1 files changed, 108 insertions, 0 deletions
diff --git a/vendor/go.opentelemetry.io/otel/sdk/trace/sampler_env.go b/vendor/go.opentelemetry.io/otel/sdk/trace/sampler_env.go
new file mode 100644
index 000000000..02053b318
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/sdk/trace/sampler_env.go
@@ -0,0 +1,108 @@
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package trace // import "go.opentelemetry.io/otel/sdk/trace"
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+const (
+	tracesSamplerKey    = "OTEL_TRACES_SAMPLER"
+	tracesSamplerArgKey = "OTEL_TRACES_SAMPLER_ARG"
+
+	samplerAlwaysOn                = "always_on"
+	samplerAlwaysOff               = "always_off"
+	samplerTraceIDRatio            = "traceidratio"
+	samplerParentBasedAlwaysOn     = "parentbased_always_on"
+	samplerParsedBasedAlwaysOff    = "parentbased_always_off"
+	samplerParentBasedTraceIDRatio = "parentbased_traceidratio"
+)
+
+type errUnsupportedSampler string
+
+func (e errUnsupportedSampler) Error() string {
+	return fmt.Sprintf("unsupported sampler: %s", string(e))
+}
+
+var (
+	errNegativeTraceIDRatio       = errors.New("invalid trace ID ratio: less than 0.0")
+	errGreaterThanOneTraceIDRatio = errors.New("invalid trace ID ratio: greater than 1.0")
+)
+
+type samplerArgParseError struct {
+	parseErr error
+}
+
+func (e samplerArgParseError) Error() string {
+	return fmt.Sprintf("parsing sampler argument: %s", e.parseErr.Error())
+}
+
+func (e samplerArgParseError) Unwrap() error {
+	return e.parseErr
+}
+
+func samplerFromEnv() (Sampler, error) {
+	sampler, ok := os.LookupEnv(tracesSamplerKey)
+	if !ok {
+		return nil, nil
+	}
+
+	sampler = strings.ToLower(strings.TrimSpace(sampler))
+	samplerArg, hasSamplerArg := os.LookupEnv(tracesSamplerArgKey)
+	samplerArg = strings.TrimSpace(samplerArg)
+
+	switch sampler {
+	case samplerAlwaysOn:
+		return AlwaysSample(), nil
+	case samplerAlwaysOff:
+		return NeverSample(), nil
+	case samplerTraceIDRatio:
+		if !hasSamplerArg {
+			return TraceIDRatioBased(1.0), nil
+		}
+		return parseTraceIDRatio(samplerArg)
+	case samplerParentBasedAlwaysOn:
+		return ParentBased(AlwaysSample()), nil
+	case samplerParsedBasedAlwaysOff:
+		return ParentBased(NeverSample()), nil
+	case samplerParentBasedTraceIDRatio:
+		if !hasSamplerArg {
+			return ParentBased(TraceIDRatioBased(1.0)), nil
+		}
+		ratio, err := parseTraceIDRatio(samplerArg)
+		return ParentBased(ratio), err
+	default:
+		return nil, errUnsupportedSampler(sampler)
+	}
+}
+
+func parseTraceIDRatio(arg string) (Sampler, error) {
+	v, err := strconv.ParseFloat(arg, 64)
+	if err != nil {
+		return TraceIDRatioBased(1.0), samplerArgParseError{err}
+	}
+	if v < 0.0 {
+		return TraceIDRatioBased(1.0), errNegativeTraceIDRatio
+	}
+	if v > 1.0 {
+		return TraceIDRatioBased(1.0), errGreaterThanOneTraceIDRatio
+	}
+
+	return TraceIDRatioBased(v), nil
+}