97 lines
3.2 KiB
Go
97 lines
3.2 KiB
Go
// Copyright The OpenTelemetry Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package x contains support for OTel metric SDK experimental features.
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//
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// This package should only be used for features defined in the specification.
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// It should not be used for experiments or new project ideas.
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package x // import "go.opentelemetry.io/otel/sdk/metric/internal/x"
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import (
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"os"
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"strconv"
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"strings"
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)
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var (
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// Exemplars is an experimental feature flag that defines if exemplars
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// should be recorded for metric data-points.
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//
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// To enable this feature set the OTEL_GO_X_EXEMPLAR environment variable
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// to the case-insensitive string value of "true" (i.e. "True" and "TRUE"
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// will also enable this).
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Exemplars = newFeature("EXEMPLAR", func(v string) (string, bool) {
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if strings.ToLower(v) == "true" {
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return v, true
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}
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return "", false
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})
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// CardinalityLimit is an experimental feature flag that defines if
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// cardinality limits should be applied to the recorded metric data-points.
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//
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// To enable this feature set the OTEL_GO_X_CARDINALITY_LIMIT environment
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// variable to the integer limit value you want to use.
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//
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// Setting OTEL_GO_X_CARDINALITY_LIMIT to a value less than or equal to 0
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// will disable the cardinality limits.
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CardinalityLimit = newFeature("CARDINALITY_LIMIT", func(v string) (int, bool) {
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n, err := strconv.Atoi(v)
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if err != nil {
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return 0, false
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}
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return n, true
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})
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)
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// Feature is an experimental feature control flag. It provides a uniform way
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// to interact with these feature flags and parse their values.
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type Feature[T any] struct {
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key string
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parse func(v string) (T, bool)
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}
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func newFeature[T any](suffix string, parse func(string) (T, bool)) Feature[T] {
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const envKeyRoot = "OTEL_GO_X_"
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return Feature[T]{
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key: envKeyRoot + suffix,
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parse: parse,
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}
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}
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// Key returns the environment variable key that needs to be set to enable the
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// feature.
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func (f Feature[T]) Key() string { return f.key }
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// Lookup returns the user configured value for the feature and true if the
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// user has enabled the feature. Otherwise, if the feature is not enabled, a
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// zero-value and false are returned.
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func (f Feature[T]) Lookup() (v T, ok bool) {
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// https://github.com/open-telemetry/opentelemetry-specification/blob/62effed618589a0bec416a87e559c0a9d96289bb/specification/configuration/sdk-environment-variables.md#parsing-empty-value
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//
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// > The SDK MUST interpret an empty value of an environment variable the
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// > same way as when the variable is unset.
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vRaw := os.Getenv(f.key)
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if vRaw == "" {
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return v, ok
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}
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return f.parse(vRaw)
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}
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// Enabled returns if the feature is enabled.
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func (f Feature[T]) Enabled() bool {
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_, ok := f.Lookup()
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return ok
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}
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