End-to-End Analytics Platform – Bicep What-If deployment

This is part of my series on learning to build an End-to-End Analytics Platform project.

TLDR; After I refactored my code to use modules I found that Bicep supports ‘What-If’ operations which explain what the code is going to do before deploying it. This post I do a short test on that. Found an issue not showing Azure Synapse resource creation. Then browsed the Bicep GitHub repo to search issues related to What-If operations. Didn’t find what I was hoping for, so logged my first public GitHub issue 😁.

Update: The issue we encountered seems to be related to another preflight improvement which is being worked on but is a “…bit of a gnarly, low level issue so please be patient πŸ™‚. I was amazed to see how quickly Bicep the team responded on this.

What happens when I push this button? πŸ€”

So after my previous post on factoring in some Bicep best practices for code reuse I noticed that Bicep supports ‘What-If’ operations.

az deployment sub create --name '<name of deployment>' --location '<location name>' --template-file '<path to bicep file>' --confirm-with-what-if

Side note: I had to change the VS Code theme to save us all from the agony of lime green on light grey background reading.

What’s nice is we get a breakdown of changes that we are about to apply to our environment. I think that is awesome.

Terminal output of a Bicep deployment what-if operation.
I have one question. Explosions? 🧨

Yes, for the eagle-eyed reader, I realised my storage account name is an Azure Region name hahaha πŸ˜‚

Looking at the terminal output, reading top to bottom, I can see:

  • We are about to deploy at the subscription scope.
  • We are deploying a Azure Data Lake Gen2 Storage Account with blob container and all their configuration goodness.
  • We are deploying an Azure Synapse… wait a minute…

What was weird was that I didn’t see the Synapse Workspace. I checked the deployment details/output and it was there.

Azure portal deployments screen.

I wondered if the reason it didn’t output the Azure Synapse Resource during the What-If was because I didn’t define any output variables for it which I did for the storage account.

Bicep output code.
Putting more out.

I updated my variables, added output variables for my synapse.bicep module, then ran the What-If again. Aaaaand…. nothing changed. Considering Bicep is an Open Source project on GitHub we get to search for issues with ‘What-If’ operations. So, we get to create a issue 😁 Taking the things learnt over the past few posts on

GitHub issue summary.
de bug πŸ›

That’s it. Done. Created our first public issue: what-if operation doesn’t seem to include all bicep defined or created resources Β· Issue #3682 Β· Azure/bicep (github.com).

The what-if behaviour doesn’t block us at this stage. The deployment works so at this point I think we are set for the next section to work on getting this into a GitHub Actions pipeline.


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