gitlab.com/gitlab-org/labkit@v1.21.0/tracing/env_extractor.go (about)

     1  package tracing
     2  
     3  import (
     4  	"context"
     5  	"os"
     6  	"strings"
     7  
     8  	opentracing "github.com/opentracing/opentracing-go"
     9  	"github.com/opentracing/opentracing-go/ext"
    10  	"gitlab.com/gitlab-org/labkit/correlation"
    11  )
    12  
    13  // ExtractFromEnv will extract a span from the environment after it has been passed in
    14  // from the parent process. Returns a new context, and a defer'able function, which
    15  // should be called on process termination.
    16  func ExtractFromEnv(ctx context.Context, opts ...ExtractFromEnvOption) (context.Context, func()) {
    17  	/* config not yet used */ applyExtractFromEnvOptions(opts)
    18  	tracer := opentracing.GlobalTracer()
    19  
    20  	// Extract the Correlation-ID
    21  	envMap := environAsMap(os.Environ())
    22  	correlationID := envMap[envCorrelationIDKey]
    23  	if correlationID != "" {
    24  		ctx = correlation.ContextWithCorrelation(ctx, correlationID)
    25  	}
    26  
    27  	// Attempt to deserialize tracing identifiers
    28  	wireContext, err := tracer.Extract(
    29  		opentracing.TextMap,
    30  		opentracing.TextMapCarrier(envMap))
    31  
    32  	if err != nil {
    33  		/* Clients could send bad data, in which case we simply ignore it */
    34  		return ctx, func() {}
    35  	}
    36  
    37  	// Create the span referring to the RPC client if available.
    38  	// If wireContext == nil, a root span will be created.
    39  	additionalStartSpanOpts := []opentracing.StartSpanOption{
    40  		ext.RPCServerOption(wireContext),
    41  	}
    42  
    43  	if correlationID != "" {
    44  		additionalStartSpanOpts = append(additionalStartSpanOpts, opentracing.Tag{Key: "correlation_id", Value: correlationID})
    45  	}
    46  
    47  	serverSpan := opentracing.StartSpan(
    48  		"execute",
    49  		additionalStartSpanOpts...,
    50  	)
    51  	ctx = opentracing.ContextWithSpan(ctx, serverSpan)
    52  
    53  	return ctx, func() { serverSpan.Finish() }
    54  }
    55  
    56  func environAsMap(env []string) map[string]string {
    57  	envMap := make(map[string]string, len(env))
    58  	for _, v := range env {
    59  		s := strings.SplitN(v, "=", 2)
    60  		envMap[s[0]] = s[1]
    61  	}
    62  	return envMap
    63  }