SpringOne Platform 2016 Speaker: Casey West; Principal Technologist, Pivotal This talk will use the seminal twelve-factor app essay as a guide to discuss the do’s and dont’s of building and running containers. Each factor gives us an opportunity to consider avoidable anti-patterns if you’re using containers to deploy and manage repeatable, reliable, and portable services. Containers rose in popularity on an oft used metaphor: lightweight virtual machines. We have a robust understanding of the benefits of virtualized hardware as a method of efficient resource utilization. The idea of even more efficient resource utilization makes sense. Unfortunately it’s a problematic metaphor. Containers represent a constrained set of capabilities compared to virtual machines in order to make fine-grained guarantees about resource constraints and process isolation. This is a good thing. There is overlap in ideal capabilities between VMs and containers but it isn’t complete. Newcomers to the container ecosystem begin with a “lightweight VM” understanding and fall victim to specific anti-patterns. After this talk you’ll understand common pitfalls in containerization and how you can avoid them. This discussion is useful for developers who wish to gain greater understanding of the environment their applications are deployed to, as well as operators interested in the benefits of containers for their architecture.

1. The Twelve-Factor
Container
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3. The Twelve-Factor Container
• Twitter @caseywest
• Email cwest@pivotal.io
• Web caseywest.com
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4. This isn't really a talk
about containers
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5. This is a talk about
operational maturity
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6. You must be this tall to
ride this ride
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7. Who has used…
• Containers?
• Schedulers?
• Cloud?
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8. Docker
Docker
Docker
Docker
Docker
Docker
Docker
Docker
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9. The factors
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10. 1: One codebase
tracked in revision
control, many deploys
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11. Anti-pattern
Building separate
images for staging and
production
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12. Anti-pattern
Tags for dev and prod
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13. Best Practice
Use the environment
and/or feature flags
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14. 2: Explicitly declare and
isolate dependencies
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15. 2: Explicitly declare and
isolate dependencies
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16. Anti-pattern
latest
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17. Best Practice
Declare version
numbers of upstream
dependencies
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18. Best Practice
Depend on base images
for default filesystem
and runtimes
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19. 3: Store config in the
environment
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20. Anti-pattern
config.yml
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21. Anti-pattern
properties.xml
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22. Anti-pattern
Hard-coded feature
flags
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23. Best Practice
This one is literally
about environment
variables
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24. Best Practice
This one is literally
about environment
variables ! ➡
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25. 4: Treat backing
services as attached
resources
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26. Anti-pattern
No local disk
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27. Anti-pattern
No local disk
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28. Anti-pattern
No local disk
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29. Best Practice
Connect to network-
attached services using
connection info from
the environment
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30. 5: Strictly separate
build and run stages
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31. Anti-pattern
Install on deploy
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32. Best Practice
Build immutable
images then run those
images
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33. Painfully Obvious Best Practices
Eat when hungry
Sleep when tired
Book Casey West for
speaking gigs
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34. Best Practice
Respect the lifecycle:
build, run, destroy
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35. 6: Execute the app as
one or more stateless
processes
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36. Best Practice
Schedule LRPs by
distributing them
across a cluster of
physical hardware
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37. Anti-pattern
NFS
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38. Anti-pattern
NFS
Need I say more?
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39. 7: Export services via
port binding
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40. Best Practice
port = Env.fetch(:PORT)
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41. Best Practice
my $port = $ENV{PORT};
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42. Best Practice
private String getPort() {
Map<String, String> env = System.getenv();
return env.get("PORT");
}
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43. Best Practice
let port = env::var("PORT").unwrap()
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44. 8: Scale out via the
process model
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45. Best Practice
Horizontally scale by
adding instances
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46. 9: Maximize robustness
with fast startup and
graceful shutdown
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47. 10: Keep development,
staging, and production
as similar as possible
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48. Best Practice
Run containers in
development
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49. 11: Treat logs as event
streams
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50. Anti-pattern
Random log files
#yolo'd all over the file
system
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51. Anti-pattern
Random log files
#yolo'd all over the file
system, bro
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52. Best Practice
STDOUT
STDOUT
STDOUT
STDOUT
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53. 12: Run admin/
management tasks as
one-off processes
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54. Anti-pattern
Custom containers for
tasks
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55. Best Practice
Reuse application
images with specific
entrypoints for tasks
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56. You are now cloud-native
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57. Repeatability
Reliability
Resiliency
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58. @caseywest
Let's be friends
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