traefik/pkg/middlewares/observability/middleware.go

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2024-03-12 08:48:04 +00:00
package observability
2024-01-08 08:10:06 +00:00
import (
"context"
"net/http"
"github.com/containous/alice"
"github.com/rs/zerolog/log"
"github.com/traefik/traefik/v3/pkg/logs"
"github.com/traefik/traefik/v3/pkg/tracing"
"go.opentelemetry.io/otel/attribute"
"go.opentelemetry.io/otel/trace"
)
// Traceable embeds tracing information.
type Traceable interface {
GetTracingInformation() (name string, typeName string, spanKind trace.SpanKind)
}
// WrapMiddleware adds traceability to an alice.Constructor.
func WrapMiddleware(ctx context.Context, constructor alice.Constructor) alice.Constructor {
return func(next http.Handler) (http.Handler, error) {
if constructor == nil {
return nil, nil
}
handler, err := constructor(next)
if err != nil {
return nil, err
}
if traceableHandler, ok := handler.(Traceable); ok {
name, typeName, spanKind := traceableHandler.GetTracingInformation()
log.Ctx(ctx).Debug().Str(logs.MiddlewareName, name).Msg("Adding tracing to middleware")
return NewMiddleware(handler, name, typeName, spanKind), nil
}
return handler, nil
}
}
// NewMiddleware returns a http.Handler struct.
func NewMiddleware(next http.Handler, name string, typeName string, spanKind trace.SpanKind) http.Handler {
return &middlewareTracing{
next: next,
name: name,
typeName: typeName,
spanKind: spanKind,
}
}
// middlewareTracing is used to wrap http handler middleware.
type middlewareTracing struct {
next http.Handler
name string
typeName string
spanKind trace.SpanKind
}
func (w *middlewareTracing) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
if tracer := tracing.TracerFromContext(req.Context()); tracer != nil {
tracingCtx, span := tracer.Start(req.Context(), w.typeName, trace.WithSpanKind(w.spanKind))
defer span.End()
req = req.WithContext(tracingCtx)
span.SetAttributes(attribute.String("traefik.middleware.name", w.name))
}
if w.next != nil {
w.next.ServeHTTP(rw, req)
}
}