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