[exporters/datadog]: improve datadog_add_span_events

[ehsannm]

This is an Enhancement to the #2338.

Basically the current translation from open telemetry span events to span tags creates a big json string which really hard to read. Since datadog pretty the tags which are segmented with dots in the tag's name i suggested to have separate tags per event. Also for backward compatibility created a new config for it.

[linux-foundation-easycla]

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• ✅ login: ehsannm / name: Ehsan Noureddin Moosa (7aac4a9)

[mx-psi]

@gbbr (or someone else from APM) to review

[mx-psi]

Instead of using a string, let's create a new type alias like we do here:

opentelemetry-collector-contrib/exporter/datadogexporter/config/config.go

Lines 140 to 166 in 7aac4a9

	// CumulativeMonotonicSumMode is the export mode for OTLP Sum metrics.
	type CumulativeMonotonicSumMode string
	const (
	// CumulativeMonotonicSumModeToDelta calculates delta for
	// cumulative monotonic sum metrics in the client side and reports
	// them as Datadog counts.
	CumulativeMonotonicSumModeToDelta CumulativeMonotonicSumMode = "to_delta"
	// CumulativeMonotonicSumModeRawValue reports the raw value for
	// cumulative monotonic sum metrics as a Datadog gauge.
	CumulativeMonotonicSumModeRawValue CumulativeMonotonicSumMode = "raw_value"
	)
	var _ encoding.TextUnmarshaler = (*CumulativeMonotonicSumMode)(nil)
	// UnmarshalText implements the encoding.TextUnmarshaler interface.
	func (sm *CumulativeMonotonicSumMode) UnmarshalText(in []byte) error {
	switch mode := CumulativeMonotonicSumMode(in); mode {
	case CumulativeMonotonicSumModeToDelta,
	CumulativeMonotonicSumModeRawValue:
	*sm = mode
	return nil
	default:
	return fmt.Errorf("invalid cumulative monotonic sum mode %q", mode)
	}
	}

Also, wondering if we should have this on a traces::span_events section, and call it... tags_mapping?

[mx-psi]

Note that we are in the process of moving part of the code to the Datadog Agent (see #9693, pending stability of the pdata module) so it may take a little until this is mergeable

[gbbr]

I'll just leave a note here saying that we'll soon be looking into a better way to handle OpenTelemetry APM events at Datadog. Until then, I'd suggest not changing this to avoid breaking users even more

Lastly, indeed #9693 changes the code significantly to using what's in the Datadog Agent, but ultimately it should work out as the same behaviour. If we do decide to make this change, it should be made over there.

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[github-actions]

This PR was marked stale due to lack of activity. It will be closed in 14 days.

[github-actions]

Closed as inactive. Feel free to reopen if this PR is still being worked on.