Disabled JetStream Assets

[ripienaar]

Proposed change

When a stream is disabled we should start a placeholder that sits on the ingest subjects and report itself as disabled to INFO and other calls.

We have many reasons a stream can become disabled:

• It's broken, corrupt etc
• It requires feature level n while the server trying to start it can only offer <n such as during rollbacks

We'd during this look at adding the downgrade safety features from ADR-44 around feature levels. This avoids the problem where today downgrading will potentially start an assets without required features and essentially corrupt the data and configuration.

Apart from obvious visibility and user support features this will also fix a shortcoming we have today where if a stream is down a new stream can be created that sits on its subject. If that stream later recovers there would be a clash causing problems.

The stream / consumer info should have a new field that indicates is down and why.
Interacting with these streams / consumers for anything but INFO should cause errors, this includes publishing to them

Use case

Data safety and user visibility of issues caused by downgrades etc

Contribution

No response