Manage your function app

Article
08/21/2024

In Azure Functions, a function app provides the execution context for your individual functions. Function app behaviors apply to all functions hosted by a given function app. All functions in a function app must be of the same language.

Individual functions in a function app are deployed together and are scaled together. All functions in the same function app share resources, per instance, as the function app scales.

Connection strings, environment variables, and other application settings are defined separately for each function app. Any data that must be shared between function apps should be stored externally in a persisted store.

Get started in the Azure portal

Note

Don't mix local development with portal development in the same function app. When you create and publish functions from a local project, you won't be able to maintain or modify project code in the portal.

To view the app settings in your function app, follow these steps:

Sign in to the Azure portal using your Azure account. Search for your function app and select it.
In the left pane of your function app, expand Settings, select Environment variables, and then select the App settings tab.

Work with application settings

In addition to the predefined app settings used by Azure Functions, you can create any number of app settings, as required by your function code. For more information, see App settings reference for Azure Functions.

These settings are stored encrypted. For more information, see App settings security.

You can manage app settings from the Azure portal, and by using the Azure CLI and Azure PowerShell. You can also manage app settings from Visual Studio Code and from Visual Studio.

To view your app settings, see Get started in the Azure portal.

The App settings tab maintains settings that are used by your function app:

To see the values of the app settings, select Show values.
To add a setting, select + Add, and then enter the Name and Value of the new key-value pair.

The az functionapp config appsettings list command returns the existing application settings, for example:

az functionapp config appsettings list --name <FUNCTION_APP_NAME> \
--resource-group <RESOURCE_GROUP_NAME>

The az functionapp config appsettings set command adds or updates an application setting. The following example creates a setting with a key named CUSTOM_FUNCTION_APP_SETTING and a value of 12345:

az functionapp config appsettings set --name <FUNCTION_APP_NAME> \
--resource-group <RESOURCE_GROUP_NAME> \
--settings CUSTOM_FUNCTION_APP_SETTING=12345

The Get-AzFunctionAppSetting cmdlet returns the existing application settings, for example:

Get-AzFunctionAppSetting -Name <FUNCTION_APP_NAME> -ResourceGroupName <RESOURCE_GROUP_NAME>

The Update-AzFunctionAppSetting command adds or updates an application setting. The following example creates a setting with a key named CUSTOM_FUNCTION_APP_SETTING and a value of 12345:

Update-AzFunctionAppSetting -Name <FUNCTION_APP_NAME> -ResourceGroupName <RESOURCE_GROUP_NAME> -AppSetting @{"CUSTOM_FUNCTION_APP_SETTING" = "12345"}

Use application settings

The function app settings values can also be read in your code as environment variables. For more information, see the Environment variables section of these language-specific reference topics:

When you develop a function app locally, you must maintain local copies of these values in the local.settings.json project file. For more information, see Local settings file.

FTPS deployment settings

Azure Functions supports deploying project code to your function app by using FTPS. Because this deployment method requires you to sync triggers, it isn't recommended. To securely transfer project files, always use FTPS and not FTP.

To get the credentials required for FTPS deployment, use one of these methods:

You can get the FTPS publishing credentials in the Azure portal by downloading the publishing profile for your function app.

Important

The publishing profile contains important security credentials. Always secure the downloaded file on your local computer.

To download the publishing profile of your function app:

Select the function app's Overview page, and then select Get publish profile.
Save and copy the contents of the file.

In the file, locate the publishProfile element with the attribute publishMethod="FTP". In this element, the publishUrl, userName, and userPWD attributes contain the target URL and credentials for FTPS publishing.

Run this Azure CLI command that returns the FTPS credentials from the publishing profile.

az functionapp deployment list-publishing-profiles --name <APP_NAME> --resource-group <GROUP_NAME> --query "[?publishMethod=='FTP'].{URL:publishUrl, username:userName, password:userPWD}" -o table

In this example, replace <APP_NAME> with your function app name and <GROUP_NAME> with the resource group. The returned URL, username, and password columns contain the target URL and credentials for FTPS publishing.

Run this Azure PowerShell command that returns the FTPS credentials from the publishing profile.

$profile = [xml](Get-AzWebAppPublishingProfile -ResourceGroupName "<GROUP_NAME>" -Name "<APP_NAME>" -Format "Ftp") 
$profile.publishData.publishProfile | Where-Object -Property publishMethod -eq Ftp | Select-Object -Property @{Name="URL"; Expression = {$_.publishUrl}}, 
@{Name="username"; Expression = {$_.userName}}, @{Name="password"; Expression = {$_.userPWD}} | Format-Table

Hosting plan type

When you create a function app, you also create a hosting plan in which the app runs. A plan can have one or more function apps. The functionality, scaling, and pricing of your functions depend on the type of plan. For more information, see Azure Functions hosting options.

