Having the Terraform azure state file under different subscription

[Joshua Falken]

To manage Terraform state files across multiple Azure subscriptions, you need to ensure that the Terraform process has the necessary permissions to access the storage account where the state file is located, regardless of the subscription under which the resources are being deployed.

The error message you’re encountering indicates that the Terraform process does not have the necessary permissions to access the storage account in the sub-dev subscription when you’re operating under the sub-prod subscription context.

Here are some steps you can take to resolve this issue:

1. Service Principal Authentication: Create a Service Principal with access to both subscriptions. This Service Principal should have the necessary permissions to read and write to the storage account in sub-dev. You can then configure Terraform to use this Service Principal for authentication by setting the ARM_CLIENT_ID, ARM_CLIENT_SECRET, ARM_SUBSCRIPTION_ID, and ARM_TENANT_ID environment variables.

2. Storage Account Access: Ensure that the Service Principal has the “Storage Blob Data Contributor” role assigned for the storage account in the sub-dev subscription. This can be done in the Azure Portal or using Azure CLI with the following command:

   az role assignment create --assignee <Service-Principal-AppId> --role "Storage Blob Data Contributor" --scope /subscriptions/sub-dev/resourceGroups/rg-dev/providers/Microsoft.Storage/storageAccounts/tfstate

3. Terraform Backend Configuration: Configure the Terraform backend to use the Service Principal credentials. You can specify the subscription_id in the backend configuration to explicitly set which subscription the backend should use:

   terraform {
     backend "azurerm" {
       subscription_id      = "sub-dev"
       resource_group_name  = "rg-dev"
       storage_account_name = "tfstate"
       container_name       = "tfcontainer"
       key                  = "terraform.tfstate"
     }
   }

4. Workspace-Specific Configuration: Since you are using Terraform workspaces, you can specify workspace-specific configuration for the backend using partial configuration and passing the workspace-specific variables during the terraform init command.

Here’s an example of how you might pass the subscription ID when initializing Terraform for a specific workspace:

terraform init -backend-config="subscription_id=sub-dev"

By following these steps, you should be able to manage your Terraform state file across multiple Azure subscriptions without encountering access errors.

The retrieved documents do not provide a direct solution to your problem, as they focus on manual deployment steps for SAP Library, infrastructure deployment, creating and configuring Azure DDoS Network Protection, enabling monitoring for Kubernetes clusters, and creating policy assignments . However, the principles of Terraform state management and Azure role assignments are relevant to your situation.