I've configured Azure CDN (standard Microsoft profile/tier) over an Azure storage account to serve my static frontend website. I've added a custom domain to the Azure CDN endpoint, let's call this www.example.com. Now, let's assume the storage account is suddenly unavailable due to an outage in that region.
Questions
1. If the user hits www.example.com, would they be able to view the frontend website?
2. If the CDN endpoint caches the website, for how long would it serve the frontend website while the underlying storage account is down.
P.S.
I've read this answer to setup Azure front door but I'm trying to not modify the setup unless absolutely required.
If the user hits www.example.com, would they be able to view the frontend website?
Yes, users should be able to view the website because the content is cached by CDN. From this link:
An object that's already cached in Azure CDN remains cached until the time-to-live period for the object expires or until the endpoint is purged. When the time-to-live period expires, Azure CDN determines whether the CDN endpoint is still valid and the object is still anonymously accessible. If they are not, the object will no longer be cached.
If the CDN endpoint caches the website, for how long would it serve the frontend website while the underlying storage account is down.
That would depend on how you have configured the cache settings for the CDN. As long as the content is cached, CDN will not try to hit the source to get the new content. To learn more about caching and expiration, you may find this link useful: https://learn.microsoft.com/en-us/azure/cdn/cdn-manage-expiration-of-blob-content.