You can determine the type of plan being used by your function app from the Azure portal, or by using the Azure CLI or Azure PowerShell APIs.

The following values indicate the plan type:

Plan type	Azure portal	Azure CLI/PowerShell
Consumption	Consumption	`Dynamic`
Premium	ElasticPremium	`ElasticPremium`
Dedicated (App Service)	Various	Various

To determine the type of plan used by your function app, see the App Service Plan in the Overview page of the function app in the Azure portal.
To see the pricing tier, select the name of the App Service Plan, and then select Settings > Properties from the left pane.

Run the following Azure CLI command to get your hosting plan type:

functionApp=<FUNCTION_APP_NAME>
resourceGroup=FunctionMonitoringExamples
appServicePlanId=$(az functionapp show --name $functionApp --resource-group $resourceGroup --query appServicePlanId --output tsv)
az appservice plan list --query "[?id=='$appServicePlanId'].sku.tier" --output tsv

In the previous example, replace <RESOURCE_GROUP> and <FUNCTION_APP_NAME> with the resource group and function app names, respectively.

Run the following Azure PowerShell command to get your hosting plan type:

$FunctionApp = '<FUNCTION_APP_NAME>'
$ResourceGroup = '<RESOURCE_GROUP>'

$PlanID = (Get-AzFunctionApp -ResourceGroupName $ResourceGroup -Name $FunctionApp).AppServicePlan
(Get-AzFunctionAppPlan -Name $PlanID -ResourceGroupName $ResourceGroup).SkuTier

In the previous example, replace <RESOURCE_GROUP> and <FUNCTION_APP_NAME> with the resource group and function app names, respectively.

Plan migration

You can migrate a function app between a Consumption plan and a Premium plan on Windows. When migrating between plans, keep in mind the following considerations:

Direct migration to a Dedicated (App Service) plan isn't supported.
Migration isn't supported on Linux.
The source plan and the target plan must be in the same resource group and geographical region. For more information, see Move an app to another App Service plan.
The specific CLI commands depend on the direction of the migration.
Downtime in your function executions occurs as the function app is migrated between plans.
State and other app-specific content is maintained, because the same Azure Files share is used by the app both before and after migration.

You can migrate your plan using these tools:

You can use the Azure portal to switch to a different plan.

Choose the direction of the migration for your app on Windows.

In the Azure portal, navigate to your Consumption plan app and choose Change App Service plan under App Service plan.
Select Premium under Plan type, create a new Premium plan, and select OK.

For more information, see Move an app to another App Service plan.

Use the following procedure to migrate from a Consumption plan to a Premium plan on Windows:

Run the az functionapp create command as follows to create a new App Service plan (Elastic Premium) in the same region and resource group as your existing function app:
```
az functionapp plan create --name <NEW_PREMIUM_PLAN_NAME> --resource-group <MY_RESOURCE_GROUP> --location <REGION> --sku EP1
```
Run the az functionapp update command as follows to migrate the existing function app to the new Premium plan:
```
az functionapp update --name <MY_APP_NAME> --resource-group <MY_RESOURCE_GROUP> --plan <NEW_PREMIUM_PLAN>
```
When you no longer need the Consumption plan originally used by the app, delete your original plan after confirming you've successfully migrated to the new one. Run the az functionapp plan list command as follows to get a list of all Consumption plans in your resource group:
```
az functionapp plan list --resource-group <MY_RESOURCE_GROUP> --query "[?sku.family=='Y'].{PlanName:name,Sites:numberOfSites}" -o table
```
You can safely delete the plan with zero sites, which is the one you migrated from.
Run the az functionapp plan delete command as follows to delete the Consumption plan you migrated from.
```
az functionapp plan delete --name <CONSUMPTION_PLAN_NAME> --resource-group <MY_RESOURCE_GROUP>
```

Use the following procedure to migrate from a Premium plan to a Consumption plan on Windows:

Run the az functionapp create command as follows to create a new function app (Consumption) in the same region and resource group as your existing function app. This command also creates a new Consumption plan in which the function app runs:
```
az functionapp create --resource-group <MY_RESOURCE_GROUP> --name <NEW_CONSUMPTION_APP_NAME> --consumption-plan-location <REGION> --runtime <LANGUAGE_RUNTIME> --functions-version 4 --storage-account <STORAGE_NAME>
```
Run the az functionapp show command as follows to get the name of the Consumption plan created with the new function app:
```
az functionapp show --resource-group <MY_RESOURCE_GROUP> --name <NEW_CONSUMPTION_APP_NAME> --query "{appServicePlanId}" -o tsv
```
The Consumption plan name is the final segment of the fully qualified resource ID that is returned.

