How to set Stack Settings for Azure Web App using Pulumi

A quick post on how to set Stack Settings for Azure Web App. While this setting is optional, it can cause unexpected behaviour.

For one of my projects, I was deploying an Azure Linux Web App using Pulumi. However, I could not set Stack as Node no matter what setting I set.

Azure and Pulumi documentation suggested that linuxFxVersion under siteConfig should set the Stack, but none of the values I provided (Node|20, ~20) worked.

Finally, this Azure CLI flag gave me the correct value which made it work.

az webapp list-runtimes --os linux

This will output something as below.

As you can see, the correct value for a NodeJS app is NODE:20-lts .

Setting that to linuxFxVersion will correctly configure the Azure Web App.

~/dev/pulumi/index.ts

That is it! This brief post is aimed at helping you save time by avoiding hours of trial and error :-)