For the last 14 months, I've had an Azure Function running without issues. It uses a BlobTrigger to run whenever a new blob is created in a Blob Storage Container. Blobs are created very intermittently, so the Function almost exclusively relies on cold starts (latency is no concern). However, as of a weeks ago, the BlobTrigger no longer initiates a cold start (as in, 3 days later the Function still hadn't run). But when I access the Function in portal.azure to wake it up, BlobTrigger does fire once for each blob in the storage.
The interesting thing is that I haven't made any changes to this Function in at least 6+ months, so I'm struggling to identify the cause.
About the Azure Function:
- Consumption plan
- Runtime version 3.2.0.0
- Blob Storage trigger
- I deploy using Java/Maven
- Function code (Trigger)
@FunctionName("veninv")
public void blob(
@BlobTrigger(
name = "blob",
dataType = "binary",
path = "veninv-prod/{name}",
connection = "AzureWebJobsStorage")
byte[] content,
@BindingName("name") String blobname,
final ExecutionContext context
)
AzureWebJobsStorage is an application setting containing the connection string to a StorageV2 account.
Expected behaviour: When a new blob is created in the specified storage container, the Function's BlobTrigger initiates a cold start and wakes up the Function.
Actual behaviour: When a new blob is created, the Function's BlobTrigger doesn't initiate a cold start. Instead, the Function must be woken up manually in portal.azure after which the BlobTrigger will fire once for each blob.
Things I have done so far:
- "Diagnose and solve problems" shows no errors in my Function.
- I have confirmed the Function is set to a Consumption plan
- I restarted the Function App
- I have done an HTTP POST request to sync the trigger
- I enabled Scale Controller logging, which shows the following four logs after the Function last ran:
2021-10-14T20:35:11.0707779Z Adding or updating trigger. {"Category":"ScaleControllerLogs","AppName":"veninv-Prod","Timestamp":"2021-10-14T20:35:11.0707779Z","TriggersHash":"35243DA6","SlotName":"Production","FunctionName":"veninv","Action":"RefreshTrigger","TriggerUpdated":"[{"connection":"AzureWebJobsStorage","functionName":"veninv","path":"veninv-prod\/{name}","dataType":"binary","type":"blobTrigger","direction":"in","name":"blob","useMonitor":null}]"}
2021-10-14T20:35:11.0707779Z Created CloudStorageAccount with ConnectionString. {"Category":"ScaleControllerLogs","AppName":"veninv-Prod","Timestamp":"2021-10-14T20:35:11.0707779Z","TriggersHash":"35243DA6","SlotName":"Production","FunctionName":"veninv","Action":"TriggerInformation"}
2021-10-14T20:58:41.7386529Z Instance count changed {"Category":"ScaleControllerLogs","AppName":"veninv-Prod","Timestamp":"2021-10-14T20:58:41.7386529Z","SlotName":"Production","Action":"ScaleResult","Reason":"An instance was removed because all functions are either idle or seeing a steady decrease in load.","CurrentInstanceCount":"0","PreviousInstanceCount":"1"}
2021-10-14T20:58:41.7386529Z App is no longer assigned to any instance and may idle out at any time. {"Category":"ScaleControllerLogs","AppName":"veninv-Prod","Timestamp":"2021-10-14T20:58:41.7386529Z","SlotName":"Production","Action":"TriggerInformation","FunctionName":"N/A","TriggersHash":"35243DA6"}
