How to ensure only one Azure Function BlobTrigger runs at a time?

Question

I have a use case to implement multiple BlobTriggers in Azure Functions (using the Linux Consumption Plan). For example in Azure Storage I would have 5 different clients with a directory structure like:

client1/file.txt  
client2.file.txt  
client3/file.txt  
client4/file.txt  
client5/file.txt

It's possible for both client1/file.txt and client2/file.txt to be dropped off at the same time in Azure Storage. To prevent race conditions and exceeding the 1.5 GB memory limit, I would like the BlobTrigger for client1/file.txt to wait for the BlobTrigger for client2/file.txt to finish or vice versa (the order doesn't matter here, just that both of them eventually execute).

Do I have to set up a queue process separately? Can I use the preview setting WEBSITE_MAX_DYNAMIC_APPLICATION_SCALE_OUTto achieve this easily?

Edit: Would using durable functions be a better solution?

Answer 1

You should be able to do this by making sure the MAX SCALE OUT value is set to 1, this way it will only process 1 file at a time. You can also change your consumption\pricing model from consumption to app service plan one. This way you can use the tier you want, then you can have more memory available as well (depending on the tier you choose).