title	description	ms.topic	ms.date
App settings reference for Azure Functions	Reference documentation for the Azure Functions app settings or environment variables.	conceptual	07/27/2021

App settings reference for Azure Functions

App settings in a function app contain global configuration options that affect all functions for that function app. When you run locally, these settings are accessed as local environment variables. This article lists the app settings that are available in function apps.

[!INCLUDE Function app settings]

There are other global configuration options in the host.json file and in the local.settings.json file. Example connection string values are truncated for readability.

Note

You can use application settings to override host.json setting values without having to change the host.json file itself. This is helpful for scenarios where you need to configure or modify specific host.json settings for a specific environment. This also lets you change host.json settings without having to republish your project. To learn more, see the host.json reference article. Changes to function app settings require your function app to be restarted.

APPINSIGHTS_INSTRUMENTATIONKEY

The instrumentation key for Application Insights. Only use one of APPINSIGHTS_INSTRUMENTATIONKEY or APPLICATIONINSIGHTS_CONNECTION_STRING. When Application Insights runs in a sovereign cloud, use APPLICATIONINSIGHTS_CONNECTION_STRING. For more information, see How to configure monitoring for Azure Functions.

Key	Sample value
APPINSIGHTS_INSTRUMENTATIONKEY	`55555555-af77-484b-9032-64f83bb83bb`

APPLICATIONINSIGHTS_CONNECTION_STRING

The connection string for Application Insights. Use APPLICATIONINSIGHTS_CONNECTION_STRING instead of APPINSIGHTS_INSTRUMENTATIONKEY in the following cases:

When your function app requires the added customizations supported by using the connection string.
When your Application Insights instance runs in a sovereign cloud, which requires a custom endpoint.

For more information, see Connection strings.

Key	Sample value
APPLICATIONINSIGHTS_CONNECTION_STRING	`InstrumentationKey=...`

AZURE_FUNCTION_PROXY_DISABLE_LOCAL_CALL

By default, Functions proxies use a shortcut to send API calls from proxies directly to functions in the same function app. This shortcut is used instead of creating a new HTTP request. This setting allows you to disable that shortcut behavior.

Key	Value	Description
AZURE_FUNCTION_PROXY_DISABLE_LOCAL_CALL	`true`	Calls with a backend URL pointing to a function in the local function app won't be sent directly to the function. Instead, the requests are directed back to the HTTP frontend for the function app.
AZURE_FUNCTION_PROXY_DISABLE_LOCAL_CALL	`false`	Calls with a backend URL pointing to a function in the local function app are forwarded directly to the function. This is the default value.

AZURE_FUNCTION_PROXY_BACKEND_URL_DECODE_SLASHES

This setting controls whether the characters %2F are decoded as slashes in route parameters when they are inserted into the backend URL.

Key	Value	Description
AZURE_FUNCTION_PROXY_BACKEND_URL_DECODE_SLASHES	`true`	Route parameters with encoded slashes are decoded.
AZURE_FUNCTION_PROXY_BACKEND_URL_DECODE_SLASHES	`false`	All route parameters are passed along unchanged, which is the default behavior.

For example, consider the proxies.json file for a function app at the myfunction.com domain.

{
    "$schema": "http://json.schemastore.org/proxies",
    "proxies": {
        "root": {
            "matchCondition": {
                "route": "/{*all}"
            },
            "backendUri": "example.com/{all}"
        }
    }
}

When AZURE_FUNCTION_PROXY_BACKEND_URL_DECODE_SLASHES is set to true, the URL example.com/api%2ftest resolves to example.com/api/test. By default, the URL remains unchanged as example.com/test%2fapi. For more information, see Functions proxies.

AZURE_FUNCTIONS_ENVIRONMENT

In version 2.x and later versions of the Functions runtime, configures app behavior based on the runtime environment. This value is read during initialization, and can be set to any value. Only the values of Development, Staging, and Production are honored by the runtime. When this application setting isn't present when running in Azure, the environment is assumed to be Production. Use this setting instead of ASPNETCORE_ENVIRONMENT if you need to change the runtime environment in Azure to something other than Production. The Azure Functions Core Tools set AZURE_FUNCTIONS_ENVIRONMENT to Development when running on a local computer, and this can't be overridden in the local.settings.json file. To learn more, see Environment-based Startup class and methods.

