inject failures into software systems using a few different tools and methods - e.g using Gremlin, Chaos Toolkit, AWS System Manager, AWS Lambda, ToxiProxy, etc.

Transcript

1. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. Practical Chaos Engineering: Breaking things on purpose to make them more resilient against failure Adrian Hornsby Principal Evangelist Amazon Web Services
2. © 2019, 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. © 2019, 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???
5. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved.
6. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. GameDay at Amazon Creating Resiliency Through Destruction https://www.youtube.com/watch?v=zoz0ZjfrQ9s
7. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. Chaos Engineering https://github.com/Netflix/SimianArmy
8. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. Chaos engineering is NOT about breaking things randomly without a purpose, chaos engineering is about breaking things in a controlled environment and through well- planned experiments in order to build confidence in your application to withstand turbulent conditions.
9. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. Break your systems on purpose. Find out their weaknesses and fix them before they break when least expected.
10. S U M M I T © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. Chaos Engineering
11. Operations Infrastructure Application Software
12. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. https://aws.amazon.com/wellarchitected
13. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. https://medium.com/@adhorn
14. S U M M I T © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. Chaos Engineering
15. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. STEADY STATE HYPOTHESIS RUN EXPERIMENT VERIFY IMPROVE Phases of Chaos Engineering
16. © 2019, 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
17. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. What is steady state? • ”normal” behavior of your system • Business + Ops Metric https://medium.com/netflix-techblog/sps-the-pulse-of-netflix-streaming-ae4db0e05f8a
18. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. STEADY STATE HYPOTHESIS RUN EXPERIMENT VERIFY IMPROVE Phases of Chaos Engineering
19. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. 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!
20. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. STEADY STATE HYPOTHESIS RUN EXPERIMENT VERIFY IMPROVE Phases of Chaos Engineering
21. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. Failure injection • Start small & build confidence • Application level • Host level • Resource attacks (CPU, memory, …) • Network attacks (dependencies, latency, …) • AZ attack • Region attack • People attack
22. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. Benefits of Failure Injection - Practicing failure contingency. - Understanding of the effects of real world failures. - Understanding the efficacy of the fault tolerance mechanisms. - Removing designs faults in the fault tolerance mechanisms. - Understanding the effectiveness of your observability. - Understanding the blast-radius of failures and help reduce it. - Understanding the weak links in the design – especially single points of failures. - Understanding failure propagation between system component. Learn to avoid cascading effect. - …
23. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. Blast radius • How many customers? • What functionality? • How many locations?
24. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. Rules of thumbs Have an emergency STOP or a good exit plan! Careful with state that can’t be rolled back (corrupt or incorrect data)
25. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. STEADY STATE HYPOTHESIS RUN EXPERIMENT VERIFY IMPROVE Phases of Chaos Engineering
26. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. 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?
27. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. PostMortems – COE (Correction of Errors) The 5 WHYs Outage Because of … Because of … Because of … Because of …
28. © 2019, 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?
29. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. DON’T blame people!!!
30. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. Rules to remember! There is no isolated ‘cause’ of an accident.
31. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. STEADY STATE HYPOTHESIS RUN EXPERIMENT VERIFY IMPROVE Phases of Chaos Engineering
33. S U M M I T © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. How to do Failure Injection
34. S U M M I T © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. Start simple and local!! $ docker stop 94a214bbeebd
35. S U M M I T © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. Burn CPU with Stress(–ng) $ stress-ng --random 50 -t 60 --metrics-brief --times https://kernel.ubuntu.com/~cking/stress-ng/
36. S U M M I T © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. Adding delay to the network $ tc qdisc add dev eth0 root netem delay 200ms 40ms 25% loss 15.3% 25% duplicate 1% corrupt 0.1% reorder 25% 50%
37. S U M M I T © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. Blocks DNS resolution $ iptables -I OUTPUT -p udp -d <DNS server IP> --dport 53 -j DROP Get the DNS: $ cat /etc/resolv.conf search eu-west-1.compute.internal nameserver 172.31.0.2 $ dig showme.mynameserver.xyz
38. S U M M I T © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. How to DDoS yourself $ wrk -t12 -c400 -d30s http://127.0.0.1/api/health
39. S U M M I T © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. Other fun things to do • Fill up disk • Network packet loss (using traffic-shaping) • Network packet corruption (using traffic-shaping) • Kills random processes • Detach (force) all EBS volumes • Mess with /etc/hosts
40. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. https://github.com/Netflix/SimianArmy Set of scheduled agent: • shuts down services randomly • slows down performances • checks conformity • breaks an entire region • Integrates with spinnaker (CI/CD)
41. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. ToxiProxy • HTTP API • Build for Automated testing in mind • Not for production environment • Fast • Toxics for: • Timeouts, latency, connections and bandwidth limitation, etc.. • CLI • Stable and well tested (used for 3 years at Shopify) • Open Source: https://github.com/Shopify/toxiproxy
42. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. https://atscaleconference.com/videos/resiliency-testing-with-toxiproxy/
43. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. https://github.com/asobti/kube-monkey
44. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. Pumba https://github.com/alexei-led/pumba/
45. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. https://blog.thundra.io/chaos-test-your-lambda-functions-with-thundra
46. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. APIs J
47. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. Fault Injection Queries for Amazon Aurora SQL commands issued to simulate: • A crash of the master instance or an Aurora Replica • A failure of an Aurora Replica • A disk failure • Disk congestion https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/AuroraMySQL.Managing.FaultInjectionQueries.html
48. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. Fault Injection Queries for Amazon Aurora SQL commands issued to simulate: • A crash of the master instance or an Aurora Replica • A failure of an Aurora Replica • A disk failure • Disk congestion ALTER SYSTEM SIMULATE percentage_of_failure PERCENT DISK FAILURE [ IN DISK index | NODE index ] FOR INTERVAL quantity { YEAR | QUARTER | MONTH | WEEK | DAY | HOUR | MINUTE | SECOND };
49. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. ❯ aws lambda put-function-concurrency --function-name <value> -- reserved-concurrent-executions 0
50. Injecting Chaos to AWS Lambda $ pip install chaos-lambda
51. https://github.com/adhorn/aws-lambda-chaos-injection
52. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. The Chaos Toolkit • Simplifying Adoption of Chaos Engineering • An Open API to Chaos Engineering • Open source extensions for • Infrastructure/Platform Fault Injections • Application Fault Injections • Observability • Integrates easily into CI/CD pipelines
53. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved.
54. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved.
55. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved.
56. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved.
57. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. Injecting Chaos to Amazon EC2 using AWS System Manager https://medium.com/@adhorn/injecting-chaos-to-amazon-ec2-using-amazon-system-manager-ca95ee7878f5
58. https://github.com/adhorn/chaos-ssm-documents
59. SSM Run (send) Command $ aws ssm send-command --document-name "cpu-stress" --document-version "1" --targets '[{"Key":"InstanceIds","Values":[ " i-094c8367024633d96 ","i-04d0976f9fb658c23"]}]’ --parameters '{"duration":["60"],"cpu":["0"]}’ --timeout-seconds 600 --max-concurrency "50" --max-errors "0" --output-s3-bucket-name "adhorn-chaos-ssm-output" --region eu-west-1
60. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. Big challenges to chaos engineering • Chaos Engineering won’t make your system more robust, People will. • Chaos Engineering won’t replace __all__ the rest (test, quality, …) • Chaos Engineering is NOT the only way to learn from failure • Rollbacks are HARD because of state. • Your systems will continue to fail, sorry.
61. © 2019, 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.
62. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. Changing culture takes time! Be patient…
65. © 2019, Amazon Web Services, Inc. or its affiliates. All rights reserved. Thank you! Adrian Hornsby https://medium.com/@adhorn adhorn