Azure App Service

Azure App Service Plan is used to host apps like Azure Functions Apps, Azure Logic Apps and Azure Web App

Network Integration

Subnet Delegation is required to give the App Service Plan access to connect its apps to a subnet.

delegations = [{
    name    = "serverfarmsdelegation"
    sd_name = "Microsoft.Web/serverFarms"
    actions = ["Microsoft.Network/virtualNetworks/subnets/action"]
}]

Troubleshooting

Need to have settings in Configuration > Application Settings to get it to talk to the Azure Magic IP, as well as Networking > Outbound Traffic > VNet integration > Route All: Enabled

{
"name": "WEBSITE_DNS_ALT_SERVER",
"value": "168.63.129.16",
"slotSetting": false
},
{
"name": "WEBSITE_DNS_SERVER",
"value": "168.63.129.16",
"slotSetting": false
},