Emit Diagnostic Event for unsupported cross-stamp scaling settings #11396
Description
We've just had a CRI where a site was eligible for cross-stamp scaling but was using "files" as their secret store. This isn't supported because each stamp has it's own file system. This led to lots of random 401s being returned as each instance could potentially have it's own secrets, depending on the stamp.
We should be able to emit a diagnostic warning from the host if we detect:
- not using Azure Files -- meaning they are missing
WEBSITE_CONTENTAZUREFILECONNECTIONSTRINGandWEBSITE_CONTENTSHARE - using a url for
WEBSITE_RUN_FROM_PACKAGE - using "files" for
AzureWebJobsSecretStorageType - not using
WEBSITE_DISABLE_CROSS_STAMP_SCALE
It's a very confusing collection of settings that can cause issues and could be worth warning about when we detect it.