VNET integration with multiple Azure Functions hosted on two App Service Plans

Cosmin Stirbu 156 Reputation points
2021-03-16T13:29:09.19+00:00

Hello,

I am looking for some guidance related to VNET and multiple Azure Functions hosted on two separate App Service Plans.

Initially my setup was the following:

1 VNET with one Subnet. This VNET has peering with another VNET where the database is hosted.
6 Azure Functions hosted on a single App Service Plan - each function is integrated with the VNET / Subnet

Using Terraform I migrated to the following setup:

1 VNET with one Subnet
4 Azure Functions hosted on a new App Service Plan - each function is integrated with the VNET / Subnet
2 Azure Functions hosted on a different new App Service Plan - each function is integrated with the VNET / Subnet

The initial App Service Plan was deleted.

Everything works as expected, however I have two concerns:

  1. The old App Service Plan is referenced on the subnet in serviceAssociationLinks
  2. Based on the documentation (https://learn.microsoft.com/en-us/azure/azure-functions/functions-networking-options) this new setup shouldn't work, so I'm confused if I should make any other changes or not:
    - The integration subnet can be used by only one App Service plan.
    - You can have only one regional VNet Integration per App Service plan. Multiple apps in the same App Service plan can use the same VNet.

Based on my concerns above, I'd like to understand if my new setup (2 App Service Plans and one VNET / Subnet) is working as expected / document or if it is working accidentally and I should make changes to it.

Thank you,
Cosmin

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