Verify compliant metric API specification implementation: Compatibility

[MrAlias]

• Identify all the normative requirements, recommendations, and options the specification defines as comments to this issue
• Ensure the current metric API implementation is compliant with these normative requirements, recommendations, and options in those comments.

[MrAlias]

All the metrics components SHOULD allow new APIs to be added to existing components without introducing breaking changes.

The term components is under-specified. I'm guessing this means that new method need to be able to be added to exported interfaces. This is something which we have documented as being a possibility¹ and therefore we comply with this suggestion.

Footnotes

1. https://github.com/open-telemetry/opentelemetry-go/pull/3441 ↩

[MrAlias]

All the metrics APIs SHOULD allow optional parameter(s) to be added to existing APIs without introducing breaking changes, if possible.

Our methods use variadic option parameters to support this.

opentelemetry-go/metric/meter.go

Line 37 in 75a19d1

Meter(instrumentationName string, opts ...MeterOption) Meter

opentelemetry-go/metric/meter.go

Lines 47 to 96 in 75a19d1

	Int64Counter(name string, options ...instrument.Int64Option) (syncint64.Counter, error)
	// Int64UpDownCounter returns a new instrument identified by name and
	// configured with options. The instrument is used to synchronously record
	// int64 measurements during a computational operation.
	Int64UpDownCounter(name string, options ...instrument.Int64Option) (syncint64.UpDownCounter, error)
	// Int64Histogram returns a new instrument identified by name and
	// configured with options. The instrument is used to synchronously record
	// the distribution of int64 measurements during a computational operation.
	Int64Histogram(name string, options ...instrument.Int64Option) (syncint64.Histogram, error)
	// Int64ObservableCounter returns a new instrument identified by name and
	// configured with options. The instrument is used to asynchronously record
	// increasing int64 measurements once per a measurement collection cycle.
	Int64ObservableCounter(name string, options ...instrument.Int64ObserverOption) (asyncint64.Counter, error)
	// Int64ObservableUpDownCounter returns a new instrument identified by name
	// and configured with options. The instrument is used to asynchronously
	// record int64 measurements once per a measurement collection cycle.
	Int64ObservableUpDownCounter(name string, options ...instrument.Int64ObserverOption) (asyncint64.UpDownCounter, error)
	// Int64ObservableGauge returns a new instrument identified by name and
	// configured with options. The instrument is used to asynchronously record
	// instantaneous int64 measurements once per a measurement collection
	// cycle.
	Int64ObservableGauge(name string, options ...instrument.Int64ObserverOption) (asyncint64.Gauge, error)
	// Float64Counter returns a new instrument identified by name and
	// configured with options. The instrument is used to synchronously record
	// increasing float64 measurements during a computational operation.
	Float64Counter(name string, options ...instrument.Float64Option) (syncfloat64.Counter, error)
	// Float64UpDownCounter returns a new instrument identified by name and
	// configured with options. The instrument is used to synchronously record
	// float64 measurements during a computational operation.
	Float64UpDownCounter(name string, options ...instrument.Float64Option) (syncfloat64.UpDownCounter, error)
	// Float64Histogram returns a new instrument identified by name and
	// configured with options. The instrument is used to synchronously record
	// the distribution of float64 measurements during a computational
	// operation.
	Float64Histogram(name string, options ...instrument.Float64Option) (syncfloat64.Histogram, error)
	// Float64ObservableCounter returns a new instrument identified by name and
	// configured with options. The instrument is used to asynchronously record
	// increasing float64 measurements once per a measurement collection cycle.
	Float64ObservableCounter(name string, options ...instrument.Float64ObserverOption) (asyncfloat64.Counter, error)
	// Float64ObservableUpDownCounter returns a new instrument identified by
	// name and configured with options. The instrument is used to
	// asynchronously record float64 measurements once per a measurement
	// collection cycle.
	Float64ObservableUpDownCounter(name string, options ...instrument.Float64ObserverOption) (asyncfloat64.UpDownCounter, error)
	// Float64ObservableGauge returns a new instrument identified by name and
	// configured with options. The instrument is used to asynchronously record
	// instantaneous float64 measurements once per a measurement collection
	// cycle.
	Float64ObservableGauge(name string, options ...instrument.Float64ObserverOption) (asyncfloat64.Gauge, error)

[MrAlias]

Every normative clause from this section of the v1.16.0 specification has been identified and our API has been validated that it complies. Closing.