Automatic configuration decoding for Scala
val confideVersion = "0.0.3"
libraryDependencies ++= Seq(
"io.estatico" %% "confide-core" % confideVersion,
"io.estatico" %% "confide-macros" % confideVersion,
)To be able to use the @Conf macro, you'll need the Paradise compiler plugin.
addCompilerPlugin("org.scalamacros" % "paradise" % "2.1.0" cross CrossVersion.full),<properties>
...
<confide.version>0.0.3</confide.version>
</properties>
...
<dependencies>
...
<dependency>
<groupId>io.estatico</groupId>
<artifactId>confide-core_${scala.binaryVersion}</artifactId>
<version>${confide.version}</version>
</dependency>
<dependency>
<groupId>io.estatico</groupId>
<artifactId>confide-macros_${scala.binaryVersion}</artifactId>
<version>${confide.version}</version>
</dependency>
</dependencies>To be able to use the @Conf macro, you'll need the Paradise compiler plugin.
<pluginManagement>
...
<plugins>
<plugin>
<groupId>org.scala-tools</groupId>
<artifactId>maven-scala-plugin</artifactId>
<version>${scala.plugin.version}</version>
<configuration>
<compilerPlugins>
<compilerPlugin>
<groupId>org.scalamacros</groupId>
<artifactId>paradise_${scala.version}</artifactId>
<version>2.1.0</version>
</compilerPlugin>
</compilerPlugins>
</configuration>
</plugin>
</plugins>
</pluginManagement>Given the configuration file below -
api {
cache {
enable: true
ttl: 5m
}
greetings = ["Hello", "Hola", "Bonjour"]
}We can define the following Scala classes to automatically decode the config for us -
import io.estatico.confide._
@Conf final case class AppConfig(
api: ApiConf
)
@Conf final case class ApiConf(
cache: CacheConf,
greetings: List[String]
)
@Conf final case class CacheConf(
enable: Boolean,
ttl: FiniteDuration
)The case classes are pretty self-evident; they simply define the structure of the config we wish to decode.
The @Conf macro will derive an instance of FromConfObj for the annotated
case class. FromConf[A] and FromConfObj[A] are type classes which describes how to decode
config values to type A. Derivation leverages the wonderful
shapeless library.
All the @Conf macro does is inject an implicit FromConfObj.derive into the
case class' companion object.
scala> ConfideFactory.load[AppConfig]()
AppConfig(ApiConf(CacheConf(true,300000000000 nanoseconds),List(Hello, Hola, Bonjour)))
