azure-arm builder does not allow subscription_id selection when using managed identity authentication

[dougbw]

Overview of the Issue

Currently it is impossible to specify a subscription_id when using managed identity authentication, as when only subscription_id is provided packer assumes an interactive login is desired.

In our case we need the base images to be stored in a different subscription to on running our CI/CD pipeline build agents. A single managed identity can have access to many Azure subscriptions.

Reproduction Steps

• Create a user assigned managed identity
• Grant the identity Azure RBAC permissions to multiple subscriptions
• Assign the managed identity to a vm
• On the vm execute az login --identity and you should see output for multiple subscriptions
• Provide a subscription_id to the azure-arm builder in packer and you will be stuck on an interactive login

[amarkulis]

Is there a work around for this? This makes using managed identities impossible because every result returns: "Cannot locate the managed image resource group"

[ghost]

This issue has been automatically migrated to hashicorp/packer-plugin-azure#29 because it looks like an issue with that plugin. If you believe this is not an issue with the plugin, please reply to hashicorp/packer-plugin-azure#29.