unexpected print statement from ConsoleMetricExporter

[codeboten]

Describe your environment
I was writing an example application and forgot to set the meter provider. Running the code resulted in output bring printed, which led me in a rabbit hole of trying to figure out why my metrics weren't being produced, when in fact I'd missed the important step of using the MeterProvider.

Note this behaviour is different from the ConsoleSpanExporter which doesn't print any output if it's not used.

Steps to reproduce
Run the following code:

from opentelemetry.sdk.metrics import MeterProvider
from opentelemetry.sdk.metrics.export import (
    ConsoleMetricExporter,
    PeriodicExportingMetricReader,
)

reader = PeriodicExportingMetricReader(ConsoleMetricExporter())
provider = MeterProvider(metric_readers=[reader])

What is the expected behavior?
Since I did not configure or use the provider in anyway, I was expecting not to see anything.

What is the actual behavior?

The following printed:

{"resource_metrics": [{"resource": {"attributes": {"telemetry.sdk.language": "python", "telemetry.sdk.name": "opentelemetry", "telemetry.sdk.version": "1.17.0.dev0", "service.name": "unknown_service"}, "schema_url": ""}, "scope_metrics": [], "schema_url": ""}]}

Additional context
Add any other context about the problem here.

[aabmass]

Since I did not configure or use the provider in anyway, I was expecting not to see anything.

I've also noticed this. @codeboten do you think one way is "correct" or incorrect? It is kind of spammy that it flushes an "empty" resource metrics but OTOH it is pretty clear to the exporter that the SDK was created with no instruments or measurements taken.

Idr if there is anything in the data model/spec differentiating these cases.

[codeboten]

@aabmass I think since the provider wasn't actually being used anywhere, it is incorrect to emit anything.

It wasn't immediately clear to me that I'd misconfigured my application and had forgotten to use the meter provider. I created instruments and measured things, but since i wasn't using the right provider to get the meter, my emitted data was empty.