Why does my Azure Function sometimes stop being triggered

Azure is so awesome because the features it provides are so very dynamic and flexible.  The platform provides a starting point for the fruition of ideas, ideas only limited by ones imagination.  With its dynamic nature and the flexibility it delivers to consumers, sometimes you just need a note to get your ideas optimally flowing on the platform.

Three points (for now) you need to keep in mind when creating and managing your Azure Function App:

• All your Azure Functions run within a Azure Function App
• The way in which you deploy your Azure Function is important
• The trigger type you choose comes with scenarios specific only (in some cases) to that trigger type

Like with an Azure App Service, where each runs within its own W3WP process so does the Azure Function App.  If you then access KUDU/SCM and navigate to the D:homesitewwwroot directory via the CMD console, you will see the Azure Functions which run inside that same W3WP process, Figure 1.

Figure 1, why does my Azure Function not get triggered, Azure Function stops

This correlates one-to-one with what is seen in the Azure portal, Figure 2.

Figure 2, why does my Azure Function not get triggered, Azure Function stops

There are numerous methods for deploying, managing and creating an Azure Function, I wrote a few methods here:

• How to create an Azure Function in Visual Studio
• Deploy an Azure Function created from Visual Studio
• How to configure GitHub or VSTS for use with an Azure Function
• Debugging Azure Functions in Visual Studio

The issue most know for causing Azure Functions to not trigger is that some deployment or IDEs do not trigger a synchronization on a Consumption plan with the central listener.  See here “New integrated portal for Azure Functions” and here “Document deployment options related to trigger syncing”.  Those articles explain a bit more about this.

You can trigger a synchronization using the following PowerShell command.

Login-AzureRmAccount
Set-AzureRmContext -SubscriptionId "<Subscription Id>"
$WebAppApiVersion = "2018-02-01"
$ResourceType = "Microsoft.Web/sites"
$ResourceGroupName = "<Resource Group Name>"
$SiteName = "<Azure Function App Name>"
Write-Output "PowerShell function executed at:$(get-date)";
Invoke-AzureRmResourceAction 
     -ResourceGroupName $ResourceGroupName 
     -ResourceType $ResourceType 
     -ResourceName $SiteName 
     -Action syncfunctiontriggers 
     -ApiVersion $WebAppApiVersion -Force

There are numerous trigger types and bindings.  Here are a few:

• Azure Blob storage bindings for Azure Functions
• Azure Event Hubs bindings for Azure Functions
• Azure Service Bus bindings for Azure Functions
• Azure Functions HTTP and webhook bindings
• …

Study each of the binding types and you learn the unique attributes of each.