Bring your own functions to Azure Static Web Apps
Azure Static Web Apps APIs are supported by two possible configurations: managed functions and bring your own functions. For more information on the differences in configurations, see the overview.
This article demonstrates how to link an existing Azure Functions app to an Azure Static Web Apps resource.
Bring your own functions is only available in the Azure Static Web Apps Standard plan.
Consider an existing Azure Functions app that exposes an endpoint via the following location.
Once linked, you can access that same endpoint through the
api path from your static web app, as shown in this example URL.
Both endpoint URLs point to the same function.
Link an existing Azure Functions app
Before you associate an existing Functions app, you first need to adjust to configuration of your static web app.
api_locationvalue to an empty string (
"") in the workflow configuration file.
Open your Static Web Apps instance in the Azure portal.
From the Settings menu, select APIs.
From the Production row, select Link to open the Link new Backend window.
Enter the following settings.
Setting Value Backed resource type Select Function App. Subscription Select your Azure subscription name. Resource name Select the Azure Functions app name.
The Azure Functions app is now mapped to the
/api route of your static web app.
Make sure to set the
api_location value to an empty string (
"") in the workflow configuration file before you link an existing Functions application. Also, calls assume that the external function app retains the default
api route prefix. Many apps remove this prefix in the host.json. Make sure the prefix is in place in the configuration, otherwise the call fails.
You're responsible for setting up a deployment workflow for your Azure Functions app.
Authentication and authorization: If authentication and authorization policies aren't already set up on your existing Functions app, then the static web app has exclusive access to the API. To make your Functions app accessible to other applications, add another identity provider or change the security settings to allow unauthenticated access.
If you enable authentication and authorization in your linked Functions app, it must use Azure App Service Authentication and authorization provider version 2.
Required public accessibility: An existing Functions app needs to not apply the following security configurations.
- Restricting the IP address of the Functions app.
- Restricting traffic through private link or service endpoints.
Function access keys: If your function requires an access key, then you must provide the key with calls from the static app to the API.
- Only one Azure Functions app is available to a single static web app.
api_locationvalue in the workflow configuration must be set to an empty string.
- Not supported in Static Web Apps pull request environments.
- While your Azure Functions app may respond to various triggers, the static web app can only access functions via Http endpoints.
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