Azure Function App = run single Azure Function locally to debug

Question

In visual studio I have created an Azure Function App with several Function.

When I launch the Function App debugger from the tool bar all Functions are triggered.

Is there a way to trigger a single function from the App within Visual Studio 2017?

Are you trying to debug a Function running locally or in Azure? What language are you using for your function, C#? — Thomas, Oct 16 '18 at 14:31

score 36 · Accepted Answer · answered Oct 16 '18 at 22:06

36

There is no easy way to achieve this, but it is possible.

by modifying the function.json file:

"bindings": [
...
],
"disabled": true

or by using the [Disable] attribute:

[Disable]
[FunctionName("Function")]
[NoAutomaticTrigger]
public static void Function(string input, TraceWriter log)
{ }

Run function using command: func run <functionName>

In your host.json file specify functions that should be run:

{ 
   "functions":[ "FunctionToRun" ]
}

answered Oct 16 '18 at 22:06

Pawel Maga

1

Thanks for the solution. I am using VS2019 and I tried no:3 - it is working fine – Joe 89 Apr 08 '19 at 02:21
func run , the func is an unknown command error – Indrajeet Singh May 16 '22 at 13:12
The host.json method works perfectly – Rob Sedgwick Jun 20 '23 at 16:26

Yash Mochi · Answer 2 · 2022-05-25T07:46:53.063

9

As @Pawel Maga mentioned there are three ways.

I have a little better approach for 3rd option (Specify functions in the host.json file).

Instead of messing with host.json (we might forget to undo while publishing.. i have done it many times :p).

We can override functions array by setting value in local.settings.json.

For example: Set like below code in local.settings.json

{
  "Values": {
    "AzureFunctionsJobHost__functions__0":  "FunctionToRun",
    "AzureFunctionsJobHost__functions__1":  "SecondFunctionToRun",
  }
}

Instead of writing below code in host.json

{ 
   "functions":[ "FunctionToRun", "SecondFunctionToRun" ]
}

edited May 25 '22 at 07:46

answered Dec 05 '20 at 10:45

Yash Mochi

I would've never figured out that the right way to pass multiple values to `AzureFunctionsJobHost__functions` was to break them into separate lines with `__x` at the end, big thanks! – Sebastián Vansteenkiste Jan 05 '23 at 19:40

score 6 · Answer 3 · answered Sep 16 '21 at 18:20

As an update to the above answers: it appears that you can disable functions in the localsettings.json in this way.

{
  "Values": {
    "AzureWebJobs.MyFirstFunction.Disabled": true,
    "AzureWebJobs.MySecondFunction.Disabled": true
  }
}

This is what I'm planning to do for our team as it has the nicest syntax of the "safe" options (approaches that don't have to be undone on publish).

3 Answers3