AzureFunctionsJobHost__*

In version 2.x and later versions of the Functions runtime, application settings can override host.json settings in the current environment. These overrides are expressed as application settings named AzureFunctionsJobHost__path__to__setting. For more information, see Override host.json values.

AzureWebJobsDashboard

Optional storage account connection string for storing logs and displaying them in the Monitor tab in the portal. This setting is only valid for apps that target version 1.x of the Azure Functions runtime. The storage account must be a general-purpose one that supports blobs, queues, and tables. To learn more, see Storage account requirements.

Key	Sample value
AzureWebJobsDashboard	`DefaultEndpointsProtocol=https;AccountName=...`

Note

For better performance and experience, runtime version 2.x and later versions use APPINSIGHTS_INSTRUMENTATIONKEY and App Insights for monitoring instead of AzureWebJobsDashboard.

AzureWebJobsDisableHomepage

true means disable the default landing page that is shown for the root URL of a function app. Default is false.

Key	Sample value
AzureWebJobsDisableHomepage	`true`

When this app setting is omitted or set to false, a page similar to the following example is displayed in response to the URL <functionappname>.azurewebsites.net.

AzureWebJobsDotNetReleaseCompilation

true means use Release mode when compiling .NET code; false means use Debug mode. Default is true.

Key	Sample value
AzureWebJobsDotNetReleaseCompilation	`true`

AzureWebJobsFeatureFlags

A comma-delimited list of beta features to enable. Beta features enabled by these flags are not production ready, but can be enabled for experimental use before they go live.

Key	Sample value
AzureWebJobsFeatureFlags	`feature1,feature2`

AzureWebJobsSecretStorageType

Specifies the repository or provider to use for key storage. Currently, the supported repositories are blob storage ("Blob") and the local file system ("Files"). The default is blob in version 2 and file system in version 1.

Key	Sample value
AzureWebJobsSecretStorageType	Files

AzureWebJobsStorage

The Azure Functions runtime uses this storage account connection string for normal operation. Some uses of this storage account include key management, timer trigger management, and Event Hubs checkpoints. The storage account must be a general-purpose one that supports blobs, queues, and tables. See Storage account and Storage account requirements.

Key	Sample value
AzureWebJobsStorage	`DefaultEndpointsProtocol=https;AccountName=...`

AzureWebJobs_TypeScriptPath

Path to the compiler used for TypeScript. Allows you to override the default if you need to.

Key	Sample value
AzureWebJobs_TypeScriptPath	`%HOME%\typescript`

FUNCTION_APP_EDIT_MODE

Dictates whether editing in the Azure portal is enabled. Valid values are "readwrite" and "readonly".

Key	Sample value
FUNCTION_APP_EDIT_MODE	`readonly`

FUNCTIONS_EXTENSION_VERSION

The version of the Functions runtime that hosts your function app. A tilde (~) with major version means use the latest version of that major version (for example, "~3"). When new versions for the same major version are available, they are automatically installed in the function app. To pin the app to a specific version, use the full version number (for example, "3.0.12345"). Default is "~3". A value of ~1 pins your app to version 1.x of the runtime. For more information, see Azure Functions runtime versions overview. A value of ~4 lets you run a preview version Azure Functions to use the .NET 6.0 preview. To learn more, see the Azure Functions v4 early preview page.

Key	Sample value
FUNCTIONS_EXTENSION_VERSION	`~3`

FUNCTIONS_V2_COMPATIBILITY_MODE

This setting enables your function app to run in a version 2.x compatible mode on the version 3.x runtime. Use this setting only if encountering issues when upgrading your function app from version 2.x to 3.x of the runtime.

Important

This setting is intended only as a short-term workaround while you update your app to run correctly on version 3.x. This setting is supported as long as the 2.x runtime is supported. If you encounter issues that prevent your app from running on version 3.x without using this setting, please report your issue.

Requires that FUNCTIONS_EXTENSION_VERSION be set to ~3.

