spanmetrics: wire in new metrics_flush_interval field

[tpaschalis]

Request

Since we've updated our OpenTelemetry Collector dependency, we can now wire in a new field available in the spanmetrics processor, metrics_flush_interval.

Use case

This would help with limiting the rate of metrics generation, from every time a trace was received to a preset interval and help users manage their data throughput.

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[rfratto]

Is this for both Flow mode and static mode?

[shelbyatgrafana]

@rfratto I believe this is just for static mode if I recall correctly.

I am not sure about flow mode, but if you make any changes to the static agent, please keep me updated.

[foreverest]

Hey @rfratto @shelbyatgrafana . I'm the one who raised this. We use static mode, currently.

[rfratto]

For development context, anything added to static mode must also be brought into flow mode, since we're actively working on giving flow mode parity with static mode.

Since the request is for static mode, then the implementation must make sure that both static mode and flow mode are covered.

[nijave]

I think this was added here 7357b37#diff-e2e63ff69ed7490ea189f8053e03be8b6d74504e8b1f8ec5b4c516e07b9daf28R50 ? (in 0.36.1)

Edit: Looks like maybe this only exists in flow mode, not static mode

[ptodev]

Flow mode already supports metrics_flush_interval in otelcol.connector.spanmetrics.

During the last time we upgraded our Otel dependencies, I made a conscious decision to refrain from adding new config parameters to Otel components used in Static mode. This was based on the assumption that the components would keep working as they have in the past, and any new parameters would be set to default values by Otel so that components keep working as before. To be honest this assumption is hard to verify, given that #5271 is causing inconvenience for users I will look into adding the metrics_flush_interval config parameter, and will potentially check if other parameters need to be added as well. I think it's likely that #5271 is a missing feature and not a bug, but it shouldn't be too much effort to add it in and improve the customer experience.