disable-function.md

title	description	ms.topic	ms.date
How to disable functions in Azure Functions	Learn how to disable and enable functions in Azure Functions.	conceptual	04/08/2020

How to disable functions in Azure Functions

This article explains how to disable a function in Azure Functions. To disable a function means to make the runtime ignore the automatic trigger that's defined for the function. This lets you prevent a specific function from running without stopping the entire function app.

The recommended way to disable a function is by using an app setting in the format AzureWebJobs.<FUNCTION_NAME>.Disabled. You can create and modify this application setting in a number of ways, including by using the Azure CLI and from your function's Manage tab in the Azure portal.

Note

When you disable an HTTP triggered function by using the methods described in this article, the endpoint may still by accessible when running on your local computer.

Use the Azure CLI

In the Azure CLI, you use the az functionapp config appsettings set command to create and modify the app setting. The following command disables a function named QueueTrigger by creating an app setting named AzureWebJobs.QueueTrigger.Disabled set it to true.

az functionapp config appsettings set --name <myFunctionApp> \
--resource-group <myResourceGroup> \
--settings AzureWebJobs.QueueTrigger.Disabled=true

To re-enable the function, rerun the same command with a value of false.

az functionapp config appsettings set --name <myFunctionApp> \
--resource-group <myResourceGroup> \
--settings AzureWebJobs.QueueTrigger.Disabled=false

Use the Portal

You can also use the Enable and Disable buttons on the function's Overview page. These buttons work by creating and deleting the AzureWebJobs.<FUNCTION_NAME>.Disabled app setting.

Note

The portal-integrated testing functionality ignores the Disabled setting. This means that a disabled function still runs when started from the Test window in the portal.

Other methods

While the application setting method is recommended for all languages and all runtime versions, there are several other ways to disable functions. These methods, which vary by language and runtime version, are maintained for backward compatibility.

C# class libraries

In a class library function, you can also use the Disable attribute to prevent the function from being triggered. You can use the attribute without a constructor parameter, as shown in the following example:

public static class QueueFunctions
{
    [Disable]
    [FunctionName("QueueTrigger")]
    public static void QueueTrigger(
        [QueueTrigger("myqueue-items")] string myQueueItem, 
        TraceWriter log)
    {
        log.Info($"C# function processed: {myQueueItem}");
    }
}

The attribute without a constructor parameter requires that you recompile and redeploy the project to change the function's disabled state. A more flexible way to use the attribute is to include a constructor parameter that refers to a Boolean app setting, as shown in the following example:

public static class QueueFunctions
{
    [Disable("MY_TIMER_DISABLED")]
    [FunctionName("QueueTrigger")]
    public static void QueueTrigger(
        [QueueTrigger("myqueue-items")] string myQueueItem, 
        TraceWriter log)
    {
        log.Info($"C# function processed: {myQueueItem}");
    }
}

This method lets you enable and disable the function by changing the app setting, without recompiling or redeploying. Changing an app setting causes the function app to restart, so the disabled state change is recognized immediately.

Important

The Disabled attribute is the only way to disable a class library function. The generated function.json file for a class library function is not meant to be edited directly. If you edit that file, whatever you do to the disabled property will have no effect.

The same goes for the Function state switch on the Manage tab, since it works by changing the function.json file.

Also, note that the portal may indicate the function is disabled when it isn't.

Functions 1.x - scripting languages

In version 1.x, you can also use the disabled property of the function.json file to tell the runtime not to trigger a function. This method only works for scripting languages such as C# script and JavaScript. The disabled property can be set to true or to the name of an app setting:

{
    "bindings": [
        {
            "type": "queueTrigger",
            "direction": "in",
            "name": "myQueueItem",
            "queueName": "myqueue-items",
            "connection":"MyStorageConnectionAppSetting"
        }
    ],
    "disabled": true
}

or

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

In the second example, the function is disabled when there is an app setting that is named IS_DISABLED and is set to true or 1.

Important

The portal now uses application settings to disable v1.x functions. When an application setting conflicts with the function.json file, an error can occur. You should remove the disabled property from the function.json file to prevent errors.

Next steps

This article is about disabling automatic triggers. For more information about triggers, see Triggers and bindings.