Multiple Azure function apps pointing to one Blob container(trigger)

The Function runtime/hosts(in each local environment) that run Azure Functions are isolated from each other, hence they both scan the incoming blobs and store receipts separately.

Internally, each host creates their own queue messages(incoming blob info) for Blob trigger to consume. My suggestion is to work with a centralized queue.

1. Send messages(blob name) to a queue when blobs are inserted using code. If we manually upload blobs using portal or Storage explorer, I suggest creating a Blob trigger with Queue output binding to send messages, note this trigger should run on only one host. Using blob trigger here is a bad solution as we actually retrieve blob twice, but it's the only way I can provide for manual upload.

   // v2 C# Blob Trigger sample for manual upload
   public static void Run([BlobTrigger("mycontainer/{name}")]Stream myBlob, 
       [Queue("myqueue")]out string message,
       string name, ILogger log)
   {
       log.LogInformation($"C# Blob trigger function Processed blob\n Name:{name}");
       message = name;
   }
   

2. Use Queue Trigger to consume messages from that queue, then get blob using Blob input binding. In this way we can ensure blob is retrieved once among all hosts.

   // v2 C# sample
   public static void Run([QueueTrigger("myqueue")]string blobName, ILogger log,
       [Blob("mycontainer/{queuetrigger}",FileAccess.Read)]Stream myBlob)
   {
       log.LogInformation($"C# Queue trigger function processed: {blobName}");
       log.LogInformation($"\n Size: {myBlob.Length} Bytes");
   }
   

If you use v1 function, there's another simple solution for local dev. With these settings, Blob Trigger in all hosts share the same internal queue and blob receipts.

1. In local.settings.json, make sure every Function project has the same value for AzureWebJobsStorage(where blob receipts, internal queue, etc. locate).
2. In host.json, add same id(use to construct the name of blob receipts and internal queue) for each host, e.g. "id":"localhost-1300897049".