Configuration in Elixir

Small talk I held at the 50th Elixir UG Berlin on August 8, 2018.

* https://github.com/sashaafm/gcloudex/issues/4
* https://github.com/suitepad-gmbh/get_conf
* https://hexdocs.pm/get_conf/GetConf.html

Transcript

1. Lightning talk by Lukas Rieder @Elixir UG Berlin, August 9 2018
2. $ whoami
3. Lukas Rieder Freelance Consultant
4. I work for companies doing
 Infrastructure, ETL,
 Application development,
 HTTP Edge, Kubernetes
5. I work with Elixir
6. Configuration in Elixir
7. Do not: Store dynamic configuration use Mix.Config config :app_name, :config, System.get_env("CONFIG")
8. Do: Point to dynamic configuration using distillery REPLACE_OS_VARS use Mix.Config config :app_name, :config, "${CONFIG}"
9. Do not: Read configuration at compile time defmodule Foo do @config Application.get_env(:foo_app, :config) end
10. Do: Read configuration at runtime defmodule Foo do def config() do Application.get_env(:foo_app, :config) end end
11. Library configuration in Elixir
12. Stateless: Nothing to worry
13. Stateful: Provide Callback Modules
14. Stateful: Provide Callback Modules # init/1 Callback module MyPlug do def init(opts) do opts end end
15. Stateful: Allow User-modules and define otp_app
16. Stateful: Allow User-modules and define otp_app use Mix.Config config :config_app, ConfigApp.Repo,
 adapter: Ecto.Adapters.Postgres,
 # …
17. Stateful: Allow User-modules and define otp_app defmodule ConfigApp.Repo do use Ecto.Repo, otp_app: :config_app end
18. Stateful: Allow User-modules and define otp_app defmodule Ecto.Repo do defmacro __using__(opts) do quote bind_quoted: [opts: opts] do @otp_app opts[:otp_app]
 # … end end end
19. Stateful: Application libraries should be standard!
20. Configuration overwrites, inheritance?
21. use Mix.Config config :app_name, AppName, where: "elixir_ug", who: "lukas"
22. use Mix.Config config :app_name, AppName, where: "elixir_ug", who: "lukas"
 
 config :app_name, AppName.Conf, where: "elixir_conf"
23. GetConf.get_conf(:app_name, AppName, :where)
 # => "elixir_ug"
24. GetConf.get_conf(:app_name, AppName, :where)
 # => "elixir_ug"
 GetConf.get_conf(:app_name, AppName.Foo, :where)
 # => "elixir_conf"
25. GetConf.get_conf(:app_name, AppName, :where)
 # => "elixir_ug"
 GetConf.get_conf(:app_name, AppName.Foo, :where)
 # => "elixir_conf"
 GetConf.get_conf(:app_name, AppName.Foo, :who)
 # => "lukas"
26. defmodule AppName defmodule AppName.M1 defmodule AppName.M1.M2 Configuration lookup GetConf.get_conf/3
27. defmodule TestModule use GetConf, otp_app: :app_name def where(), do: get_conf(:where) end TestModule.where()
 # => "elixir_ug" 
 TestModule.get_conf(:where)
 # => "elixir_ug"
28. {:get_conf, "~> 0.1"} Thanks @ Suitepad GmbH
 @ Hildebrando Rueda
29. Upcoming: Flow Based Programming in Elixir {:get_conf, "~> 0.1"}
30. {:get_conf, "~> 0.1"} Thanks & enjoy.
31. {:get_conf, "~> 0.1"} Thanks & enjoy. Lightning talk by Lukas Rieder @Elixir UG Berlin, August 9 2018 l.rieder@gmail.com