Custom traces, over different `dagger run`

[leaden moat]

Is it possible to start a trace in one dagger run and complete it in another?

Context, we have a bunch of Jenkins subjobs that are building components, each with their own dagger run and traces.

1. I'd like to have a global trace that starts at the beginning of our top-level job
2. Later, it then sends a pass/fail based on the full build tree, using another call to dagger run

bonus points if I can tie all the subbuilds to the global trace

[main python]

That's currently not possible unfortunately as a cloud trace is currently scoped as a single dagger call / run. cc @charred roost

[charred roost]

If you have the trace + root span ID of one trace, you could technically create a span link (https://opentelemetry.io/docs/concepts/signals/traces/#span-links) from a custom span pointing back to it. But Cloud won't do anything special with that at the moment.

(Mostly from lack of use case, so this may be an interesting one)

[leaden moat]

This is from thinking about our migration strategy. At some point, we could ideally send them to Dagger UI first, instead of Jenkins/Argo UI, when we get those systems down to just running dagger pipelines.

Today, we have a top-level job that forms the root of the build tree. We do some pre/post tasks here, like send BBC notifications and calc some build-wide config we pass to all subjobs