I've got a PR opened to implement this but due to S3 CAP limitations, it hasn't been merged. The current state is that it could be merged for non-S3 backends and a DynamoDB type lock could be added for S3 backends. I don't have much interest to keep pushing it forward (its been nearly a year of "ill get back to you next week") although their new VP has been more responsive.

Alternately I was considering just implementing the server API to do state storage & locking, but we have implemented some workarounds that are good enough for now.

I just want to say thanks for your initiative on opening https://github.com/pulumi/pulumi/pull/2697. (I've seen you active on a few other issues and in the Slack channel too)

I think it's really unfortunate (whatever the reason) that the team was this slow to provide meaningful feedback on the PR.

This was true when it was first released, but they now allow you to bring your own backend store.

https://www.pulumi.com/docs/intro/concepts/state/

That page lists this as a feature of their service, implying it isn't available in other backend stores:

Concurrent state locking to prevent corrupting your infrastructure state in a team environment

It's specifically the state-locking feature that's missing from 3rd party backends.