Messages disappearing from queue after Azure Functions start

Question

So I'm doing some testing with Azure WebApp + Azure Storage Queue + Azure Functions. Normally everything works great, however if I try to emulate the failure of the Functions App (with Stop-AzureRmWebApp) add message, start the Functions App, the messages get consumed, but not processed (and never returns to the queue). I'm using python to process data, but I don't think that matters at all. It appears that the messages just disappear.

I'm using S1 plan (not dynamic) with AlwaysOn.

Nothing reasonable in logs (these 3 executions are from before I disabled the Function App):

2016-11-30T11:33:48.216 Executing: 'Functions.somename' - Reason: 'New queue message detected on 'queueName'.'
2016-11-30T11:33:48.216 Executing: 'Functions.somename' - Reason: 'New queue message detected on 'queueName'.'
2016-11-30T11:33:48.216 Executing: 'Functions.somename' - Reason: 'New queue message detected on 'queueName'.'
2016-11-30T11:33:48.216 Function started (Id=dc9fa205-6ddf-47e5-b529-90ccee2ddf0e)
2016-11-30T11:33:48.232 Function started (Id=5421bc7f-c438-4ffb-82e9-f7021604c247)
2016-11-30T11:33:48.232 Function started (Id=bb42ab71-3389-4668-a7f4-3d90d5cd96eb)
2016-11-30T11:33:54.576 Function completed (Success, Id=dc9fa205-6ddf-47e5-b529-90ccee2ddf0e)
2016-11-30T11:33:54.576 Executed: 'Functions.somename' (Succeeded)
2016-11-30T11:33:54.670 Function completed (Success, Id=5421bc7f-c438-4ffb-82e9-f7021604c247)
2016-11-30T11:33:54.670 Executed: 'Functions.somename' (Succeeded)
2016-11-30T11:33:54.685 Function completed (Success, Id=bb42ab71-3389-4668-a7f4-3d90d5cd96eb)
2016-11-30T11:33:54.685 Executed: 'Functions.somename' (Succeeded)

mathewc mathewc · Accepted Answer · 2016-11-30T16:30:23

I suspect that your messages are getting successfully processed by your function. Check the Monitor tab for the executions. The monitor tab is where you can find all historical executions for your function.

The log window in the portal is for active debug sessions only - i.e. you're live in the portal running/debugging your function. E.g. those logs disable themselves after some time when the portal is disconnected. Also, if you had the portal open on the log window and stopped the Function App, that could cause the log stream to be disconnected, causing the logs not to show in the window. To test that theory, after your stop/start you could pause/start the log stream again and it should show any recent executions that happened while it was disconnected.

Messages disappearing from queue after Azure Functions start

1 Answers