Net flix embracingfailure re-invent2014-141113085858-conversion-gate02
- 1. © 2014 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified, or distributed in whole or in part without the express consent of Amazon.com, Inc.
Embracing Failure
Fault Injection and Service Resilience at Netflix
Josh Evans – Director of Operations Engineering
Naresh Gopalani – Software Engineer and Architect
- 2. • ~50 million members, ~50 countries
• > 1 billion hours per month
• > 1000 device types
• 3 AWS Regions, hundreds of services
• Hundreds of thousands of requests/second
• CDN serves petabytes of data at terabits/second
Netflix Ecosystem
Service
Partners
Static
Content
Akamai
Netflix CDN
AWS/Netfli
x
Control
Plane
Internet
- 5. Failures can happen any time
• Disks fail
• Power outages
• Natural disasters
• Software bugs
• Human error
- 6. We design for failure
• Exception handling
• Fault tolerance and isolation
• Fall-backs and degraded experiences
• Auto-scaling clusters
• Redundancy
- 7. Testing for failure is hard
• Web-scale traffic
• Massive, changing data sets
• Complex interactions and request patterns
• Asynchronous, concurrent requests
• Complete and partial failure modes
Constant innovation and change
- 8. What if we regularly inject failures
into our systems under controlled
circumstances?
- 10. Blast Radius
• Unit of isolation
• Scope of an outage
• Scope a chaos exercise
Zone
Region
Instance
Global
- 12. Chaos Monkey
• Monkey loose in your DC
• Run during business hours
• What we learned
– Auto-replacement works
– State is problematic
- 13. A State of Xen - Chaos Monkey & Cassandra
Out of our 2700+ Cassandra nodes
• 218 rebooted
• 22 did not reboot successfully
• Automation replaced failed nodes
• 0 downtime due to reboot
- 15. Chaos Gorilla
Simulate an availability zone
outage
• 3-zone configuration
• Eliminate one zone
• Ensure that others can
handle the load and
nothing breaks
Chaos Gorilla
- 16. Challenges
• Rapidly shifting traffic
– LBs must expire connections quickly
– Lingering connections to caches must be addressed
• Service configuration
– Not all clusters auto-scaled or pinned
– Services not configured for cross-zone calls
– Mismatched timeouts – fallbacks prevented fail-over
- 18. AZ1 AZ2 AZ3
Regional Load Balancers
Zuul – Traffic Shaping/Routing
Data Data Data
Geo-located
Chaos Kong
Chaos Kong
AZ1 AZ2 AZ3
Regional Load Balancers
Zuul – Traffic Shaping/Routing
Data Data Data
Customer
Device
- 20. Challenges
● Service Configuration
○ Timeout configurations
○ Fallbacks fail or don’t provide the
desired experience
● No minimal (critical) stack
○ Any service may be critical!
- 22. Services Slow Down and Fail
Simulate latent/failed service
calls
• Inject arbitrary latency and errors at
the service level
• Observe for effects
Latency Monkey
- 24. Challenges
• Startup resiliency is an issue
• Services owners don’t know all dependencies
• Fallbacks can fail too
• Second order effects not easily tested
• Dependencies are in constant flux
• Latency Monkey tests function and scale
– Not a staged approach
– Lots of opt-outs
- 27. Distributed Systems Fail
● Complex interactions at scale
● Variability across services
● Byzantine failures
● Combinatorial complexity
- 29. Fault Injection Testing (FIT)
Device Service B
Service C
Internet Edge
Device or Account Override
Zuul
Service A
Request-level simulations
ELB
- 31. FIT Details
● Common Simulation Syntax
● Single Simulation Interface
● Transported via Http Request header
- 33. Failure Scenarios
● Set of injection points to fail
● Defined based on
○ Past outages
○ Specific dependency interactions
○ Whitelist of a set of critical services
○ Dynamic tracing of dependencies
- 34. FIT Insights : Salp
● Distributed tracing inspired by Dapper paper
● Provides insight into dependencies
● Helps define & visualize scenarios
- 35. Functional Validation
● Isolated synthetic transactions
○ Set of devices
Validation at Scale
● Dial up customer traffic - % based
● Simulation of full service failure
Dialing Up Failure
Chaos!
- 38. Take-aways
• Don’t wait for random failures
– Cause failure to validate resiliency
– Remove uncertainty by forcing failures regularly
– Better to fail at 2pm than 2am
• Test design assumptions by stressing them
Embrace Failure
- 39. The Simian Army is part of
the Netflix open source
cloud platform
http://netflix.github.com
- 40. Netflix talks at re:Invent
Talk Time Title
BDT-403 Wednesday, 2:15pm Next Generation Big Data Platform at Netflix
PFC-306 Wednesday, 3:30pm Performance Tuning EC2
DEV-309 Wednesday, 3:30pm From Asgard to Zuul, How Netflix’s proven Open Source
Tools can accelerate and scale your services
ARC-317 Wednesday, 4:30pm Maintaining a Resilient Front-Door at Massive Scale
PFC-304 Wednesday, 4:30pm Effective Inter-process Communications in the Cloud: The
Pros and Cons of Micro Services Architectures
ENT-209 Wednesday, 4:30pm Cloud Migration, Dev-Ops and Distributed Systems
APP-310 Friday 9:00am Scheduling using Apache Mesos in the Cloud
- 41. Please give us your feedback on this
presentation
© 2014 Amazon.com, Inc. and its affiliates. All rights reserved. May not be copied, modified, or distributed in whole or in part without the express consent of Amazon.com, Inc.
Join the conversation on Twitter with #reinvent
Josh Evans
jevans@netflix.com
@josh_evans_nflx
Naresh Gopalani
ngopalani@netflix.com