How to read environment variables in Scala
ScalaEnvironment VariablesScala Problem Overview
In Java, reading environment variables is done with System.getenv().
Is there a way to do this in Scala?
Scala Solutions
Solution 1 - Scala
Since Scala 2.9 you can use sys.env for the same effect:
scala> sys.env("HOME")
res0: String = /home/paradigmatic
I think is nice to use the Scala API instead of Java. There are currently several project to compile Scala to other platforms than JVM (.NET, javascript, native, etc.) Reducing the dependencies on Java API, will make your code more portable.
Solution 2 - Scala
There is an object:
scala.util.Properties
this has a collection of methods that can be used to get environment info, including
scala.util.Properties.envOrElse("HOME", "/myhome" )
Solution 3 - Scala
Same way:
scala> System.getenv("HOME")
res0: java.lang.String = /Users/dhg
Solution 4 - Scala
Using directly a default with getOrElse over the sys.env Map (val myenv: Map[String, String] = sys.env):
sys.env.getOrElse(envVariable, defaultValue)
You get the content of the envVariable or, if it does not exist, the defaultValue.
Solution 5 - Scala
If Lightbend's configuration library is used (by default in Play2 and Akka) then you can use
foo = "default value" foo = ${?VAR_NAME}
syntax to override foo if an environment variable VAR_NAME exist. More details in https://github.com/typesafehub/config#optional-system-or-env-variable-overrides
Solution 6 - Scala
To print all environment variables, you can use
System.getenv.forEach((name, value) => println(s"$name: $value"))