Kubernetes and elixir

Kubernetes and elixir

• 1.
  KUBERNETES AND ELIXIR JEFFREYCHAN ALEMBIC TWITTER: @JGMCHAN GITHUB: HTTPS://GITHUB.COM/JGMCHAN EMAIL: JGMCHAN@GMAIL.COM
• 2.
  WHAT IS KUBERNETES?
• 3.
  WHAT IS KUBERNETES?
• 4.
  "Kubernetes is aportable, extensible open-source platform for managing containerized workloads and services, that facilitates both declarative configuration and automation." 
 - Kubernetes Documentation
• 5.
  MY INTERPRETATION • Distributedplatform to run anything, as long as it's containers • Batteries included (networks, security, service discovery, secrets) • "Easier" to automate because you don't need to script
• 6.
  BASIC PLATFORM CONCEPTS •All applications are just some sort of task/worker (does things), workloads may be different • Needs to run on something (server, local desktop, etc.) • Usually needs to talk to other things through via network • Would be good if it's secure
• 7.
  THIS IS WHATKUBERNETES DOES • Takes care of all these things for us e.g. • What machine does the task run on? • How does each group of tasks find/talk to each other? • How does the clients talk to us? • How do I protect each workload?
• 8.
  ANOTHER POINT OFVIEW
• 9.
  DIGRESSION - DOCKER CONTAINERS •Different types of container like LXC, Solaris Zones, Rkt • Think of it as a packaging system for your app and all it's dependencies (including OS libraries), which also contains • hooks to run the application safely inside the package (container) • Not a Virtual Machine • Images are sharable through a "Docker Registry", e.g. [Dockerhub](https:// hub.docker.com/), [Google Container Engine (GKE)](https://cloud.google.com/ kubernetes-engine/) or your own internal registry. • This means I can build an image which anyone (or system) can pull down and run, provided they have Docker installed • In general, this means I can build and compile something locally, test it and push it up and be fairly sure it will work in other places
• 10.
  KUBERNETES CONCEPTS • Pods(e.g. Application Units) • Smallest Logical Unit (Usually 1 container per Pod) • Tasks/Worker containers (Does the work) • Controllers (A way to deploy the pods) • Deployments - Typical Service, long running replicated apps with multiple instances, Blue green • Jobs - These are just single tasks which runs to completion X number of times • Cronjobs - Tasks which run on schedule
• 11.
  KUBERNETES CONCEPTS -SERVICES, LOAD BALANCING AND NETWORKING • Quite complicated but the basic concepts are: • Services - an endpoint to sit in front of your workload to be accessed internally/externally • Ingress - Internal rules to control what can and cannot be accessed, e.g. paths/routes. Like NGINX configuration • DNS - A way to find other services in the cluster
• 12.
  KUBERNETES DEPLOYMENT CAN BEDECLARATIVE
• 13.
  BEAM VS KUBERNETES BEAMKubernetes Monitor Tasks ✅ ✅ Distributed across multiple nodes ✅ ✅ Service Discovery ✅ ✅ Hot Upgrades ✅ ❌ Language Agnostic ❌ ✅ Platform Components (networks) ❌ ✅
• 14.
  BEAM VS KUBERNETES •They are orthogonal, can co-exist peacefully • Kubernetes is focused on Day 2 and Enterprise Ops • BEAM is just awesome, but can be complicated and scary for Ops
• 15.
  KUBERNETES AND ELIXIR TOGETHER •Elixir Application needs to be inside a Docker container • Easier deployments • Good multi-tenancy • Treat Elixir App like any other app (task) • Environment variables for configs (REPLACE_OS_VARS=true) • Stateless is best
• 16.
  KUBERNETES AND ELIXIR- POSSIBLE DRAWBACKS • May not be able to use some BEAM goodies • No hot deployments • BEAM clustering can be messy (EPMD will have a hard time finding nodes) • No DETS • Kubernetes is great to use, super difficult to operate
• 17.
  CONCLUSION • Kubernetes andElixir can be great together • Treat your Elixir app like any other app, except it’s rock solid compared to other apps (e.g. Node.js) • Some drawbacks to be aware of • Kubernetes may not actually be necessary for your needs - Dev Experience vs Ops Pain