Azure storage and CDN and getting blob

Question

I have problem with caching in CDN for Azure Storage. I have set up storage, add CDN on it, and put custom domain.

And all works fine, until recently, when one image I uploaded, get stuck on CDN. When I'm getting to it without CDN all works fine, but over CDN it always shown old image. I tried everything, I put custom cache expiration, I deleted, I moved it... But nothing works. And I waited for one day, maybe will fix by Auzura automatically, or some caching will expiry, but nothing.

Does anybody had similar problem before? How to fix it?

All other images (blobs) in same container works fine.

Answer 1

You have to be really careful when planning the CDN usage. When you enable for CDN, you have to be in full control of all and any Blob files that will be served through the CDB.

This is by being explicit about setting x-ms-blob-cache-control property on a Put Blob, Put Block List, or Set Blob Properties request, or use the Azure Managed Library to set the BlobProperties.CacheControl property.

In case you forgot to set this property before the file was accessed by the CDN, the CDN assumes 7 days as TTL (Time-to-live for that file). Any consequent change of the settings (cache-control property of the blob) will not take effect until after the 7 days TTL elapses. I believe you have accidentally entered into this default 7 days TTL (hoping it is not the worst - wrongly set cache-expire header with a longer period)

You can read more on best practices for controlling CDN content here. And I warmly ask you to give your 3 votes at this feature request.