container-common/src/main/java/com/streamsets/datacollector/security/SdcSecurityManager.java
private String replaceVariables(String path) {
    return path.replace("$SDC_DATA", dataDir)
      .replace("$SDC_CONF", configDir)
      .replace("$SDC_RESOURCES", resourcesDir)
      ;
  }
private String replaceVariables(String path) {
    return path.replace("$SDC_DATA", dataDir)
      .replace("$SDC_CONF", configDir)
      .replace("$SDC_RESOURCES", resourcesDir)
      ;
  }
Replace variables to internal SDC directories so that users don't have to be entering FQDN.