Key	Sample value
FUNCTIONS_V2_COMPATIBILITY_MODE	`true`

FUNCTIONS_WORKER_PROCESS_COUNT

Specifies the maximum number of language worker processes, with a default value of 1. The maximum value allowed is 10. Function invocations are evenly distributed among language worker processes. Language worker processes are spawned every 10 seconds until the count set by FUNCTIONS_WORKER_PROCESS_COUNT is reached. Using multiple language worker processes is not the same as scaling. Consider using this setting when your workload has a mix of CPU-bound and I/O-bound invocations. This setting applies to all non-.NET languages.

Key	Sample value
FUNCTIONS_WORKER_PROCESS_COUNT	`2`

FUNCTIONS_WORKER_RUNTIME

The language worker runtime to load in the function app. This corresponds to the language being used in your application (for example, dotnet). Starting with version 2.x of the Azure Functions runtime, a given function app can only support a single language.

Key	Sample value
FUNCTIONS_WORKER_RUNTIME	`node`

Valid values:

Value	Language
`dotnet`	C# (class library) C# (script)
`dotnet-isolated`	C# (isolated process)
`java`	Java
`node`	JavaScript TypeScript
`powershell`	PowerShell
`python`	Python

MDMaxBackgroundUpgradePeriod

Controls the managed dependencies background update period for PowerShell function apps, with a default value of 7.00:00:00 (weekly).

Each PowerShell worker process initiates checking for module upgrades on the PowerShell Gallery on process start and every MDMaxBackgroundUpgradePeriod after that. When a new module version is available in the PowerShell Gallery, it's installed to the file system and made available to PowerShell workers. Decreasing this value lets your function app get newer module versions sooner, but it also increases the app resource usage (network I/O, CPU, storage). Increasing this value decreases the app's resource usage, but it may also delay delivering new module versions to your app.

Key	Sample value
MDMaxBackgroundUpgradePeriod	`7.00:00:00`

To learn more, see Dependency management.

MDNewSnapshotCheckPeriod

Specifies how often each PowerShell worker checks whether managed dependency upgrades have been installed. The default frequency is 01:00:00 (hourly).

After new module versions are installed to the file system, every PowerShell worker process must be restarted. Restarting PowerShell workers affects your app availability as it can interrupt current function execution. Until all PowerShell worker processes are restarted, function invocations may use either the old or the new module versions. Restarting all PowerShell workers completes within MDNewSnapshotCheckPeriod.

Within every MDNewSnapshotCheckPeriod, the PowerShell worker checks whether or not managed dependency upgrades have been installed. When upgrades have been installed, a restart is initiated. Increasing this value decreases the frequency of interruptions because of restarts. However, the increase might also increase the time during which function invocations could use either the old or the new module versions, non-deterministically.

Key	Sample value
MDNewSnapshotCheckPeriod	`01:00:00`

To learn more, see Dependency management.

MDMinBackgroundUpgradePeriod

The period of time after a previous managed dependency upgrade check before another upgrade check is started, with a default of 1.00:00:00 (daily).

To avoid excessive module upgrades on frequent Worker restarts, checking for module upgrades isn't performed when any worker has already initiated that check in the last MDMinBackgroundUpgradePeriod.

Key	Sample value
MDMinBackgroundUpgradePeriod	`1.00:00:00`

To learn more, see Dependency management.

PIP_EXTRA_INDEX_URL

The value for this setting indicates a custom package index URL for Python apps. Use this setting when you need to run a remote build using custom dependencies that are found in an extra package index.

Key	Sample value
PIP_EXTRA_INDEX_URL	`http://my.custom.package.repo/simple`

To learn more, see Custom dependencies in the Python developer reference.

PYTHON_ISOLATE_WORKER_DEPENDENCIES (Preview)

The configuration is specific to Python function apps. It defines the prioritization of module loading order. When your Python function apps face issues related to module collision (e.g. when you're using protobuf, tensorflow, or grpcio in your project), configuring this app setting to 1 should resolve your issue. By default, this value is set to 0. This flag is currently in Preview.

Key	Value	Description
PYTHON_ISOLATE_WORKER_DEPENDENCIES	`0`	Prioritize loading the Python libraries from internal Python worker's dependencies. Third-party libraries defined in requirements.txt may be shadowed.
PYTHON_ISOLATE_WORKER_DEPENDENCIES	`1`	Prioritize loading the Python libraries from application's package defined in requirements.txt. This prevents your libraries from colliding with internal Python worker's libraries.

