OTP Labs

OTP Labs is a demo application built with Elixir and OTP to show how to integrate Distributed Elixir on Kubernetes with Horde and LibCluster.

This project ties up:

• Elixir Application with:
  • Libcluster Supervisor.
  • Horde Supervisor and Registry.
  • Node Observer. GenServer that make Horde Cluster update when node goes up or down.
• Libcluster config:
  • You can choose libcluster strategy(gossip or local epmd) from environment var.
  • You can add more libcluster strategies.
• Dockerfile:
  • Create an app image using linux alphine.
• Kubernete Deployment and Service file:
  • Deployment file:
    • Creates pods with app image, exports pod_ip, namespace and cluster_strategy (default: gossip).
    • Exports epmd port.
  • Service file:
    • Creates a cluster.
    • Exports empd port to all nodes.
• Elixir Release config:
  • Project sname configured using the following pattern @release.name@POD_A_RECORD.$NAMESPACE.pod.cluster.local.
• Makefile with tasks:
  • Run locally single-node.
  • Run locally multi-node.
  • Build docker image.
  • Run locally on docker.
  • Load docker image on minikube.
  • Create deployment and service on minikube
  • Remove docker image from docker, remove deployment and services from minikube

Setup local environment on Ubuntu

There is ansible recipe that helps setup local environment.

First, you should intall ansible ;)

$ sudo apt update
$ sudo apt install software-properties-common
$ sudo add-apt-repository --yes --update ppa:ansible/ansible
$ sudo apt install ansible -v 2.9.6

Use this setup in your project

Create a project with all this things using otp-labs project template.

Real world example

The distributed application meal planner called Umamify

References

• https://david-delassus.medium.com/elixir-and-kubernetes-a-love-story-721cc6a5c7d5
• https://mbuffa.github.io/tips/20201022-elixir-clustering-on-kubernetes/
• https://engineering.dollarshaveclub.com/elixir-otp-applications-on-kubernetes-9944636b8609
• https://learnyousomeerlang.com/what-is-otp
• https://moosecode.nl/blog/introducing_horde
• https://hexdocs.pm/horde/getting_started.
• https://staknine.com/elixir-config-environment-variables/
• https://hexdocs.pm/libcluster/readme.html
• https://firewalltimes.com/load-balancing-vs-server-clustering/
• https://ulisses.dev/elixir/2022/03/04/elixir-modules-files-directories-and-naming-conventions.html
• https://cve.mitre.org/cgi-bin/cvename.cgi?name=2020-24719
• https://samuelmullen.com/articles/elixir-processes-observability/
• https://codesync.global/media/observability-for-elixir-microservices-cbf20/
• https://github.com/erlef/observability-wg
• https://bigardone.dev/blog/2021/06/27/three-real-world-examples-of-distributed-elixir-pt-4
• https://www.freecodecamp.org/news/how-to-build-a-distributed-game-of-life-in-elixir-9152588100cd/
• https://elixirschool.com/en/lessons/storage/mnesia
• https://medium.com/wttj-tech/elixir-how-to-distribute-mnesia-between-multiple-nodes-cb7c851b1ed1
• https://github.com/meh/amnesia
• https://blog.appsignal.com/2020/05/19/using-mnesia-in-an-elixir-application.html
• https://medium.com/blackode/elixir-application-start-phases-6ef649845b44
• https://mbuffa.github.io/tips/20201111-elixir-troubleshooting-mnesia/
• https://elixirschool.com/en/lessons/basics/date_time
• https://www.faqcode4u.com/faq/228588/erlang-mnesia-equivalent-of-sql-select-from-where-field-in-value1-value2-valu
• https://runebook.dev/en/docs/erlang/lib/mnesia-4.19.1/doc/html/mnesia_chap3?page=3
• https://dashbit.co/blog/mix-hex-registry-build
• https://yos.io/2016/04/28/writing-and-publishing-elixir-libraries/
• https://rapidapi.com/blog/how-to-use-geodb-cities-api/
• https://www.youtube.com/watch?v=zUw_NY8LjTQ