I noticed a bit strange behavior of Blob Storage events during customer testing on Friday, and now I'm wondering if there are known situations which cause double events (blob created) to fire.
So basically an external application writes blobs to a container. Most of the blobs fire just one blob created event as usual, but for some reason, *.zip blobs (and only those) cause two event to fire close to one another ( < 0,5 secs apart). The zip file size is usually about 200-250 kB.
Earlier I have seen similar issues, but in those cases the first event always comes with
"contentLength": 0
...which also makes them very easy to filter out.
But in this scenario I'm getting two distinct events both with the same (and actual) blob size.
This might naturally be caused by the sender application too, I'm trying hard to get the correct people online to be able to verify and fix or possibly reproduce or issue with my own test code.
But is there a more detailed specification available that describes how those events are fired from blob storage. I'm also curious if there are any ways to avoid creating the 0-length event that sometimes seems to occur.
EDIT: Well - got finally the confirmation that this was actually a bug in the sending system, so we have no problem in this case. But still, if someone knows what actually triggers those possible "zero content length" events, that would also help planning future solutions.
