sampler_env.go

Documentation: go.opentelemetry.io/otel/sdk/trace

     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  }
   109
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