Get props from OS system environment

Objective:

Make container-like deployments easier by reading props from sys.env, we want to avoid rewriting the props file and repacking the war file like this: https://github.com/chrisjsimpson/obp-kubernetes/issues/2#issuecomment-460495439 (<< this is to be avoided)

For docker-like environments, it is helpful instead to read runtime settings from the operating system environment vars, because we can inject these at container runtime.

pseudo Logic

• Load props from system environment (sys.env) https://www.scala-lang.org/api/2.9.3/scala/sys/package.html
• Fallback to read from props file

pseudo code

  def getPropsValue(nameOfProperty: String): Box[String] = {
    # Replace "." with "_" (environment vars cannot include ".")
    brandSpecificPropertyName = brandSpecificPropertyName.replace('.', '_')
    # Convert to upper case
    brandSpecificPropertyName = brandSpecificPropertyName.toUpperCase()
    if (sys.env.get(brandSpecificPropertyName)) {
      
    } else {
      ..... load from props file as normal
    }
  }

Gotcha

• Environment variables will be upper case (s.toUpperCase())
• Environment variables cannot contain a dot ("."), therefore:
  • db.url becomes DB_URL
  • kafka.user.authentication becomes KAFKA_USER_AUTHENTICATION

Start by locating the property-loading implementation and the getPropsValue entry point described in the issue, then review how the existing props-file lookup works. Check how sys.env is accessed in the project and verify that normalized environment names take precedence while missing values fall back to the props file.