Exposing Configuration Handling for Proxy Host and Port in WebAppUtils

The method getProxyHostAndPort is responsible for retrieving the proxy host and port from the YARN configuration. If the parameter yarn.web-proxy.address is not set or is empty, the system falls back to resolving the ResourceManager (RM) Web App URL without the scheme. However, this fallback mechanism can cause issues if the proxy settings are expected but not properly configured. The current implementation does not provide any logs or warnings when this fallback occurs, leading to potential misconfigurations going unnoticed.
 
Expected Behavior:
The system should log a warning when the yarn.web-proxy.address parameter is not set or is empty, informing the user that the system is falling back to the resolved RM Web App URL without the scheme. This log would help users identify and correct potential misconfigurations in their YARN proxy settings.
 
How-to-Fix:
We propose adding log statements to expose the handling of unset or empty configuration values when retrieving the proxy host and port.