I have one app service in Azure in a particular region with 5 outbound ip addresses and a second in the same region but there are 20 outbound ip addresses , which doesnt look right. One app is Premiumv2 the other is Premium V3 What determines the outbound ip addresses and the additional outbound ip addresses and can an outbound ip addresse be added by a user ?

CodePudding user response：

App Service is a multi-tenant service (unless you use App Service Environments) and this service consists of gateway servers which accept the initial requests to App Services and forward them on to worker instances where your code actually lives. Those workers are the App Service Plans which are deployed to specific deployment units each of which are assigned a single inbound IP and multiple outbound IPs, the latter of which are chosen at random at runtime when an outbound request takes place.

This document covers all of the above and more about App Service IP addresses.

Based on which deployment unit your apps end up on you will get different IP addresses, also the SKU can affect the number of IP addresses as you've seen. If you scale up/down or redploy apps you can end up getting new IPs, the above doc has the full set of conditions as to when this might happen.

Depending on what you need to do you could consider using an App Service Environment which has single static IPs for inbound and outbound:

IP addresses don't change, as long as your App Service Environment is running

You can also use App Service VNET connectivity to give you App a private IP in a VNET so that you can connect it to resources privately in the VNET using private endpoints.