PYTHON_ENABLE_WORKER_EXTENSIONS

The configuration is specific to Python function apps. Setting this to 1 allows the worker to load in Python worker extensions defined in requirements.txt. It enables your function app to access new features provided by third-party packages. It may also change the behavior of function load and invocation in your app. Please ensure the extension you choose is trustworthy as you bear the risk of using it. Azure Functions gives no express warranties to any extensions. For how to use an extension, please visit the extension's manual page or readme doc. By default, this value sets to 0.

Key	Value	Description
PYTHON_ENABLE_WORKER_EXTENSIONS	`0`	Disable any Python worker extension.
PYTHON_ENABLE_WORKER_EXTENSIONS	`1`	Allow Python worker to load extensions from requirements.txt.

PYTHON_THREADPOOL_THREAD_COUNT

Specifies the maximum number of threads that a Python language worker would use to execute function invocations, with a default value of 1 for Python version 3.8 and below. For Python version 3.9 and above, the value is set to None. Note that this setting does not guarantee the number of threads that would be set during executions. The setting allows Python to expand the number of threads to the specified value. The setting only applies to Python functions apps. Additionally, the setting applies to synchronous functions invocation and not for coroutines.

Key	Sample value	Max value
PYTHON_THREADPOOL_THREAD_COUNT	2	32

SCALE_CONTROLLER_LOGGING_ENABLED

This setting is currently in preview.

This setting controls logging from the Azure Functions scale controller. For more information, see Scale controller logs.

Key	Sample value
SCALE_CONTROLLER_LOGGING_ENABLED	`AppInsights:Verbose`

The value for this key is supplied in the format <DESTINATION>:<VERBOSITY>, which is defined as follows:

[!INCLUDE functions-scale-controller-logging]

SCM_LOGSTREAM_TIMEOUT

Controls the timeout, in seconds, when connected to streaming logs. The default value is 7200 (2 hours).

Key	Sample value
SCM_LOGSTREAM_TIMEOUT	`1800`

The above sample value of 1800 sets a timeout of 30 minutes. To learn more, see Enable streaming logs.

WEBSITE_CONTENTAZUREFILECONNECTIONSTRING

Connection string for storage account where the function app code and configuration are stored in event-driven scaling plans running on Windows. For more information, see Create a function app.

Key	Sample value
WEBSITE_CONTENTAZUREFILECONNECTIONSTRING	`DefaultEndpointsProtocol=https;AccountName=...`

Only used when deploying to a Premium plan or to a Consumption plan running on Windows. Not supported for Consumptions plans running Linux. Changing or removing this setting may cause your function app to not start. To learn more, see this troubleshooting article.

WEBSITE_CONTENTOVERVNET

A value of 1 enables your function app to scale when you have your storage account restricted to a virtual network. You should enable this setting when restricting your storage account to a virtual network. To learn more, see Restrict your storage account to a virtual network.

Key	Sample value
WEBSITE_CONTENTOVERVNET	`1`

Supported on Premium and Dedicated (App Service) plans (Standard and higher). Not supported when running on a Consumption plan.

WEBSITE_CONTENTSHARE

The file path to the function app code and configuration in an event-driven scaling plan on Windows. Used with WEBSITE_CONTENTAZUREFILECONNECTIONSTRING. Default is a unique string that begins with the function app name. See Create a function app.

Key	Sample value
WEBSITE_CONTENTSHARE	`functionapp091999e2`

Only used when deploying to a Premium plan or to a Consumption plan running on Windows. Not supported for Consumptions plans running Linux. Changing or removing this setting may cause your function app to not start. To learn more, see this troubleshooting article.

When using an Azure Resource Manager template to create a function app during deployment, don't include WEBSITE_CONTENTSHARE in the template. This application setting is generated during deployment. To learn more, see Automate resource deployment for your function app.

WEBSITE_DNS_SERVER

Sets the DNS server used by an app when resolving IP addresses. This setting is often required when using certain networking functionality, such as Azure DNS private zones and private endpoints.

Key	Sample value
WEBSITE_DNS_SERVER	`168.63.129.16`

WEBSITE_ENABLE_BROTLI_ENCODING

Controls whether Brotli encoding is used for compression instead of the default gzip compression. When WEBSITE_ENABLE_BROTLI_ENCODING is set to 1, Brotli encoding is used; otherwise gzip encoding is used.

