Add env support for span limits configuration

CHANGELOG.md

@@ -8,6 +8,15 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 ## [Unreleased]
 
+- Added support to configure the span limits with environment variables.
+  The following environment variables are used. (#2606)
+  - `OTEL_SPAN_ATTRIBUTE_COUNT_LIMIT`
+  - `OTEL_SPAN_EVENT_COUNT_LIMIT`
+  - `OTEL_SPAN_LINK_COUNT_LIMIT`
+
+  If the provided environment variables are invalid (negative), the default values would be 
+  used. 
+
 ## [1.4.0] - 2022-02-11
 
 ### Added

sdk/internal/env/env.go

@@ -40,6 +40,21 @@ const (
 	// Note: Must be less than or equal to EnvBatchSpanProcessorMaxQueueSize
 	// i.e. 512
 	BatchSpanProcessorMaxExportBatchSizeKey = "OTEL_BSP_MAX_EXPORT_BATCH_SIZE"
+
+	// SpanAttributesCountKey
+	// Maximum allowed span attribute count
+	// Default: 128
+	SpanAttributesCountKey = "OTEL_SPAN_ATTRIBUTE_COUNT_LIMIT"
+
+	// SpanEventCountKey
+	// Maximum allowed span event count
+	// Default: 128
+	SpanEventCountKey = "OTEL_SPAN_EVENT_COUNT_LIMIT"
+
+	// SpanLinkCountKey
+	// Maximum allowed span link count
+	// Default: 128
+	SpanLinkCountKey = "OTEL_SPAN_LINK_COUNT_LIMIT"
 )
 
 // IntEnvOr returns the int value of the environment variable with name key if

sdk/trace/config.go

@@ -13,6 +13,7 @@
 // limitations under the License.
 
 package trace // import "go.opentelemetry.io/otel/sdk/trace"
+import "go.opentelemetry.io/otel/sdk/internal/env"
 
 // SpanLimits represents the limits of a span.
 type SpanLimits struct {
@@ -50,6 +51,12 @@ func (sl *SpanLimits) ensureDefault() {
 	}
 }
 
+func (sl *SpanLimits) parsePotentialEnvConfigs() {
+	sl.AttributeCountLimit = env.IntEnvOr(env.SpanAttributesCountKey, sl.AttributeCountLimit)
+	sl.LinkCountLimit = env.IntEnvOr(env.SpanLinkCountKey, sl.LinkCountLimit)
+	sl.EventCountLimit = env.IntEnvOr(env.SpanEventCountKey, sl.EventCountLimit)
+}
+
 const (
 	// DefaultAttributeCountLimit is the default maximum allowed span attribute count.
 	DefaultAttributeCountLimit = 128

sdk/trace/provider.go

@@ -366,6 +366,7 @@ func ensureValidTracerProviderConfig(cfg tracerProviderConfig) tracerProviderCon
 	if cfg.idGenerator == nil {
 		cfg.idGenerator = defaultIDGenerator()
 	}
+	cfg.spanLimits.parsePotentialEnvConfigs()
 	cfg.spanLimits.ensureDefault()
 	if cfg.resource == nil {
 		cfg.resource = resource.Default()

sdk/trace/provider_test.go

@@ -17,8 +17,14 @@ package trace
 import (
 	"context"
 	"errors"
+	"os"
 	"testing"
 
+	"github.com/stretchr/testify/require"
+
+	ottest "go.opentelemetry.io/otel/internal/internaltest"
+	"go.opentelemetry.io/otel/sdk/internal/env"
+
 	"github.com/stretchr/testify/assert"
 
 	"go.opentelemetry.io/otel/trace"
@@ -94,3 +100,39 @@ func TestSchemaURL(t *testing.T) {
 	tracerStruct := tracerIface.(*tracer)
 	assert.EqualValues(t, schemaURL, tracerStruct.instrumentationLibrary.SchemaURL)
 }
+
+func TestEnsureValidTracerProviderConfig(t *testing.T) {
+	envStore := ottest.NewEnvStore()
+	defer func() {
+		require.NoError(t, envStore.Restore())
+	}()
+	envStore.Record(env.SpanAttributesCountKey)
+	envStore.Record(env.SpanEventCountKey)
+	envStore.Record(env.SpanLinkCountKey)
+	require.NoError(t, os.Setenv(env.SpanEventCountKey, "111"))
+	require.NoError(t, os.Setenv(env.SpanAttributesCountKey, "222"))
+	require.NoError(t, os.Setenv(env.SpanLinkCountKey, "333"))
+	o := tracerProviderConfig{}
+	o = ensureValidTracerProviderConfig(o)
+	assert.Equal(t, 111, o.spanLimits.EventCountLimit)
+	assert.Equal(t, 222, o.spanLimits.AttributeCountLimit)
+	assert.Equal(t, 333, o.spanLimits.LinkCountLimit)
+}
+
+func TestEnsureValidTracerProviderConfigWithInvliadValue(t *testing.T) {
+	envStore := ottest.NewEnvStore()
+	defer func() {
+		require.NoError(t, envStore.Restore())
+	}()
+	envStore.Record(env.SpanAttributesCountKey)
+	envStore.Record(env.SpanEventCountKey)
+	envStore.Record(env.SpanLinkCountKey)
+	require.NoError(t, os.Setenv(env.SpanEventCountKey, "-111"))
+	require.NoError(t, os.Setenv(env.SpanAttributesCountKey, "222"))
+	require.NoError(t, os.Setenv(env.SpanLinkCountKey, "-333"))
+	o := tracerProviderConfig{}
+	o = ensureValidTracerProviderConfig(o)
+	assert.Equal(t, 128, o.spanLimits.EventCountLimit)
+	assert.Equal(t, 222, o.spanLimits.AttributeCountLimit)
+	assert.Equal(t, 128, o.spanLimits.LinkCountLimit)
+}