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sampler_env.go (3020B)

      1 // Copyright The OpenTelemetry Authors
      2 //
      3 // Licensed under the Apache License, Version 2.0 (the "License");
      4 // you may not use this file except in compliance with the License.
      5 // You may obtain a copy of the License at
      6 //
      7 //     http://www.apache.org/licenses/LICENSE-2.0
      8 //
      9 // Unless required by applicable law or agreed to in writing, software
     10 // distributed under the License is distributed on an "AS IS" BASIS,
     11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     12 // See the License for the specific language governing permissions and
     13 // limitations under the License.
     14 
     15 package trace // import "go.opentelemetry.io/otel/sdk/trace"
     16 
     17 import (
     18 	"errors"
     19 	"fmt"
     20 	"os"
     21 	"strconv"
     22 	"strings"
     23 )
     24 
     25 const (
     26 	tracesSamplerKey    = "OTEL_TRACES_SAMPLER"
     27 	tracesSamplerArgKey = "OTEL_TRACES_SAMPLER_ARG"
     28 
     29 	samplerAlwaysOn                = "always_on"
     30 	samplerAlwaysOff               = "always_off"
     31 	samplerTraceIDRatio            = "traceidratio"
     32 	samplerParentBasedAlwaysOn     = "parentbased_always_on"
     33 	samplerParsedBasedAlwaysOff    = "parentbased_always_off"
     34 	samplerParentBasedTraceIDRatio = "parentbased_traceidratio"
     35 )
     36 
     37 type errUnsupportedSampler string
     38 
     39 func (e errUnsupportedSampler) Error() string {
     40 	return fmt.Sprintf("unsupported sampler: %s", string(e))
     41 }
     42 
     43 var (
     44 	errNegativeTraceIDRatio       = errors.New("invalid trace ID ratio: less than 0.0")
     45 	errGreaterThanOneTraceIDRatio = errors.New("invalid trace ID ratio: greater than 1.0")
     46 )
     47 
     48 type samplerArgParseError struct {
     49 	parseErr error
     50 }
     51 
     52 func (e samplerArgParseError) Error() string {
     53 	return fmt.Sprintf("parsing sampler argument: %s", e.parseErr.Error())
     54 }
     55 
     56 func (e samplerArgParseError) Unwrap() error {
     57 	return e.parseErr
     58 }
     59 
     60 func samplerFromEnv() (Sampler, error) {
     61 	sampler, ok := os.LookupEnv(tracesSamplerKey)
     62 	if !ok {
     63 		return nil, nil
     64 	}
     65 
     66 	sampler = strings.ToLower(strings.TrimSpace(sampler))
     67 	samplerArg, hasSamplerArg := os.LookupEnv(tracesSamplerArgKey)
     68 	samplerArg = strings.TrimSpace(samplerArg)
     69 
     70 	switch sampler {
     71 	case samplerAlwaysOn:
     72 		return AlwaysSample(), nil
     73 	case samplerAlwaysOff:
     74 		return NeverSample(), nil
     75 	case samplerTraceIDRatio:
     76 		if !hasSamplerArg {
     77 			return TraceIDRatioBased(1.0), nil
     78 		}
     79 		return parseTraceIDRatio(samplerArg)
     80 	case samplerParentBasedAlwaysOn:
     81 		return ParentBased(AlwaysSample()), nil
     82 	case samplerParsedBasedAlwaysOff:
     83 		return ParentBased(NeverSample()), nil
     84 	case samplerParentBasedTraceIDRatio:
     85 		if !hasSamplerArg {
     86 			return ParentBased(TraceIDRatioBased(1.0)), nil
     87 		}
     88 		ratio, err := parseTraceIDRatio(samplerArg)
     89 		return ParentBased(ratio), err
     90 	default:
     91 		return nil, errUnsupportedSampler(sampler)
     92 	}
     93 }
     94 
     95 func parseTraceIDRatio(arg string) (Sampler, error) {
     96 	v, err := strconv.ParseFloat(arg, 64)
     97 	if err != nil {
     98 		return TraceIDRatioBased(1.0), samplerArgParseError{err}
     99 	}
    100 	if v < 0.0 {
    101 		return TraceIDRatioBased(1.0), errNegativeTraceIDRatio
    102 	}
    103 	if v > 1.0 {
    104 		return TraceIDRatioBased(1.0), errGreaterThanOneTraceIDRatio
    105 	}
    106 
    107 	return TraceIDRatioBased(v), nil
    108 }