TDC Floripa 2016 - Elixir in production: The experience at Xerpa

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ELIXIR IN PRODUCTION: THE EXPERIENCE AT XERPA Renan Ranelli

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Milhouse (@renanranelli)

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Software Engineer @ Milhouse (@renanranelli)

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(former) Software Engineer @ Milhouse (@renanranelli)

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Milhouse (@renanranelli)

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AGENDA • Why the heck are people talking so much about FP ? • What the heck is “Xerpa” ? • What the heck is “Elixir” ? • A little bit about our experience and main struggles. • Discussion, questions and things like that.

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WHAT'S HAPPENING ON HARDWARELAND • You must google “no more free lunch”. • The takeaway is: – CPUs are not getting faster for single threaded applications. – Concurrency is the next major revolution in how we write software

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This was written in March 2005.

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2005

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In 2005: – Java 5 was hot news. – Windows XP. Vista only in 2007. – No AWS, Twitter, Netflix. – Ruby on Rails launching in December. – Youtube was just founded. – You've never heard of Justin Bieber

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This was written in March 2005

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FUNCTIONAL PROGRAMMING (!)

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FUNCTIONAL PROGRAMMING • Every* language built after that has concurrency as a main concern to be adressed – Scala, Clojure. – Elixir. – Go, Rust. – Erlang & Haskell's rediscovery. – Kotlin, Nim, Pony, Crystal, etc...

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FUNCTIONAL PROGRAMMING • Actually, functional programming is a very old paradigm (even older than OOP): – 1960 → Lisp – 1973 → ML – 1980s → Lazy langs: Miranda, KRC, SASL, Orwell... – 1986 → Erlang – 1990 → Haskell 1.0

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https://www.youtube.com/watch?v=njAMVB02Ag0 https://www.youtube.com/watch?v=kiaZd8dmbtI THERES LIFE BEYOND OOP IF YOU WANT TO KNOW MORE, I HAVE TWO TALKS FOR YOU

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ELIXIR @ XERPA

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ELIXIR @ XERPA

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• Our tech-stack today is something like this: – Elixir backend (!!) [Phoenix] – Clojurescript frontend (!!!!!) [Reagent/React] – Postgresql 9.4, (Cassandra soon) – ElasticSearch, Redis, C#/Mono (!?) – InfluxDB, Sensu & Grafana – Jenkins, Mailgun, Ansible, Terraform, AWS and *a lot* of shell scripting :D – No Docker, microservices, no service discovery.

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• Elixir in production for 7 months: 2k commits, 300 PRs, +- 21k lines of code, 4 devs ~ 150 modules

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• Elixir – Based on the Erlang VM. Can handle a lot of punching. – Erlang's runtime is extremely mature and battle-hardened. – Fault tolerance is a first class citizen. Hot-code reloads are possible. Many versions of the same module can coexist. – Erlang is built to yield uptimes up to 99.9999999% (really) – Communication is “shared nothing” and “default asynchronous”. – This is also called the “Actor System”.

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WHAT ELIXIR DOES REALLY WELL? • Everything is immutable. • There is a compiler (!). • Elixir is pragmatic (!!!) • Performance is great. GC is per-process. (*) • Documentation & tooling are take seriously. (*) • Macros. (*) • The runtime & OTP are AWESOME. Every process is preempted. No bad neighbors.

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PHOENIX >> RAILS • Where Phoenix excels over Rails ? – SUPER DUPPER FAST (!?) – Much easier to setup for high concurrency – Much less magic. Mostly everything is based on simple function calls. – Channels (!) – Views vs Templates. – It feels like “Rails done right”.

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Now to the not-fun part.

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PROBLEMS WE ENCOUNTERED SO FAR • The ecosystem is still very small (and somewhat buggy). – No options for monitoring apps (like new relic, appsignal, honeybadger). – Nothing as mature as Sidekiq (we have Exq and verk, but still...). – ExMachina (elixir's factory girl) is so broken. Ecto 2.0 will solve this. – No Monads. (we don't actually need them.)

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PROBLEMS WE ENCOUNTERED SO FAR • The ecosystem is still very small (and buggy). – No usable client for elastic search (*) – No usable (at the time?) library for exposing jsonapi (*) – No usable (at the time) library to handle auth (*) – No usable bindings for GraphicsMagick (*) – Releases are so damn hard and un-12factor (*) – Hot code reloads are much much harder than people say – Almost no problems with core libs like Ecto, Plug & Phoenix though.