Run the az functionapp update command as follows to migrate the existing function app to the new Consumption plan:

az functionapp update --name <MY_APP_NAME> --resource-group <MY_RESOURCE_GROUP> --plan <NEW_CONSUMPTION_PLAN> --force

Run the az functionapp delete command as follows to delete the function app you created in step 1, since you only need the plan that was created to run the existing function app:
```
az functionapp delete --name <NEW_CONSUMPTION_APP_NAME> --resource-group <MY_RESOURCE_GROUP>
```
When you no longer need the Premium plan originally used by the app, delete your original plan after confirming you've successfully migrated to the new one. Until the Premium plan is deleted, you continue to be charged for it. Run the az functionapp plan list command as follows to get a list of all Premium plans in your resource group:
```
az functionapp plan list --resource-group <MY_RESOURCE_GROUP> --query "[?sku.family=='EP'].{PlanName:name,Sites:numberOfSites}" -o table
```
Run the az functionapp plan delete command as follows to delete the Premium plan you migrated from:
```
az functionapp plan delete --name <PREMIUM_PLAN> --resource-group <MY_RESOURCE_GROUP>
```

Use the following procedure to migrate from a Consumption plan to a Premium plan on Windows:

Run the New-AzFunctionAppPlan command as follows to create a new App Service plan (Elastic Premium) in the same region and resource group as your existing function app:
```
New-AzFunctionAppPlan -Name <NEW_PREMIUM_PLAN_NAME> -ResourceGroupName <MY_RESOURCE_GROUP> -Location <REGION> -Sku EP1 -WorkerType Windows
```

Run the Update-AzFunctionApp command as follows to migrate the existing function app to the new Premium plan:

Update-AzFunctionApp -Name <MY_APP_NAME> -ResourceGroupName <MY_RESOURCE_GROUP> -PlanName <NEW_PREMIUM_PLAN> -Force

When you no longer need the Consumption plan originally used by the app, you can run the Remove-AzFunctionAppPlan command as follows to delete the Consumption plan you migrated from:
```
Remove-AzFunctionAppPlan -Name <CONSUMPTION_PLAN_NAME> -ResourceGroupName <MY_RESOURCE_GROUP> -Force
```

Use the following procedure to migrate from a Premium plan to a Consumption plan on Windows:

Run the New-AzFunctionApp command as follows to create a new function app (Consumption) in the same region and resource group as your existing function app. This command also creates a new Consumption plan in which the function app runs:

New-AzFunctionApp -Name <NEW_CONSUMPTION_APP_NAME> -StorageAccountName <STORAGE_NAME> -Location <REGION> -ResourceGroupName <MY_RESOURCE_GROUP> -Runtime <LANGUAGE_RUNTIME> -RuntimeVersion <LANGUAGE_VERSION> -FunctionsVersion 4 -OSType Windows

Run the Get-AzFunctionApp command as follows to get the name of the Consumption plan created with the new function app:

Get-AzFunctionApp -ResourceGroupName <MY_RESOURCE_GROUP> -Name <NEW_CONSUMPTION_APP_NAME> | Select-Object -Property AppServicePlan | Format-List

Run the Update-AzFunctionApp command as follows to migrate the existing function app to the new Consumption plan:

Update-AzFunctionApp -Name <MY_APP_NAME> -ResourceGroupName <MY_RESOURCE_GROUP> -PlanName <NEW_CONSUMPTION_PLAN> -Force

When you no longer need the Consumption plan originally used by the app, you can run the Remove-AzFunctionAppPlan command as follows to delete the Consumption plan you migrated from:
```
Remove-AzFunctionAppPlan -Name <CONSUMPTION_PLAN_NAME> -ResourceGroupName <MY_RESOURCE_GROUP> -Force
```

Development limitations in the Azure portal

Consider these limitations when you develop your functions in the Azure portal:

In-portal editing is supported only for functions that were created or last modified in the Azure portal.
In-portal editing is supported only for JavaScript, PowerShell, Python, and C# Script functions.
In-portal editing isn't supported in the preview release of the Flex Consumption plan.
When you deploy code to a function app from outside the Azure portal, you can no longer edit any of the code for that function app in the portal. In this case, just continue using local development.
For Python, development with custom modules isn't currently supported in the portal. To add custom modules to your function app, you must develop your app locally.
For compiled C# functions and Java functions, you can create the function app and related resources in the portal. However, you must create the functions code project locally and then publish it to Azure.

When possible, develop your functions locally and publish your code project to a function app in Azure. For more information, see Code and test Azure Functions locally.

Manually install extensions

C# class library functions can include the NuGet packages for binding extensions directly in the class library project. For other non-.NET languages and C# script, you should use extension bundles. If you must manually install extensions, you can do so by using Azure Functions Core Tools locally. If you can't use extension bundles and are only able to work in the portal, you need to use Advanced Tools (Kudu) to manually create the extensions.csproj file directly in the site. Make sure to first remove the extensionBundle element from the host.json file.

