Working with Azure Functions in Visual Studio Code like a boss

So after a while I decided to finally check Azure Functions extensions out in Visual Studio Code. I often want to check something really quickly and being forced to open Visual Studio each time makes me furious. I must say that initially I was a bit skeptical regarding Code functionality, but it turns out to be superb. Let's check what it offers for now.


Installing the extensions is super easy. Just go to the Extensions menu and search for Azure Functions:

Once extensions is installed you can easily disable or uninstall it

For now - that's really all!

Creating a function

With Azure Functions plugin installed you should be able to see available subscriptions in the Explorer area. If not left-click on the status bar where your username is displayed and select the ones you're interested in:

Workspace with only one subscription selected


Installing the extension gives you some more features. Now you're able to work with a project, create a function and publish it. Let's start with a function triggered by a HTTP request. Click on "Create New Project Button":

Now you're able to select a current location or create a new one where your project will be placed. Once you're satisfied you can select a language and... that's all, your workspace is ready to start working on a function.

Empty Functions project ready to rock!

Now let's create a function. You can create in in a similar way as a project. After providing all necessary data(like a name, a type of trigger, security level), a template will be created so you can start modyfing it as you wish.

A template, very similar to the one created in Visual Studio

Running a function

You can easily start testing your function by pressing F5. It'll start runtime and you'll be given an endpoint, which you can call anytime:

Publishing a function

Publishing a function from Visual Studio Code is as easy as other tasks. Once more go to the Azure Functions workspace and select "Deploy to Function App". You'll be asked about many different parameters like a subscription, resource group or storage account. Once everything's configured wait a second(or maybe two) until a function is published. You can start using it!

Function published along with a storage account and consumption plan


In the current shape VS Code will not replace full Visual Studio(at least for me personally), but I found Azure Functions extension extremely helpful in the smaller projects, which are developed fully in Code. If I don't have to switch between IDEs, I'm more than happy. 

Don't "admin" me!

This was somehow unexpected. I was flawlessly developing my API using Azure Functions and then BANG! - suddenly my functions are in error state. Just like that - no stack trace, no detailed explanation. I took me some time to realize, that they all have one thing in common - they share the admin part. Apparently Functions have some problems when you're using HttpTrigger with a custom route containg admin word. What is the reason?

Check the codebase

Let's take a quick look at the codebase of Functions. Finding a place, which causes the error is pretty simple:

internal static void ValidateHttpFunction(string functionName, HttpTriggerAttribute httpTrigger, bool isProxy = false)
	if (string.IsNullOrWhiteSpace(httpTrigger.Route) && !isProxy)
		// if no explicit route is provided, default to the function name
		httpTrigger.Route = functionName;

	// disallow custom routes in our own reserved route space
	string httpRoute = httpTrigger.Route.Trim('/').ToLowerInvariant();
	if (httpRoute.StartsWith("admin"))
		throw new InvalidOperationException("The specified route conflicts with one or more built in routes.");

As you can see, all routes which start with admin are disallowed. While this is perfectly fine, I couldn't find any mention in the documentation, which would clarify this. 

When in doubt always try to check the source. Some answers will be quite difficult to obtain, but you'll end up with a much better overall understanding of the library. The rest will be rather straightforward, nothing you can't handle, isn't it?