env.go

// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0

package propagation // import "go.opentelemetry.io/otel/propagation"

import (
	"os"
	"strings"
)

// EnvCarrier is a TextMapCarrier that uses the environment variables as a
// storage medium for propagated key-value pairs. The keys are uppercased
// before being used to access the environment variables.
// This is useful for propagating values that are set in the environment
// and need to be accessed by different processes or services.
// The keys are uppercased to avoid case sensitivity issues across different
// operating systems and environments.
type EnvCarrier struct{}

var _ TextMapCarrier = EnvCarrier{}

// Get returns the value associated with the passed key.
// The key is uppercased before being used to access the environment variable.
func (EnvCarrier) Get(key string) string {
	k := strings.ToUpper(key)
	return os.Getenv(k)
}

// Set stores the key-value pair in the environment variable.
// The key is uppercased before being used to set the environment variable.
func (EnvCarrier) Set(key, value string) {
	k := strings.ToUpper(key)
	_ = os.Setenv(k, value)
}

// Keys lists the keys stored in this carrier.
// This method is not implemented for EnvCarrier as it is not possible to
// list all environment variables in a portable way.
func (EnvCarrier) Keys() []string {
	// I don't know why TextMapCarrier even has a Keys method.
	// It looks like it was some mistake in the original design.
	return nil
}