Convert terraform to bicep

[nithinkumarkatta]

Is there any comprehensive blog or documentation available for converting entire Terraform code to Bicep, ensuring a smooth and issue-free migration? Additionally, what challenges should be considered when converting a large Azure infrastructure with more than 100 VMs?

[mattias-fjellstrom]

I don't think there is a tool for converting from Terraform to Bicep. What you can do is to export Bicep templates from the Azure portal for the infrastructure you want to start managing with Bicep.

Migrating from Terraform to Bicep is "easy" because you don't need to take care of migrating the state file. Once you have exported the Bicep templates from the portal you could start using them directly*. Just remember that if you use some sort of hybrid environment with both Bicep and Terraform you have to remove resources from the Terraform state files when you start managing them through Bicep.

• You will probably want to tidy the Bicep code before you start doing something with it

[nithinkumarkatta]

Any impact on current infrastructure while converting the terraform to bicep code & need any downtime ?

[mattias-fjellstrom]

@nithinkumarkatta No downtime.

However, the impact will depend a little bit on how large your current Terraform footprint is. Migrating from Terraform to Bicep can be as simple as:

1. Export all the resources as Bicep code from the Azure portal
2. Polish/clean the code (remove unnecessary default values, split into modules, etc)
3. Delete your Terraform source code and state file
4. Done

But if you need to do the migration in steps, where you will use both Terraform and Bicep in parallel, then you need to proceed with care. The general workflow will be something like:

1. Export a resource as Bicep code from the Azure portal
2. Remove the resource from your Terraform configuration (replace the resource with a data source if you still need to reference it elsewhere in Terraform) and add a removed block for that resource
3. Repeat until you don't have any more Terraform resources

Again, at no point during this is there any downtime required.