Disable certain Azure functions using any configuration

Question

While using Azure functions, I have a situation where I want a few functions in "disabled" mode for a function app, while others to be enabled. The thing is, I don't want to do it manually using the functions screen where individual functions could be enabled/disabled easily. There is this article that says Functions 2.x supports this (Functions 1.x is not a choice for me).

https://docs.microsoft.com/en-us/azure/azure-functions/disable-function

It is just that the article is a little vague about what needs to be done. It says and I quote >

In Functions 2.x you disable a function by using an app setting. For example, to disable a function named QueueTrigger, you create an app setting named AzureWebJobs.QueueTrigger.Disabled, and set it to true. To enable the function, set the app setting to false.

I tried this, but it doesn't work as documented. I have a function app called foo and a function called bar. I have tried both:

disabled: true in function.json

as well as:

foo: { 
  bar: {
    disabled: true
  }
}

After making these changes and redeploying there is no effect on the UI. What am I missing?

Turbo Turbo · Accepted Answer · 2019-06-02T01:29:16

The recommended approach is by using app settings, which you can do by going to the portal. [Note: They don't mean function.json when they say app settings.]

Option 1: Using App Settings In azure portal, navigate to your function app foo -> Confuguration, and you should see Application Settings tab with a few variables already defined. You need to create a new variable by clicking New application setting button. Set name as AzureWebJobs.bar.Disabled and value as true. Note that the function app name foo doesn't figure in the variable name.

Option 2: Using host.json Because you are looking for disabling a function from code, you can try doing this in host.json. Note that this is intended for local development, and not recommended for prod, but it works. https://docs.microsoft.com/en-us/azure/azure-functions/functions-host-json#functions

{
    "functions": [ "function1", "function2" ] // Don't list function "bar" here, and it would get disabled.
}

Note that the portal will not show this correctly, and list "bar" as enabled, but you will get 404 when hitting that function.

Option 3: Using Disable attribute If you are using C# You can also use the [Disable] attribute. This is a Functions 1.x construct, but it works in 2.x as well. Similar to above, the portal UI will not show this correctly.

    [Disable]
    [FunctionName("Function1")]
    public static async Task<IActionResult> Run(
    [HttpTrigger(AuthorizationLevel.Anonymous, "get", "post", Route = null)] HttpRequest req,
    ILogger log)
{
}

Option 4: By removing FunctionName attribute Only if you are using C#. This might sound counter-intuitive, but if you remove the FunctionName attribute from your function, it won't be treated as such.

    // [FunctionName("Function1")]  // Comment this or delete this line to disable this function
    public static async Task<IActionResult> Run(
    [HttpTrigger(AuthorizationLevel.Anonymous, "get", "post", Route = null)] HttpRequest req,
    ILogger log)
{
}

This should work in both runtimes. The function wouldn't show in the azure portal.

Disable certain Azure functions using any configuration

1 Answers