Vector: Vector should shut down when stdin is closed and it's the only source

[lukesteensen]

Logically, if the only source in a vector topology is stdin and the process's STDIN has been closed, Vector should finish processing all the existing events in the pipeline and gracefully shutdown since there is no possibility for further events.

I can't quite tell why, but this is not the current behavior. The stdin source itself seems to finish properly, and I would expect that the close of its channel would cause that to cascade through all the downstream components. It's possible we're retaining an additional Sender for the connecting channels somewhere, maybe to support config reloading?

[binarylogic]

@stbrody if we decide to proceed with the "Simplify Shutdown" project this issue is related.

[Hoverbear]

Should vector shut down if all sources are closed?

[lukesteensen]

Should vector shut down if all sources are closed?

I think so, with the caveat that most sources probably can't be "closed" in the way that stdin can. Servers, for example, can't know that they'll never receive another connection.

[binarylogic]

Just adding a note. I want to make sure this does not shut down Vector when the config is reloaded.