template.json

{
    "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
    "contentVersion": "1.0.0.0",
    "parameters": {
        "appServiceName": {
            "type": "String",
            "metadata": {
                "description": "Name for the App Service"
            }
        },
        "location": {
            "type": "String",
            "metadata": {
                "description": "Location for resource."
            }
        },
        "appServicePlanID": {
            "type": "String",
            "metadata": {
                "description": "Resource ID of the App Service Plan"
            }
        },
        "principalId": {
            "defaultValue": "",
            "type": "String",
            "metadata": {
                "description": "User Asisgned Identity for App Service"
            }
        },
        "appSettings": {
            "defaultValue": {},
            "type": "Object",
            "metadata": {
                "description": "App Settings for the Application"
            }
        }
    },
    "resources": [
        {
            "type": "Microsoft.Web/sites",
            "apiVersion": "2022-03-01",
            "name": "[toLower(format('app-{0}', parameters('appServiceName')))]",
            "location": "[parameters('location')]",
            "tags": {
                "displayName": "Website"
            },
            "identity": "[if(empty(parameters('principalId')), createObject('type', 'SystemAssigned'), createObject('type', 'SystemAssigned, UserAssigned', 'userAssignedIdentities', createObject(format('{0}', parameters('principalId')), createObject())))]",
            "properties": {
                "serverFarmId": "[parameters('appServicePlanID')]",
                "httpsOnly": true,
                "siteConfig": {
                    "minTlsVersion": "1.2",
                    "appSettings": [
                        "[parameters('appSettings')]"
                    ]
                }
            }
        },
        {
            "type": "Microsoft.Web/sites/config",
            "apiVersion": "2022-09-01",
            "name": "[format('{0}/{1}', toLower(format('app-{0}', parameters('appServiceName'))), 'appsettings')]",
            "dependsOn": [
                "[resourceId('Microsoft.Web/sites', toLower(format('app-{0}', parameters('appServiceName'))))]"
            ],
            "properties": "[parameters('appSettings')]"
        }
    ],
    "outputs": {
        "appServiceManagedIdentity": {
            "type": "String",
            "value": "[reference(resourceId('Microsoft.Web/sites', toLower(format('app-{0}', parameters('appServiceName')))), '2022-09-01', 'full').identity.principalId]"
        },
        "appServiceName": {
            "type": "String",
            "value": "[toLower(format('app-{0}', parameters('appServiceName')))]"
        }
    }
}