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package tracing
import (
"context"
"fmt"
"os"
"sort"
opentracing "github.com/opentracing/opentracing-go"
"gitlab.com/gitlab-org/labkit/correlation"
logkit "gitlab.com/gitlab-org/labkit/log"
)
// envCorrelationIDKey is used to pass the current correlation-id over to the child process.
const envCorrelationIDKey = "CORRELATION_ID"
// EnvInjector will inject tracing information into an environment in preparation for
// spawning a child process. This includes trace and span identifiers, as well
// as the GITLAB_TRACING configuration. Will gracefully degrade if tracing is
// not configured, or an active span is not currently available.
type EnvInjector func(ctx context.Context, env []string) []string
// NewEnvInjector will create a new environment injector.
func NewEnvInjector(opts ...EnvInjectorOption) EnvInjector {
/* config not yet used */ applyEnvInjectorOptions(opts)
return func(ctx context.Context, env []string) []string {
envMap := map[string]string{}
// Pass the Correlation-ID through the environment if set
correlationID := correlation.ExtractFromContext(ctx)
if correlationID != "" {
envMap[envCorrelationIDKey] = correlationID
}
// Also include the GITLAB_TRACING configuration so that
// the child process knows how to configure itself
v, ok := os.LookupEnv(tracingEnvKey)
if ok {
envMap[tracingEnvKey] = v
}
span := opentracing.SpanFromContext(ctx)
if span == nil {
// If no active span, short circuit
return appendMapToEnv(env, envMap)
}
carrier := opentracing.TextMapCarrier(envMap)
err := span.Tracer().Inject(span.Context(), opentracing.TextMap, carrier)
if err != nil {
logkit.ContextLogger(ctx).WithError(err).Error("tracing span injection failed")
}
return appendMapToEnv(env, envMap)
}
}
// appendMapToEnv takes a map of key,value pairs and appends it to an
// array of environment variable pairs in `K=V` string pairs.
func appendMapToEnv(env []string, envMap map[string]string) []string {
additionalItems := []string{}
for k, v := range envMap {
additionalItems = append(additionalItems, fmt.Sprintf("%s=%s", k, v))
}
sort.Strings(additionalItems)
return append(env, additionalItems...)
}
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