Discover App Service networking features

  • 3 minutes

By default, apps hosted in App Service are accessible directly through the internet and can reach only internet-hosted endpoints. But for many applications, you need to control the inbound and outbound network traffic.

There are two main deployment types for Azure App Service. The multitenant public service hosts App Service plans in the Free, Shared, Basic, Standard, Premium, PremiumV2, and PremiumV3 pricing SKUs. There's also the single-tenant App Service Environment (ASE) hosts Isolated SKU App Service plans directly in your Azure virtual network.

Multi-tenant App Service networking features

Azure App Service is a distributed system. The roles that handle incoming HTTP or HTTPS requests are called front ends. The roles that host the customer workload are called workers. All the roles in an App Service deployment exist in a multi-tenant network. Because there are many different customers in the same App Service scale unit, you can't connect the App Service network directly to your network.

Instead of connecting the networks, you need features to handle the various aspects of application communication. The features that handle requests to your app can't be used to solve problems when you're making calls from your app. Likewise, the features that solve problems for calls from your app can't be used to solve problems to your app.

Inbound features Outbound features
App-assigned address Hybrid Connections
Access restrictions Gateway-required virtual network integration
Service endpoints Virtual network integration
Private endpoints

You can mix the features to solve your problems with a few exceptions. The following inbound use cases are examples of how to use App Service networking features to control traffic inbound to your app.

Inbound use case Feature
Support IP-based SSL needs for your app App-assigned address
Support unshared dedicated inbound address for your app App-assigned address
Restrict access to your app from a set of well-defined addresses Access restrictions

Default networking behavior

Azure App Service scale units support many customers in each deployment. The Free and Shared SKU plans host customer workloads on multitenant workers. The Basic and higher plans host customer workloads that are dedicated to only one App Service plan. If you have a Standard App Service plan, all the apps in that plan run on the same worker. If you scale out the worker, all the apps in that App Service plan are replicated on a new worker for each instance in your App Service plan.

Outbound addresses

The worker VMs are broken down in large part by the App Service plans. The Free, Shared, Basic, Standard, and Premium plans all use the same worker VM type. The PremiumV2 plan uses another VM type. PremiumV3 uses yet another VM type. When you change the VM family, you get a different set of outbound addresses.

There are many addresses that are used for outbound calls. The outbound addresses used by your app for making outbound calls are listed in the properties for your app. These addresses are shared by all the apps running on the same worker VM family in the App Service deployment. If you want to see all the addresses that your app might use in a scale unit, there's a property called possibleOutboundIpAddresses that lists them.

Find outbound IPs

To find the outbound IP addresses currently used by your app in the Azure portal, select Properties in your app's left-hand navigation.

You can find the same information by running the following Azure CLI command in the Cloud Shell. They're listed in the Additional Outbound IP Addresses field.

az webapp show \
    --resource-group <group_name> \
    --name <app_name> \ 
    --query outboundIpAddresses \
    --output tsv

To find all possible outbound IP addresses for your app, regardless of pricing tiers, run the following command in the Cloud Shell.

az webapp show \
    --resource-group <group_name> \ 
    --name <app_name> \ 
    --query possibleOutboundIpAddresses \
    --output tsv