zio config examples with scala 3

-ZIOConfigExamples.scala

import com.typesafe.config.Config
import zio.*
import zio.config.ConfigDescriptor.*
import zio.config.ConfigSource.*
import zio.config.*
import zio.config.magnolia.Descriptor
import zio.config.typesafe.TypesafeConfigSource
import zio.cli.Args
import java.time.ZonedDateTime
import java.time.LocalDate
import scala.util.Try

// #region manual
package ManualFromApplicationAndReferenceConf {
  case class Human(name: String, age: Int)
  object App extends zio.ZIOAppDefault {
    val humanDescription =
      ((string("name") ?? "name of the human") zip (int("age") ?? "age of the human")).to[Human]
    val source = TypesafeConfigSource.fromResourcePath
    val desc   = humanDescription from source
    val data   = read(desc)

    override def run = for {
      d <- data
      _ <- Console.printLine(d)
    } yield ()
  }
}

// #endregion

// #region automatic
package AutomaticDerivation {
  case class Human(name: String, age: Int)
  val humanDescription = Descriptor[Human]
}

// #endregion

// #region fallback file
package FallbacConfFile {
  case class Human(name: String, age: Int, address: String)
  val humanDescription = Descriptor[Human]
  object App extends zio.ZIOAppDefault {
    val addressConf = ZIO.attempt(com.typesafe.config.ConfigFactory.parseResources("address.conf"))
    val source =
      TypesafeConfigSource.fromResourcePath <>
        TypesafeConfigSource.fromTypesafeConfig(addressConf)
    val desc = humanDescription from source
    val data = read(desc)
    override def run = {
      for {
        d <- data
        _ <- Console.printLine(d)
      } yield ()
    }
  }
}
// #endregion

// #region nested conf
package NestedConf {
  case class Kafka(topics: List[String])
  val description = Descriptor[Kafka]
  object App extends zio.ZIOAppDefault {
    val source = TypesafeConfigSource.fromResourcePath
    val desc   = nested("kafka")(description from (source))
    override def run = {
      for {
        data <- read(desc)
        _    <- Console.printLine(data)
      } yield ()
    }
  }
}
// #endregion

// #region case class custom
package CustomDecodedTypeConf {

  val hoconValue = """
  kafka = {
    topics = ["one", "two"]
    broker: "127.0.0.1:28000"
  }
  """
  case class Address(host: String, port: Int) {
    override def toString = s"$host:$port"
  }
  object Address {
    given Descriptor[Address] =
      Descriptor.from[Address](Descriptor[String].transformOrFailLeft(Address.parse)(_.toString))

    def parse(value: String): Either[String, Address] = value match {
      case s"$host:$port" if port.toIntOption.nonEmpty => Right(Address(host, port.toInt))
      case e                                           => Left(s"invalid address: $e")
    }
  }

  case class Kafka(topics: List[String], broker: Address)
  val descriptor: ConfigDescriptor[Kafka] = Descriptor[Kafka]

  object App extends zio.ZIOAppDefault {
    val source = TypesafeConfigSource.fromHoconString(hoconValue)
    val desc   = nested("kafka")(descriptor from source)
    override def run = {
      for {
        data <- read(desc)
        _ = assert(data == Kafka(List("one", "two"), Address("127.0.0.1", 28000)))
        _ <- Console.printLine(data)
      } yield ()
    }
  }
}

// #endregion

// #region opqaue type
package OpaqueCustomDecodedTypeConf {

  val hoconValue = """
  kafka = {
    topics = ["one", "two"]
  }
  """

  opaque type Topic = String
  given Descriptor[Topic] = Descriptor.from(ConfigDescriptor.string)

  case class Kafka(topics: List[Topic])
  val descriptor: ConfigDescriptor[Kafka] = Descriptor[Kafka]

  object App extends zio.ZIOAppDefault {
    val source = TypesafeConfigSource.fromHoconString(hoconValue)
    val desc   = nested("kafka")(descriptor from source)
    override def run = {
      for {
        data <- read(desc)
        _    <- Console.printLine(data)
      } yield ()
    }
  }
}
// #endregion

application.conf

name = "john"

kafka = {
  topics = ["one", "two"]
  broker = "127.0.0.1:27000"
}

reference.conf

address = "India"
age = 40