Bicep and Azure Resource Manager (ARM) are able to dispense with state only because every Azure resource is required to be individually addressable and to report its state in a consistent way, and each resource is expected to support fully idempotent creation operations. The state information is still there, but it's stored on the resource itself.
Bicep/ARM still has issues with resource deletion, though. The default deployment behavior is to ignore resources that aren't described in a deployment template, so if you remove a VM from your template and redeploy, the VM will keep running until you manually delete it. There are a couple ways around this issue, but they all rely on having state external to the resource itself.
Disclaimer: I work on Bicep/ARM and think it's pretty great, but it's not perfect.
Re:Terraform should have remained stateless
by janosdebugs on Saturday May 28, 2022 @03:48AM
(#31538421)
Not every provider supports tags, or they don't support it for all resources. Sure, if you only use AWS this may be a solution, but not for everyone.
Regarding the state, it took me a very long time to come up with good organization for my code, but it works once you've gotten used to it. I really only need to mess with state files when there is a bug in the provider like the aforementioned GitHub issue.
One problem, as mentioned in a sibling comment, is if you don't have state then how do you know a resource has been deleted? One other option might be a system that compares the "desired state" from the previous version of the config. That might be an interesting approach - keeping a history of config. But that is, of course, state :)
I use TF a bit. I want to like it, but I do spend inordinate amounts of time faffing around with state files to make them match reality, and I'm not even doing particularly complex stuff. I'm told other tooling (eg: Bicep for Azure) dispenses with state entirely.