This document discusses developing a simple internal company website called Quote Pad using Elixir and Phoenix to learn the new technologies. The original version was built in 2012 using Ruby on Rails, but had issues like using SQLite in production and no moderation functionality. The new version uses Elixir, Phoenix, PostgreSQL, and improves the UI, adds moderation features, and migrates the existing data. The document outlines learning Elixir before Phoenix, common pitfalls to avoid like doing things in a non-Elixir way, and discusses deployment considerations like using Distillery and issues that can arise.

1. Playing with Elixir/Phoenix
Anton Sakharov, CTO @ MLSDev

4. Elixir / Phoenix

5. This talk is not about
Elixir syntax or Phoenix cool features

6. The best way to master new technology
or framework is
to develop something simple but
not useless
* IMHO

7. Internal company website: Quote Pad

8. ● Post quotes
● View quotes (latest / best)
● Vote for quotes (like / dislike)
● Email subscription to new quotes
Features

9. Old Quote Pad
● Written in 2012 by iOS developer in order to learn Ruby on Rails
● Rails 3.2.6
● SQLite in production ¯_(ツ)_/¯
● Email/password authentication using Devise gem
● Non-responsive UI
● No moderation functionality
● No admin area/dashboard

10. New Quote Pad
● Elixir/Phoenix
● Authentication via Google Apps / G Suite / whatever they name it tomorrow
● Amazon RDS / PostgreSQL
● UI facelift, make it responsive
● Moderation, admin. dashboard, blah-blah-blah...
● Migrate data/content

12. Learning curve
1. Elixir
2. Phoenix
3. Libraries
4. Deployment
5. …
6. PROFIT!!!

13. First steps
and things to avoid

14. Do not jump to Phoenix
straight away
Learn Elixir first

16. https://elixir-lang.org -> GUIDES

17. Do not learn Elixir and
Phoenix by tutorials and
videos only
1. You'll stay a Script Kiddie
2. Tutorials are probably outdated

19. This book is about Phoenix 1.2.
Current Phoenix is 1.3; 1.4 is about to be released

20. http://phoenixframework.org/

21. Before you go on ...

23. Must-read documentation
● Elixir guides (mentioned earlier)
● Phoenix guides and docs
● Plug (Rack / Middleware in Rails world)
● Ecto (ActiveRecord in Rails world)

24. https://hexdocs.pm

26. Pitfalls

27. ● Do Elixir stuff non-Elixir way
● Do Phoenix stuff Rails-way
● Tend to OOP
● Erlang OTP gives you a lot out of the box, keep it in mind
● On the other hand, there are not that many
production-ready packages yet (like RubyGems)
Pitfalls

28. Do Elixir stuff non-Elixir way
Non-Elixir:
list = Enum.map(1..100_000, &(&1 * 3))
list = Enum.filter(list, odd?)
list = Enum.sum(list)
Elixir:
list =
1..100_000
|> Enum.map(&(&1 * 3))
|> Enum.filter(odd?)
|> Enum.sum

29. Elixir:
def sum_list([head | tail], acc) do
sum_list(tail, head + acc)
end
def sum_list([], acc) do
acc
end
Non-Elixir:
sum = 0;
for (i=0; i<sizeof(array); i++)
sum += array[i]
Do Elixir stuff non-Elixir way

30. Do Phoenix stuff kind of Rails-way
defmodule User do
schema "users" do
# ...
field :quote_count, :integer, virtual: true
end
# ...
end
# …
def list_users(user, params) do
page = User |> Repo.paginate(params)
# Don't do this ;)
%{page | entries: Enum.map(page,
fn u -> %User{u | quote_count: Quotes.user_quote_count(u)} end)}
end

31. OOP habits
user.update(%{role: "admin"}) # this is not Elixir ;)
Users.update(user, %{role: "admin"}) # this is!

32. What about background jobs ?

34. Not too many production-ready stuff available yet
● from simple things like URL validators
● to advanced like Devise for Rails

35. Bodyguard

36. Authorize plug

37. Data migration
● dump SQLite database: `sqlite3 dbname.sqlite3 .dump > dump.sql`
● remove `AUTOINCREMENT`
● varchar(255) -> `CHARACTER VARYING(255)`
● datetime -> `TIMESTAMP WITHOUT TIME ZONE`
● ` (backtick) -> ' (single quote)
● '' (empty string) -> `NULL` for empty date/time
● ...

40. Deployment
● Distillery
● edeliver
● .env
● nginx in reverse proxy mode
● SSL certificate
● Docker
● AWS ECS
● …
● WAIT!

43. rel/config.exs

45. Deployment pitfalls
● Erlang binaries: Mac OS X vs Linux
● Erlang versions: brew vs apt-get

47. ● t2.micro (1 GB RAM) fails to build Erlang from source:
virtual memory exhausted
● it takes sooooo long to build Erlang from source…
Deployment pitfalls

48. DEMO

49. Links
https://elixir-lang.org/
http://www.phoenixframework.org/
https://github.com/h4cc/awesome-elixir/
https://hex.pm
https://hexdocs.pm/
https://github.com/mlsdev/

50. Any questions?

51. Thank you!