Use x.CardinalityLimit directly

sdk/metric/internal/x/x.go

@@ -43,6 +43,9 @@ var (
 	//
 	// To enable this feature set the OTEL_GO_X_CARDINALITY_LIMIT environment
 	// variable to the integer limit value you want to use.
+	//
+	// Setting OTEL_GO_X_CARDINALITY_LIMIT to a value less than or equal to 0
+	// will disable the cardinality limits.
 	CardinalityLimit = newFeature("CARDINALITY_LIMIT", func(v string) (int, bool) {
 		n, err := strconv.Atoi(v)
 		if err != nil {

sdk/metric/pipeline.go

@@ -29,6 +29,7 @@ import (
 	"go.opentelemetry.io/otel/sdk/instrumentation"
 	"go.opentelemetry.io/otel/sdk/metric/internal"
 	"go.opentelemetry.io/otel/sdk/metric/internal/aggregate"
+	"go.opentelemetry.io/otel/sdk/metric/internal/x"
 	"go.opentelemetry.io/otel/sdk/metric/metricdata"
 	"go.opentelemetry.io/otel/sdk/resource"
 )
@@ -358,10 +359,15 @@ func (i *inserter[N]) cachedAggregator(scope instrumentation.Scope, kind Instrum
 	normID := id.normalize()
 	cv := i.aggregators.Lookup(normID, func() aggVal[N] {
 		b := aggregate.Builder[N]{
-			Temporality:      i.pipeline.reader.temporality(kind),
-			AggregationLimit: cardinalityLimit(),
+			Temporality: i.pipeline.reader.temporality(kind),
 		}
 		b.Filter = stream.AttributeFilter
+		// A value less than or equal to zero will disable the aggregation
+		// limits for the builder (an all the created aggregates).
+		// CardinalityLimit.Lookup returns 0 by default if unset (or
+		// unrecognized input). Use that value directly.
+		b.AggregationLimit, _ = x.CardinalityLimit.Lookup()
+
 		in, out, err := i.aggregateFunc(b, stream.Aggregation, kind)
 		if err != nil {
 			return aggVal[N]{0, nil, err}