This same process works for any other file you need to add to your app.

Important

When possible, don't edit files directly in your function app in Azure. We recommend downloading your app files locally, using Core Tools to install extensions and other packages, validating your changes, and then republishing your app using Core Tools or one of the other supported deployment methods.

The Functions editor built into the Azure portal lets you update your function code and configuration files directly in the portal:

Select your function app, then under Functions, select Functions.
Choose your function and select Code + test under Developer.
Choose your file to edit and select Save when you finish.

Files in the root of the app, such as function.proj or extensions.csproj need to be created and edited by using the Advanced Tools (Kudu):

Select your function app, expand Development tools, and then select Advanced tools > Go.
If prompted, sign in to the Source Control Manager (SCM) site with your Azure credentials.
From the Debug console menu, choose CMD.
Navigate to .\site\wwwroot, select the plus (+) button at the top, and select New file.
Give the file a name, such as extensions.csproj, and then press Enter.
Select the edit button next to the new file, add or update code in the file, and then select Save.
For a project file like extensions.csproj, run the following command to rebuild the extensions project:
```
dotnet build extensions.csproj
```

Platform features

Function apps run in the Azure App Service platform, which maintains them. As such, your function apps have access to most of the features of Azure's core web hosting platform. When you use the Azure portal, the left pane is where you access the many features of the App Service platform that you can use in your function apps.

The following matrix indicates Azure portal feature support by hosting plan and operating system:

Feature	Consumption plan	Flex Consumption plan	Premium plan	Dedicated plan
Advanced tools (Kudu)	Windows: ✔ Linux: X	X	✔	✔
App Service editor	Windows: ✔ Linux: X	X	Windows: ✔ Linux: X	Windows: ✔ Linux: X
Backups	X	X	X	✔
Console	Windows: command-line Linux: X	X	Windows: command-line Linux: SSH	Windows: command-line Linux: SSH

The rest of this article focuses on the following features in the portal that are useful for your function apps:

App Service editor
Console
Advanced tools (Kudu)
Deployment options
CORS
Authentication

For more information about how to work with App Service settings, see Configure Azure App Service Settings.

App Service editor

The App Service editor is an advanced in-portal editor that you can use to modify JSON configuration files and code files alike. Choosing this option launches a separate browser tab with a basic editor. This editor enables you to integrate with the Git repository, run and debug code, and modify function app settings. This editor provides an enhanced development environment for your functions compared with the built-in function editor.

Screenshot that shows the App Service editor.

We recommend that you consider developing your functions on your local computer. When you develop locally and publish to Azure, your project files are read-only in the Azure portal. For more information, see Code and test Azure Functions locally.

Console

The in-portal console is an ideal developer tool when you prefer to interact with your function app from the command line. Common commands include directory and file creation and navigation, as well as executing batch files and scripts.

Screenshot that shows the function app console.

When developing locally, we recommend using the Azure Functions Core Tools and the Azure CLI.

Advanced tools (Kudu)

The advanced tools for App Service (also known as Kudu) provide access to advanced administrative features of your function app. From Kudu, you manage system information, app settings, environment variables, site extensions, HTTP headers, and server variables. You can also launch Kudu by browsing to the SCM endpoint for your function app, for example: https://<myfunctionapp>.scm.chinacloudsites.cn/.

Screenshot that shows the advanced tools for App Service (Kudo).

Deployment Center

When you use a source control solution to develop and maintain your functions code, Deployment Center lets you build and deploy from source control. Your project is built and deployed to Azure when you make updates. For more information, see Deployment technologies in Azure Functions.

Cross-origin resource sharing

To prevent malicious code execution on the client, modern browsers block requests from web applications to resources running in a separate domain. Cross-origin resource sharing (CORS) lets an Access-Control-Allow-Origin header declare which origins are allowed to call endpoints on your function app.

When you configure the Allowed origins list for your function app, the Access-Control-Allow-Origin header is automatically added to all responses from HTTP endpoints in your function app.

Screenshot that shows how to configure CORS list of your function app.

If there's another domain entry, the wildcard (*) is ignored.

Use the az functionapp cors add command to add a domain to the allowed origins list. The following example adds the contoso.com domain:

az functionapp cors add --name <FUNCTION_APP_NAME> \
--resource-group <RESOURCE_GROUP_NAME> \
--allowed-origins https://contoso.com

Use the az functionapp cors show command to list the current allowed origins.

Authentication

When functions use an HTTP trigger, you can require calls to first be authenticated. App Service supports Microsoft Entra authentication and sign-in with social providers. For details on configuring specific authentication providers, see Azure App Service authentication overview.

Screenshot that shows how to configure authentication for a function app.

Configure an App Service app