ConfigStringModule
Related Doc:
package config
Use functions in this Config object when you need to retrieve your instance of config in terms of zio.Layer.
Use functions in this Config object when you need to retrieve your instance of config in terms of zio.Layer.
For example:
final case class MyConfig(dburl: String, port: Int) val myConfigDesc: ConfigDescriptor[MyConfig] = (string("dburl") |@| int("port"))(MyConfig.apply, MyConfig.unapply) val myConfig: Layer[ReadError[String], Config[MyConfig]] = Config.fromSystemEnv(myConfigDesc)
By using Config.fromSystemEnv(myConfigDesc), it internally extends your description which is myConfigDesc to include the ConfigSource.
In the above example, it is the ConfigSource corresponding to sys.env.
It then calls zio.config.read with this new description that includes the source information.
Extending an existing config description to include a ConfigSource is as simple as
myConfigDesc from configSource
Also, note that Config[MyConfig] in the above example is a simple type alias to Has[MyConfig].
If you want to retrieve your config as scala.Either instead of zio.Layer, then you will have to extend
your description to include the information on ConfigSource manually.
For example:
import zio.config._, ConfigDescriptor._ final case class MyConfig(dburl: String, port: Int) val myConfig: ConfigDescriptor[MyConfig] = (string("dburl") |@| int("port"))(MyConfig.apply, MyConfig.unapply) val constantSource: ConfigSource = ConfigSource.fromMap(Map("dburl" -> "xyz", "port" -> "8080")) val result: Either[ReadError[String], MyConfig] = read(myConfig from constantSource)
Note: With the above approach, we got a simple scala.Either instead of retrieving them in terms of ZIO.
Instead of the above approach, if we use Config.fromMap(constantMap, myConfig),
then we will get a Layer[ReadError[String], MyConfig]
The above approach is especially useful when we have a custom ConfigSource.
For instance, we can form a custom ConfigSource by composing a few existing ConfigSources.
For example:
import zio.config._, ConfigDescriptor._ final case class MyConfig(dburl: String, port: Int) val myConfig: ConfigDescriptor[MyConfig] = (string("dburl") |@| int("port"))(MyConfig.apply, MyConfig.unapply) val sysEnvSource: UIO[MyConfig] = ConfigSource.fromSystemEnv val constantSource: ConfigSource = ConfigSource.fromMap(Map("dburl" -> "xyz", "port" -> "8080")) val result: IO[ReadError[String], MyConfig] = configSource.flatMap(source => read(myConfig from sysEnvSource.orElse(constantSource))
In the above example, the results returned an UIO because of the existence of ConfigSource corresponding to sys.env.
Generate documentation based on the ConfigDescriptor, where a
ConfigDescriptor is a structure representing the logic to fetch the application config
from various sources.
Generate documentation based on the ConfigDescriptor, where a
ConfigDescriptor is a structure representing the logic to fetch the application config
from various sources.
Generate a report based on the ConfigDescriptor and an A, where a
ConfigDescriptor represents the logic to fetch the application config
from various sources, and A represents the actual config value that was retrieved.
Generate a report based on the ConfigDescriptor and an A, where a
ConfigDescriptor represents the logic to fetch the application config
from various sources, and A represents the actual config value that was retrieved.