Get props from OS system environment

[chrisjsimpson]

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: chrisjsimpson/obp-kubernetes#2 (comment) (<< 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

[chrisjsimpson]

Related:

https://cloud.docker.com/u/chrisjsimpson/repository/docker/chrisjsimpson/obpapi-kube/general