code: private void overrideFromEnvironmentVariables() {
          String  url = System.getenv("ACTIVEJDBC.URL");
          String  user = System.getenv("ACTIVEJDBC.USER");
          String  password = System.getenv("ACTIVEJDBC.PASSWORD");
          String  driver = System.getenv("ACTIVEJDBC.DRIVER");
          if(!blank(url) && !blank(user) && !blank(password) && !blank(driver)){
              connectionSpecMap.put(getEnvironment(), new ConnectionJdbcSpec(driver, url, user, password));
          }
  
          String  jndi = System.getenv("ACTIVEJDBC.JNDI");
          if(!blank(jndi)){
              connectionSpecMap.put(getEnvironment(), new ConnectionJndiSpec(jndi));
          }
      }
docs: Overrides current environment's connection spec from system properties.