ZIO learning - defining and injecting an effect based custom config layer into the environment / published by https://github.com/dacr/code-examples-manager #3cc42c59-4c46-4917-a37e-2df21f55027c/26359feba7e8e4e384f7266835a6794148966012

zio-learning-4-env-3-custom-3.sc

// summary : ZIO learning - defining and injecting an effect based custom config layer into the environment
// keywords : scala, zio, learning, pure-functional, @testable
// publish : gist
// authors : David Crosson
// license : Apache NON-AI License Version 2.0 (https://raw.githubusercontent.com/non-ai-licenses/non-ai-licenses/main/NON-AI-APACHE2)
// id : 3cc42c59-4c46-4917-a37e-2df21f55027c
// created-on : 2022-01-11T15:14:53+01:00
// managed-by : https://github.com/dacr/code-examples-manager
// run-with : scala-cli $file

// ---------------------
//> using scala  "3.2.2"
//> using dep "dev.zio::zio:2.0.13"
//> using dep "fr.janalyse::zio-worksheet:2.0.13.0"
// ---------------------

import zio.*, zio.worksheet.*

// -------------------------------------------------------------
case class AuthConfig(username: String, password: String)
case class Config(auth: AuthConfig)

val configLogic = for {
  username <- System.envOrElse("APP_USERNAME", "admin")
  password <- System.envOrElse("APP_PASSWORD", "admin")
  auth      = AuthConfig(username, password)
} yield Config(auth)
val configLayer = ZLayer(configLogic)
// -------------------------------------------------------------

val logic: ZIO[Config, Exception, Unit] = for {
  auth <- ZIO.environment[Config].map(_.get.auth)
  _    <- Console.printLine(s"Hello ${auth.username} !")
} yield ()

// -------------------------------------------------------------
logic.provideLayer(configLayer).unsafeRun