WEBSITE_MAX_DYNAMIC_APPLICATION_SCALE_OUT

The maximum number of instances that the app can scale out to. Default is no limit.

Important

This setting is in preview. An app property for function max scale out has been added and is the recommended way to limit scale out.

Key	Sample value
WEBSITE_MAX_DYNAMIC_APPLICATION_SCALE_OUT	`5`

WEBSITE_NODE_DEFAULT_VERSION

Windows only. Sets the version of Node.js to use when running your function app on Windows. You should use a tilde (~) to have the runtime use the latest available version of the targeted major version. For example, when set to ~10, the latest version of Node.js 10 is used. When a major version is targeted with a tilde, you don't have to manually update the minor version.

Key	Sample value
WEBSITE_NODE_DEFAULT_VERSION	`~10`

WEBSITE_RUN_FROM_PACKAGE

Enables your function app to run from a mounted package file.

Key	Sample value
WEBSITE_RUN_FROM_PACKAGE	`1`

Valid values are either a URL that resolves to the location of a deployment package file, or 1. When set to 1, the package must be in the d:\home\data\SitePackages folder. When using zip deployment with this setting, the package is automatically uploaded to this location. In preview, this setting was named WEBSITE_RUN_FROM_ZIP. For more information, see Run your functions from a package file.

WEBSITE_TIME_ZONE

Allows you to set the timezone for your function app.

Key	OS	Sample value
WEBSITE_TIME_ZONE	Windows	`Eastern Standard Time`
WEBSITE_TIME_ZONE	Linux	`America/New_York`

[!INCLUDE functions-timezone]

WEBSITE_VNET_ROUTE_ALL

Indicates whether all outbound traffic from the app is routed through the virtual network. A setting value of 1 indicates that all traffic is routed through the virtual network. You need this setting when using features of Regional virtual network integration. It's also used when a virtual network NAT gateway is used to define a static outbound IP address.

Key	Sample value
WEBSITE_VNET_ROUTE_ALL	`1`

Next steps

Learn how to update app settings

See global settings in the host.json file

See other app settings for App Service apps

Files

functions-app-settings.md

Latest commit

History

functions-app-settings.md

File metadata and controls

App settings reference for Azure Functions

APPINSIGHTS_INSTRUMENTATIONKEY

APPLICATIONINSIGHTS_CONNECTION_STRING

AZURE_FUNCTION_PROXY_DISABLE_LOCAL_CALL

AZURE_FUNCTION_PROXY_BACKEND_URL_DECODE_SLASHES

AZURE_FUNCTIONS_ENVIRONMENT

AzureFunctionsJobHost__*

AzureWebJobsDashboard

AzureWebJobsDisableHomepage

AzureWebJobsDotNetReleaseCompilation

AzureWebJobsFeatureFlags

AzureWebJobsSecretStorageType

AzureWebJobsStorage

AzureWebJobs_TypeScriptPath

FUNCTION_APP_EDIT_MODE

FUNCTIONS_EXTENSION_VERSION

FUNCTIONS_V2_COMPATIBILITY_MODE

FUNCTIONS_WORKER_PROCESS_COUNT

FUNCTIONS_WORKER_RUNTIME

MDMaxBackgroundUpgradePeriod

MDNewSnapshotCheckPeriod

MDMinBackgroundUpgradePeriod

PIP_EXTRA_INDEX_URL

PYTHON_ISOLATE_WORKER_DEPENDENCIES (Preview)

PYTHON_ENABLE_WORKER_EXTENSIONS

PYTHON_THREADPOOL_THREAD_COUNT

SCALE_CONTROLLER_LOGGING_ENABLED

SCM_LOGSTREAM_TIMEOUT

WEBSITE_CONTENTAZUREFILECONNECTIONSTRING

WEBSITE_CONTENTOVERVNET

WEBSITE_CONTENTSHARE

WEBSITE_DNS_SERVER

WEBSITE_ENABLE_BROTLI_ENCODING

WEBSITE_MAX_DYNAMIC_APPLICATION_SCALE_OUT

WEBSITE_NODE_DEFAULT_VERSION

WEBSITE_RUN_FROM_PACKAGE

WEBSITE_TIME_ZONE

WEBSITE_VNET_ROUTE_ALL

Next steps