[exporter/datadog] Rename `metrics::send_monotonic_counter` to `metrics::sums::cumulative_monotonic_mode`

[mx-psi]

What will change?

The metrics::send_monotonic_counter setting from the Datadog exporter will be renamed to metrics::sums::cumulative_monotonic_mode, which will hold an enum. The setting name was taken from the Datadog OpenMetrics integration, but its meaning is confusing and it's not in a dedicated section for the metric name.

Who is affected?

You are affected if you explicitly set metrics::send_monotonic_counter on your Datadog exporter configuration. If you are affected, a warning will be logged stating that you are using it, together with a link to this issue.

Example warning:

Deprecated: "metrics::send_monotonic_counter" has been deprecated in favor of "metrics::sums::cumulative_monotonic_mode" and will be removed in v0.50.0. See github.com/open-telemetry/opentelemetry-collector-contrib/issues/8489 for details

The default behavior of the Datadog exporter will not change.

What should I do if I am affected?

Remove any references to metrics::send_monotonic_counter from your configuration and set metrics::sums::cumulative_monotonic_mode instead.

Example with metrics::send_monotonic_counter: true (click to expand)

If using:

# ...
exporters:
  datadog:
    api:
      key: ${DD_API_KEY}
    metrics:
      send_monotonic_counter: true
# ...

You can replace it by

# ...
exporters:
  datadog:
    api:
      key: ${DD_API_KEY}
    metrics:
      sums:
        cumulative_monotonic_mode: to_delta
# ...

Example with metrics::send_monotonic_counter: false (click to expand)

If using:

# ...
exporters:
  datadog:
    api:
      key: ${DD_API_KEY}
    metrics:
      send_monotonic_counter: false
# ...

You can replace it by

# ...
exporters:
  datadog:
    api:
      key: ${DD_API_KEY}
    metrics:
      sums:
        cumulative_monotonic_mode: raw_value
# ...

When will it change?

To be filled when this happens

Change description	Version of deprecation	Version of removal
Renaming of metrics::send_monotonic_counter	v0.48.0	v0.56.0

[mx-psi]

After internal discussion, we have decided to rename to cumulative_monotonic_mode instead of mode to be explicit. I have updated the name and description accordingly