Reading Azure Service Bus Queue Names from the Config File

February 18, 2018

In this post, I wrote about how you might read a message from the service bus queue. However, with Azure Functions (and WebJobs), comes the ability to have Microsoft do some of this plumbing code for you.

I have a queue here (taken from the service bus explorer):

I can read this in an Azure function; let’s create a new Azure Functions App:

This time, we’ll create a Service Bus Queue Triggered function:

Out of the box, that will give you this:



public static class Function1
{
    [FunctionName("Function1")]
    public static void Run([ServiceBusTrigger("testqueue", AccessRights.Listen, Connection = "")]string myQueueItem, TraceWriter log)
    {
        log.Info($"C# ServiceBus queue trigger function processed message: {myQueueItem}");
    }
}

There’s a few things that we’ll probably want to change here. The first is “Connection”. We can remove that parameter altogether, and then add a row to the local.settings.json file (which can be overridden later inside Azure). Out of the box, you get AzureWebJobsStorage and AzureWebJobsDashboard, which both accept a connection string to a Azure Storage Account. You can also add AzureWebJobsServiceBus, which accepts a connection string to the service bus:



"Values": {
    "AzureWebJobsStorage": "DefaultEndpointsProtocol=https;AccountName=teststorage1…",
    "AzureWebJobsDashboard": "DefaultEndpointsProtocol=https;AccountName=teststorage1…",
    "AzureWebJobsServiceBus": "Endpoint=sb://pcm-servicebustest.servicebus.windows.net/;SharedAccessKeyName=RootManageSharedAccessKey;SharedAccessKey=…"
  }

If you run the job, it will now pick up any outstanding entries in that queue. But, what if you don’t know the queue name; for example, what if you find out the queue name is different. To illustrate the point; here, I’m looking for “testqueue1”, but the queue name (as you saw earlier) is “testqueue”:

[code lang=“c-sharp”] public static class Function1 { [FunctionName(“Function1”)]     public static void Run([ServiceBusTrigger(“testqueue1”, AccessRights.Listen)]string myQueueItem, TraceWriter log)     {      log.Info($“C# ServiceBus queue trigger function processed message: {myQueueItem}”);     } }




Obviously, if you're looking for a queue that doesn't exist, bad things happen:

[![](http://pmichaels.net/wp-content/uploads/2018/02/service-bus-config-4-300x170.png)](http://pmichaels.net/wp-content/uploads/2018/02/service-bus-config-4.png)

To fix this, I have to change the code… which is broadly speaking a bad thing.  What we can do, is configure the queue name in the config file; like this:



``` js



"Values": {
    "AzureWebJobsStorage": " . . . ",
    . . .,
    "queue-name":  "testqueue"
  }

And we can have the function look in the config file by changing the queue name:

[code lang=“c-sharp”] [FunctionName(“Function1”)] public static void Run([ServiceBusTrigger(“%queue-name%”, AccessRights.Listen)]string myQueueItem, TraceWriter log) { log.Info($“C# ServiceBus queue trigger function processed message: {myQueueItem}”); }




The pattern of supplying a variable name in the format "%variable-name%" seems to work across other triggers and bindings for Azure Functions.

# Deployment

That's now looking much better, but what happens when the function gets deployed?  Let's see:

[![](http://pmichaels.net/wp-content/uploads/2018/02/service-bus-config-5-300x164.png)](http://pmichaels.net/wp-content/uploads/2018/02/service-bus-config-5.png)

[![](http://pmichaels.net/wp-content/uploads/2018/02/service-bus-config-6-300x224.png)](http://pmichaels.net/wp-content/uploads/2018/02/service-bus-config-6.png)

We can now see that the function is deployed:

[![](http://pmichaels.net/wp-content/uploads/2018/02/service-bus-config-7-300x136.png)](http://pmichaels.net/wp-content/uploads/2018/02/service-bus-config-7.png)

At the minute, it won't do anything, because it's looking for a queue name in a setting that only exists locally.  Let's fix that:

[![](http://pmichaels.net/wp-content/uploads/2018/02/service-bus-config-8-300x254.png)](http://pmichaels.net/wp-content/uploads/2018/02/service-bus-config-8.png)

Remember to save the changes.

Looking at the logs confirms that this now runs correctly.

[![](http://pmichaels.net/wp-content/uploads/2018/02/service-bus-config-9-300x108.png)](http://pmichaels.net/wp-content/uploads/2018/02/service-bus-config-9.png)


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