Idiomatic Docker & K8s Deployments for Rails apps

Slides of talk at Bangalore Ruby User Group Meetup @ Clarisights, Bangalore - September, 2019.

Code for demo from: https://github.com/jamby1100/rails-docker-project

Update to the slide deck done on 18-Oct-2019.

1. Idiomatic Docker & K8s Deployments for Rails apps Ashwin aka @cruisemaniac
2. $whoami • Old school sys / network admin • <3 shell / UNIX • Cloud • IoT • Mail • DNS
3. Agenda • High-speed intro - Docker and K8s • Starting with development • Hitting Staging / UAT / Prod • Who’s around the place • Q & A
4. Docker / Kubernetes
5. Docker is a set of platform-as-a-service (PaaS) products that use OS-level virtualization to deliver software in packages called containers.
8. Kubernetes is a portable, extensible, open-source platform for managing containerized workloads and services, that facilitates both declarative configuration and automation.
9. Starting with development
10. Considerations • Dockerfiles • Docker-compose • Service segmentation • Design patterns
11. Dockerfiles
12. FROM ruby:2.5-alpine LABEL maintainer="Ashwin Murali <mail@cruisemaniac.com>" RUN apk update && apk add build-base nodejs postgresql-dev RUN mkdir /app WORKDIR /app COPY Gemfile Gemfile.lock ./ RUN bundle install COPY . . CMD puma -C config/puma.rb
13. YOUR CONTAINER IS A RUNTIME. IT IS NOT AN ECOSYSTEM!!!
14. Docker-compose
15. • Orchestrated Local development • Same as above, but mount volume using -v to /myapp
16. DO NOT USE UBUNTU:16.04
17. Work with alpine linux! It does everything you can think of!
18. Service segmentation
19. • Separate network-attached entity • Work with DNS. Not IP • Clarify separation of concerns • Understand multiple nodes per service
20. Design Patterns
21. • Sidecar • Ambassador • Adapter • Work Queue • Scatter / Gather
22. Scaling to Staging / Prod
23. Ideal scenario - Just go X * n
24. • Statelessness • Logging • Monitoring • Storage & Persistence
25. • No writing inside the container • Be as Read-Only as possible • ONE PROCESS PER CONTAINER
26. # config/application.rb L21 logger = ActiveSupport::Logger.new(STDOUT) Sidecar for centralised logging • ELK • Fluentd • Deliver config as env variables - use .env in dev
27. • Sidecar for monitoring • Integrate monitoring at multiple levels - Pod / Application / Service • Use monitoring responses to fail gracefully
28. Persistence is a problem!
29. Prefer managed services
30. PVs and PVCs • Flashy but hard problems • Reclaims, Deletes and Recycles are dangerous • Databases are scary to put on PVs
31. Providers
32. • GKE • EKS • AKS • Fargate • Vanilla
33. Post Mortem • High-speed intro - Docker and K8s • Starting with development • Hitting Staging / UAT / Prod • Who’s around the place • Q & A
34. Thank You!
35. Slides at https://speakerdeck.com/cruisemaniac