Terraform destroy fails on firewall delete "Error: deleting Azure Firewall Firewall"

[glennmusa]

Description

Running terraform destroy in AzureCloud from our pipeline agent fails with a 415 "The content media type '<null>' is not supported. Only 'application/json' is supported":

Error: deleting Azure Firewall Firewall: (Azure Firewall Name "firewall" / Resource Group "{resource group name}") : network.AzureFirewallsClient#Delete: Failure sending request: StatusCode=415 -- Original Error: Code="UnsupportedMediaType" Message="The content media type '<null>' is not supported. Only 'application/json' is supported."

Steps to Reproduce

Steps to reproduce the behavior:

1. Run the nightly Terraform AzureCloud pipeline

Expected behavior

The firewall is successfully deleted and the pipeline finishes the terraform destroy task.

Actual behavior

The firewall is not deleted, it and its parent resource group must be manually deleted, and the pipeline fails.

Additional context

The azurerm team also encounters this error: hashicorp/terraform-provider-azurerm#14907 (review)

For academic purposes, it reads like this is the method bubbling up the error: https://github.com/hashicorp/terraform-provider-azurerm/blob/67e95001cc7ed859f2bd589c426f4e5bc056d237/vendor/github.com/Azure/azure-sdk-for-go/services/network/mgmt/2021-05-01/network/azurefirewalls.go#L145-L149

Operating System: ubuntu
Terraform Version: 1.13 and azurerm 2.90.0
Cloud (public, Azure Government, etc.): AzureCloud

[glennmusa]

The firewall is now able to be destroyed successfully.

[glennmusa]

This error has returned.

[brooke-hamilton]

Should we change the cleanup to delete the resource groups and subscription-level diagnostic settings?

[glennmusa]

^ I think it's a good idea as long as the "nightly status" still shows failure if the Terraform commands are unable to round-trip creation and deletion. Could put it in another always run job in the existing pipeline.

Oops, I misunderstand! You bring up a good point. What are we testing by running terraform destroy? Not our implementation, but the destroy command. I'm happy to replace the destroy step with a manual, Azure-y cleanup.

[brooke-hamilton]

I will convert this to a backlog item that will implement resource group deletes.

[brooke-hamilton]

Created #640 to replace this bug.