Adds Nats-Schedule-Rollup to schedules

[ripienaar]

Relates to nats-io/nats-server#7557

[ripienaar]

A bit non ideal since we can't detect this is happening on older servers, so maybe we should also add a thing where we check Nats-Schedule-* on the schedule messages and ensure we do not get any headers the current server dont support, that sets us up to expand this in future and inform users if they use a too old version, wdyt @MauriceVanVeen

[MauriceVanVeen]

LGTM

[MauriceVanVeen]

A bit non ideal since we can't detect this is happening on older servers, so maybe we should also add a thing where we check Nats-Schedule-* on the schedule messages and ensure we do not get any headers the current server dont support, that sets us up to expand this in future and inform users if they use a too old version, wdyt @MauriceVanVeen

We do already strip Nats-Schedule-* headers when publishing the delayed message, so at least this new header doesn't end up there. Only thing that will happen now is that a server would not recognize this, and silently ignore. Although not the best, I think this is fine for now and we should look at this from a broader perspective when we get to the feature flags work. This could then do proper acknowledging that all servers support a feature and error otherwise, etc.

[ripienaar]

Although not the best, I think this is fine for now and we should look at this from a broader perspective when we get to the feature flags work. This could then do proper acknowledging that all servers support a feature and error otherwise, etc.

Ok so we just silently fail for now? We have no idea how long feature flags work will take, and then we would have to check them anyway right?

Getting the check into 2.12.x might help?

[MauriceVanVeen]

Getting the check into 2.12.x might help?

We could add detection of unknown NATS headers in nats-io/nats-server#7454. There we scan through all the headers and could error if we see an unknown suffix. But that's currently also reserved for 2.14, although we could perhaps backport if we'd like.

[ripienaar]

Getting the check into 2.12.x might help?

We could add detection of unknown NATS headers in nats-io/nats-server#7454. There we scan through all the headers and could error if we see an unknown suffix. But that's currently also reserved for 2.14, although we could perhaps backport if we'd like.

not sure we can back port all the things there but yeah looking at the schedule code I can see how handling it there is a pain, will think