[ZEPPELIN-5465] "SERVICE_DOMAIN" may be null while Zeppelin server is running outside k8s

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 0.9.0
• Fix Version/s: 0.9.1, 0.10.0
• Component/s: Kubernetes
• Assignee: rickcheng
• Reporter: rickcheng
• Created: 21/Jul/21 09:59
• Updated: 02/Aug/21 03:54
• Resolved: 02/Aug/21 03:54

Description

The function `sparkUiWebUrlFromTemplate` needs to use the variable "SERVICE_DOMAIN", which is assigned to the default value of system environment variable "SERVICE_DOMAIN".

However, user may not set the environment variable when Zeppelin server is running outside of k8s, and it will get a NullPointerExcepetion:

NullPointerException: null value in entry: SERVICE_DOMAIN=null

Maybe it is better to set a non-null default value for it.