[Observability discussion] How do we untangle our dependencies between plugins?

[jasonrhodes]

@smith and @weltenwort, I know you two have thought about this a lot already. Primarily, we need to untangle our dependencies between each of our plugins because of Typescript, but I think it's a good idea to do this work for lots of reasons. 

I'd just like to make sure we have a somewhat consistent way to manage breaking out shared pieces of our apps so that they can be imported across other Kibana plugins without causing complex dependency trees that risk accidental circular dependencies. Can we start a conversation about the different options for solving this here in this issue?

For instance, we've discussed breaking our various apps into multiple plugins, e.g. "logs-shared" and "logs-app", and require that all deps flow from shared to app. In this model, we would only export deps for others from our "-shared" apps.

Also pinging @elastic/logs-metrics-ui @elastic/apm-ui @elastic/uptime @elastic/kibana-core @elastic/kibana-stack-services for any context anyone on those teams can provide for how to best handle this.

[pgayvallet]

For instance, we've discussed breaking our various apps into multiple plugins, e.g. "logs-shared" and "logs-app", and require that all deps flow from shared to app

That's the most common adopted pattern when there are some bi-directional dependencies between 2 plugins

e.g

appA -> appB
appB -> appA

=>

appA -> commonA, commonB
appB -> commonA, commonB

[smith]

Adding TS project references will be a big help here, since currently dependencies between plugins are tracked through kibana.json, which is basically a guess, as I've discovered quite a few dependencies that weren't declared in those files.

#81003 is where we're tracking this migration in APM. I'm working through the tree of dependencies, currently working on the observability plugin and its dependencies.

From what I can tell so far, we're not in too bad of a state, and I don't foresee any big problems untangling our existing circular dependencies. I feel like right now it's a problem of visibility and once that's resolved a few minor untangling tasks need to happen.

Once all that's taken care of, the suggestions above should be sufficient and I'd be open to any methods we can come up with together to keep it clean.